A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT

IMPROVING THE VALUE AND SUSTAINABILITY OF LAYING HEN MANURE MAY 2019 B r r e it rt is o h p F r p e u e S

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www.wotapullet.co.uk A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 03

Contents

Executive Summary 04

1 Introduction 08

1.1 Poultry manure: resource or waste? 09 1.2 Changing legislative requirements 10 1.3 Alternative uses of poultry manures 11 1.4 Aims of this report 12

2 Key legislation and impacts on land spreading 14

2.1 Nitrate vulnerable zones (NVZs) 15 2.2 Environmental permitting 19 2.3 Farming rules for water 21 2.4 Clean air strategy 22

3 Fertiliser values of poultry manure 23

3.1 Nutrient content of poultry manures 25 3.2 Poultry manure values 27 3.3 Maximizing fertiliser value - housing and management factors 28

4 Alternative uses of poultry manure 32

4.1 Incineration 34 4.2 Drying and pelleting 46 4.3 Composting 55 4.4 Anaerobic digestion 64

5 Conclusions 78

6 Photographs 86

Authors Jason Gittins Jon Walton

ADAS Unit 10D, Cefn Llan Science Park, Aberystwyth SY23 3AH EXECUTIVE SUMMARY A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 05

This report provides a practical guide for Added to this are the impacts of recent trends farmers who are currently spreading poultry in the free range sector. In certain parts of the manure onto their own land, exporting it to country, there are now large numbers of land operated by others or considering farms with free range egg production alternative uses for it. enterprises. Locally, this can mean a surplus of poultry manure relative to fertiliser The background is a changing legislative and requirements on neighbouring land and policy landscape which is likely to impact in therefore additional manure haulage costs. future upon both manure utilisation methods and new poultry housing systems. For producers who are currently The Farming Rules for Water (announced by land-spreading poultry manure, this report Defra in 2018) seek to tackle diffuse pollution has estimated the current value of key from agriculture and include new nutrients contained (nitrogen, phosphorus requirements on land spreading and and potassium). At 50% manure dry matter preventing pollution risk. The Clean Air content, the value is likely to be between £20 Strategy (launched by Defra early in 2019) and £26 per tonne according to application sets out new rules to minimise pollution from time and method. A key variable is the dry organic and inorganic fertiliser use. It matter content of the manure. Further introduces the issue of mandatory design calculations show that at 80% dry matter, the standards for new poultry housing. value rises to £41 per tonne. These prices relate to the value of the nutrients contained 06

in the manure and they therefore exclude the considered only by very large free range costs of haulage and land-spreading. producers (over 100,000 birds) or by local groups operating on a collaborative basis. In a review of alternative uses for poultry manure, the report considers manure 2 Drying and pelleting incineration, drying and pelleting, Drying laying hen manure increases its composting and anaerobic digestion. The nutrient value and makes it easier to outputs from these processes can be handle. The process can use air from the summarised as either i) a dry, solid product poultry house or waste heat from other which is easier to store, handle and spread sources such as anaerobic digestion or than ‘fresh’ poultry manure and therefore has incineration. Drying systems can be set up greater potential value or ii) a fuel which can next to the poultry house and the smallest be used to generate electricity or heat, available is considered suitable for 12,000 together with a residual product which also birds. Once dried, pelleting the manure has a saleable value. can then add further value through sale as a fertiliser for commercial or domestic use. The report provides a concise profile of each Pelleting systems are more expensive to process and the conclusions section includes install and run than drying systems and it a ‘side-by-side’ comparison in the form of a is considered that a minimum of around single table. A brief outline of each process is 64,000 birds would be needed to justify provided below. the costs.

1 Incineration 3 Composting Dry manures (over 55% dry matter) can be Poultry manure can be composted but it incinerated to provide on-farm heat or to needs to be combined with a carbon-rich generate electricity that can be used material to optimise the process. The either on-farm or exported to the grid. economic model for composting normally Payments may be received from relies on a gate fee being charged for government incentive schemes such as incoming raw materials such as ‘green the Feed in Tariff (FIT) and the Renewable waste’. This can provide a substantial part Heat Incentive (RHI). The residual ash also (or all) of the revenue received. Although has a saleable value. Capital costs are high the compost itself has useful fertiliser and therefore this method is likely to be value, the prices obtained for it are often A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 07

low. Low capital cost ‘windrow’ systems costs could encourage and hasten change in can be used for composting and this can the sector. For on-farm systems that produce be undertaken outdoors on a concrete heat (such as incineration and anaerobic base or within an existing building, if digestion), there are opportunities to use a available. However the process is likely to proportion of this to provide warmth to free be quicker and better controlled if more range houses at certain times of the year. This expensive ‘in-vessel’ systems are used. could provide added benefits including reduced ammonia and drier manure and litter. 4 Anaerobic digestion Anaerobic digestion takes organic If high capital costs continue to make materials (generally wastes) and in investment in alternative uses for manure anaerobic conditions, produces gas which ‘out-of-reach’ for smaller producers, there is used for energy generation. The may be increased interest in collaborative digestion process makes a more approaches. A model could be developed homogenous and stable product from the whereby a manure handling facility is original feedstock and this can be used as established at a central site, serving the a fertiliser. The high nitrogen content of needs of a number of local producers, who poultry manure generally limits its would all supply manure to it. inclusion within a feedstock mix to 20% although new technological Such an approach could also become developments aim to allow the use of up increasingly attractive if future controls mean to 100% poultry manure in future. In that farmers cannot continue indefinitely addition, laying hen manure contains with their current land spreading activities. calcium grit which is unsuitable for use in AD unless the system enables grit extraction.

The report finds that in general, capital costs of ‘alternative’ manure utilisation systems are high and that there is a lack of systems tailored to smaller producers. The Clean Air Strategy indicates that future support may be available to farmers (although the details are not yet available) and assistance with capital 1 INTRODUCTION A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 09

1.1 Poultry manure: resource or waste?

Poultry manure and used litter are inevitable emissions and potential fly infestations are by-products of free range egg production. avoided. They can be viewed either as a valuable resource – for use on farm or sold to third For producers with little or no additional land parties - or alternatively as a waste to be for spreading, suitable arrangements must disposed of. be made with recipient neighbouring farmers. In some areas with high poultry It is well-known that manure and used litter populations and limited available land this from poultry is a valuable source of the plant may be difficult and the potential saleable nutrients nitrogen, phosphorus, potassium value of the manure can be offset by high and sulphur. When spread to land, these transport costs. nutrients reduce the need for manufactured nutrients to be applied to meet optimum plant demand. Poultry manures also provide additional benefits, such as helping to improve soil structure.

However, manure application to land must be carefully managed in order to maximise fertiliser values, to minimise nutrient losses to the environment and to ensure that odour 10

1.2 Changing legislative requirements

In England, poultry manure spreading is Considered together, existing and planned closely controlled in nitrate vulnerable zones new legislation is likely to impose extra (NVZ). Poultry farmers who are outside NVZ control over poultry manure spreading to area but who operate with an environmental land. This may require additional and permit (exceeding 40,000 bird places) are therefore more distant land to be made subject to similar requirements. Further available, with consequential increases in controls were announced by Defra in the transport costs. With this in mind, some form of the Farming Rules for Water (April producers are now considering alternative 2018)1 and the ‘Clean Air Strategy’2 (January uses of poultry manure both to ‘future-proof’ 2019) which includes plans for further their businesses and to achieve additional legislation to reduce ammonia emissions. income from the laying hen manure produced.

1 www.gov.uk/government/publications/farming-rules-for-water-in-england 2 www.gov.uk/government/publications/clean-air-strategy-2019 A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 11

1.3 Alternative uses of poultry manures

Alternative uses of poultry manure and used To date, these systems have been adopted by litter have been under consideration for very few egg producers and the vast majority many years. However interest has recently still use traditional land–spreading for their increased, partly due to the likelihood of manures. By contrast, there has been more additional land spreading controls. Farmers uptake of alternatives to land-spreading in with larger flock sizes may face more difficulties the broiler sector, including the construction in finding local land for spreading. However of large power-generating plants in the east these may be best-placed to adopt alternative of England which use broiler litter as a raw manure uses, due to economies of scale. material. This probably reflects differences in the nature and analysis of manures from The main processes used to produce laying hens and litters from broilers and the alternative products from manures include different scale of the two sectors. incineration, drying, pelleting, composting and digesting.

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1.4 Aims of this report

This report provides a practical guide for In Section 3, we consider the fertiliser value farmers who are currently spreading poultry of poultry manures and the financial benefits manure onto their own land, exporting it to of applying these to land. The extent, land operated by others or considering practical implications and reasons for alternative uses. variability due to differences in manure dry matter and seasonal effects is set out. Current legislation and future developments are described in more detail in Section 2 to set out the ‘framework’ against which land- spreading will be undertaken in future. The focus here is on legislation in England as it relates to conventional (i.e. not organic) free range systems. Some differences may apply in other countries within the UK both at present and in future.

A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 13

In Section 4, we provide a concise review of Finally the conclusions are presented in alternative uses for poultry manures, using a Section 5 with a ‘side-by-side’ summary standard format and covering key comparison of the alternative uses requirements, commercial opportunities and considered. The Executive Summary (at the costs. start of the report) is a self-contained section which provides an overview of the whole report.

2 KEY LEGISLATION AND IMPACTS ON LAND SPREADING A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 15

This section considers relevant current legislation and the likely impacts of new requirements. It is clear that legislative controls are gradually tightening with regard to land-spreading of manures and this may encourage more egg producers to consider other options for manure processing and utilisation.

2.1 Nitrate vulnerable zones (NVZs)

These are areas that have been designated as 2.1.1 Use of organic manures being at risk of agricultural nitrate pollution. In NVZ areas, a maximum of 170kg They were first identified over 20 years ago per hectare of nitrogen can be but since then, the area included has applied via organic manures5 (e.g. expanded. NVZ areas currently account for from poultry) on a holding in each around 55% of all land in England. An online calendar year. This includes any tool is available, allowing farmers to manure that is directly deposited by determine whether a particular area of land outdoor livestock. On that basis, if is included within an NVZ area3. poultry manure is spread onto grassland grazed by cattle during the Within NVZ areas the maximum amount of year, account must be taken of the nitrogen that can be applied to land is manure directly deposited by the specified as a legal requirement. Specific cattle. rules are in place in relation to the application of organic manures. These relate This maximum amount (170kg per to the total amount applied, the timing of hectare) is the limit that applies as an spreading and any areas of land which average across the whole holding cannot be used for spreading. Full details can and separate to this is an annual field be found on the UK government website4 limit. The field limit is 250kg per but a practical summary of NVZ requirements hectare from organic manures is provided below. spread in NVZ areas. This excludes

3 https://environment-agency.cloud.esriuk.com/farmers/ 4 https://www.gov.uk/government/collections/nitrate-vulnerable-zones#nvz-designations-2017-to-2020 5 The term ‘organic manures’ generally refers to livestock manures and other organic wastes. It should not be taken to refer only to organic systems of livestock production 16

nitrogen from any manures In addition, NVZ rules state that no deposited by grazing animals. more than 8 tonnes of poultry manure per hectare (likely to be 2.1.2 Closed periods for spreading and equivalent to a total of around 150kg storage requirements of nitrogen at 40% dry matter) may Manure and litter from laying hens be applied in a single application cannot be spread in NVZ areas at from the end of the closed period certain times of the year. The length until the end of February. At least of the ‘closed period’ depends upon three weeks must be allowed the nature of the soil and whether between successive applications. the spreading is on grass land or tillage (cultivated) land. Table 1 below sets out the closed periods that apply.

Table 1. Summary of closed period in NVZ areas in England Grassland Tillage land Sandy or shallow soils6 1 September to 31 December 1 August to 31 December All other soils 15 October to 31 January 1 October to 31 January

6 Sandy soils are defined at https://www.gov.uk/guidance/using-nitrogen-fertilisers-in-nitrate-vulnerable-zones#where-you- cant-spread-manufactured-fertilisers-or-organic-manures A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 17

2.1.3 Soil incorporation manures to land is covered in a Code Poultry manure spread onto bare soil of Good Agricultural Practice and or stubble (unless sown with seed) also by ‘Farming rules for water’ (see must be worked into the soil as soon section 2.3 below. as practical and within 24 hours at the latest. Section 5.4 of the Code of Good Agricultural Practice7 states that land 2.1.4 Non-spreading conditions applications should be limited to no and locations more than 250kg of ‘total nitrogen’ Poultry manure must not be spread per hectare in any 12 month period on fields that are waterlogged, (paragraph 394). This is higher than flooded or covered in snow, nor on the holding limit within an NVZ area. land that has been frozen for more This figure excludes direct deposition than 12 of the previous 24 hours. It of manure from grazing animals must not be spread within 50 metres which is included within NVZ limit. of a spring, well or borehole or within 10 metres of surface water. The Code also sets out ‘good practice’ in relation to the timing of manure 2.1.5 Outside NVZ areas applications to land, restrictions on In areas of England which are outside areas for spreading and application an NVZ, the application of poultry techniques.

7 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/268691/ pb13558-cogap-131223.pdf 18

Failure to comply with the terms of the Code does not inevitably result in prosecution outside NVZ areas but it may be taken into account by the Environment Agency in England, when exercising their powers. A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 19

2.2. Environmental permitting

Larger free range egg production units which every four years, recording the hold an environmental permit (over 40,000 weight and nutrient content of bird places on a site) are subject to manures applied to each field. requirements on manure management Manures should be analysed at least planning. Precise requirements depend on once during the production cycle; whether the manure is spread onto the farm’s analyses to include total and own land or if it is exported to others. If the available nitrogen and total farm is also in an NVZ area, the records being phosphorus. Soils should be analysed kept for NVZ purposes should be sufficient to for total phosphorus at least every meet permitting requirements. five years.

2.2.1 Permitted farms - Additional requirements include on-site spreading incorporation of manures spread Application rates of poultry manures onto un-cropped land or bare soils must not exceed 250 kg per hectare within 24 hours. Restrictions are in in any 12 month period, which is place to avoid spreading during equivalent to the field limit set in adverse conditions (e.g. no NVZ areas. spreading onto waterlogged or frozen land) and on unsuitable land A manure management plan must be (e.g. steeply-sloping). implemented and reviewed at least 20

2.2.2 Permitted farms - the land becomes unavailable for off-site spreading spreading or movement restrictions Even when manure is exported to are in place. This could require other farms, the permit holder (i.e. additional on-farm manure storage the egg producer) is still expected to or the use of other land for spreading. take measures to minimise pollution risks. Records should be kept of the quantities of manure removed and the relevant dates, including the name and address of the recipient and details of the land area available. Where a contractor or other third party takes the manure, they must confirm that manure will be spread in accordance with the Defra Code of Good Agricultural Practice8. Also, they must confirm that spreading will be in accordance with a manure management plan for the receiving land. Finally, there should be contingency plans in place in case

8 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/268691/ pb13558-cogap-131223.pdf

A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 21

2.3 Farming rules for water

These were introduced by Defra in April • Manures must not be stored on land 20189 with the aim of tackling diffuse water or applied to land within 10 metres pollution from agriculture and setting a of inland fresh water or within 50 consistent baseline of good practice for metres of a spring, well or borehole. agriculture in England. The key requirements are as follows: • Manures must not be applied if the soil is waterlogged, flooded or snow- • The application of organic manures covered; if it has been frozen for to cultivated land must be planned in more than 12 hours in the previous advance to meet soil and crop 24 hours and if there is a risk of nutrient needs and not exceed these causing pollution. levels. • Reasonable precautions must be • Planning must take into account taken to prevent significant soil where there is a significant risk of erosion and runoff from the pollution and the results of testing application of organic manure or for phosphorus, potassium, from poaching by animals. magnesium, pH and nitrogen levels in the soil. Analyses must be undertaken at least every 5 years.

9 The Reduction and Prevention of Agricultural Diffuse Pollution (England) Regulations 2018 22

2.4 Clean air strategy

Defra’s ‘Clean Air Strategy’10 was launched in managed in a no-till system) to be January 2019, setting out the UK government’s incorporated rapidly (within 12 plans to reduce ammonia emissions from hours) with legislation to be farming. Whilst it focuses on tackling air introduced in the shortest possible pollution in England, the strategy notes the time frame; ‘shared goals’ of the UK as a whole and so similar developments may be anticipated in • Mandatory design standards for new Scotland, Wales and Northern Ireland. poultry housing. The standards will be designed in collaboration with In the sections that are relevant to manures industry experts and will include from the free range egg production sector, design features to improve animal Defra state that: health and welfare and minimise environmental pollution to air ‘We will regulate to reduce ammonia (including greenhouse gas emissions from farming. We will: emissions), water and land as far as practicable; 1. Introduce rules on specific emissions reducing practices including; 2. Regulate to minimise pollution from organic and inorganic fertiliser use, • A requirement for all solid manure seeking advice from an expert group on spread to bare land (other than that the optimal policy approach’.

10 https://www.gov.uk/government/publications/clean-air-strategy-2019

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No details of how and when these rules will A further action contained within the come into force have been given, but the strategy states that Defra will require and introduction of new rules for the design of support farmers to make investments in the new poultry houses could have important farm infrastructure and equipment that will implications. reduce emissions. At present, no further details are available on the possible scope The strategy also states: and extent of the support referred to.

• ‘We will consult on each policy as quickly as possible to provide farmers, farm suppliers and farm service providers with certainty on the investments needed’;

• ‘We will require and support farmers to make investments in the farm infrastructure and equipment that will reduce emissions’.

3 FERTILISER VALUES OF POULTRY MANURE A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 25

The value of manure and used litter from free range laying hens as a fertiliser is based mainly upon its nutrient content. However moisture content is also important because it determines the extent to which nutrients are concentrated or diluted. This has implications for transport costs, ease of handling and the likely occurrence of odour complaints and fly infestations.

In this section, we consider typical nutrient contents, the extent of variation and the value of poultry manure as a fertiliser.

3.1 Nutrient content of poultry manures

Typical nutrient contents of poultry manures Total nitrogen, phosphate, potash, sulphur at a range of different dry matter percentages and magnesium contents all increase (on a are shown in Table 2. The dry matter content ‘weight per tonne’ basis) as the manure dry of layer manure is variable but the trend matter rises. The data in Table 2 make no towards fewer single-tier systems and more distinction between single-tier and multi-tier multi-tiers with belt manure removal has led systems at a given dry matter content. to a greater proportion of layer manure with dry matter contents greater than 50% according to Defra data11.

Table 2. Typical nutrient content of poultry manure (fresh weight basis)*

Total Total Dry matter Total nitrogen Total potash Total sulphur phosphate magnesium (%) (kg N/t) (kg K2O/t) (kg SO3/t) (kg P2O5/t) (kg MgO/t)

20 9.4 8.0 8.5 3.0 2.7 40 19.0 12.0 15.0 5.6 4.3 60 28.0 17.0 21.0 8.2 5.9 80 37.0 21.0 27.0 11.0 7.5

* Data taken from the Nutrient management Guide (RB209), AHDB (2017) 11 Defra (2015). Analysing the characteristics of UK pig and poultry manures and slurries. Defra project report SCF0202.http://sciencesearch.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location =None&ProjectID=19376&FromSearch=Y&Publisher=1&SearchText=SCF0202&SortString= ProjectCode&SortOrder=Asc&Paging=10#Description 26

Differences in manure nitrogen production The results, set out in Table 3 predict that from single-tier and multi-tier systems have levels of nitrogen per hen are higher in multi- been assessed using the ENCASH software tier than in single-tier systems, due to higher tool12. This allows farmers to calculate the dry matter content and less nitrogen loss in nitrogen production in manure based on the form of ammonia. They also show that specific dietary inputs and systems for levels are higher when covered stores are housing and manure management. used as opposed to field heaps.

Table 3. ENCASH13 estimates of manure nitrogen production from single-tier and multi-tier ree range layer systems Manure nitrogen production Free range system Manure storage (kg nitrogen/1000 birds) Multi-tier Covered store 649 Multi-tier Field heap 583 Single-tier Covered store 592 Single-tier Field heap 537

12 www.planet4farmers.co.uk/Content.aspx?name=ENCASH 13 ENCASH estimates are based on a production cycle of 420 days (16 to 76 weeks), 325 eggs/bird and a protein content in feed of 16.5%. Estimates used a feed conversion value of 2.65kg of feed per kg egg mass for single-tier systems and 2.54kg of feed per kg egg mass for multi-tier, given expected differences in feed intake between systems A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 27

3.2 Poultry manure values

The MANNER-NPK software tool14 was used the extent of the delay between application to assess the value of nutrients supplied by and incorporation into the soil (Table 4). The laying hen manure applications at a dry values do not include any allowance for matter content of 50%. The total nutrient transport or spreading costs, both of which value ranged from £20 per tonne to £26 per could be around £4-5 per tonne. tonne, depending on application timing and

Table 4. MANNER-NPK estimates14 of the nutrient value of laying hen manure (50% dry matter) at land spreading in autumn or spring, and with either i) no rapid soil incorporation or ii) incorporation within 6 hours

Application Incorporation Nitrogen value P2O5 value K2O value Total nutrient time within 6 hours (£/t) (£/t) (£/t) value (£/t)

Autumn No 2 11 7 20

Autumn Yes 2 11 7 20

Spring No 5 11 7 23

Spring Yes 8 11 7 26

14 http://www.planet4farmers.co.uk/Manner.aspx 15 MANNER-NPK estimates are based on a total application to a sandy loam soil of layer manure at 12 tonnes per hectare, either incorporated by plough within 6 hours of application or left on the soil surface (i.e. not incorporated). Estimates were made for manure applied in central England (annual rainfall of 650 mm) on 1 September, growing an early sown winter cereal crop or on 1 March growing a spring sown cereal. Manure dry matter and nutrient contents were the average values of the most recent laying hen manure data (Defra, 2015). Nutrient price data was based on the AHBD GB fertiliser price data averaged over April 2018-March 2019; ammonium nitrate (34.5% N) at £263 per tonne; triple superphosphate (46% P2O5) at £325 per tonne; muriate of potash (60% K2O) at £273 per tonne 28

It is clear that most of the value of the Poultry manure applications are also a source manure is in the phosphate element (£11 per of organic matter which has been shown to tonne) and in potash (£7 per tonne), improve soil biological and physical especially with an autumn application. functioning. Organic matter additions also Application timing had the biggest impact improve soil structure which has the on manure nitrogen value, with nitrogen potential to improve water retention supplied by spring applications worth (especially on light soils), reduce the risk of between £3 and £6 per tonne more than soil erosion and make cultivations easier. autumn applications. Such benefits have not been quantified but would be considered additional to the values Rapid soil incorporation increased the value set out in Table 4. of spring applied manure by £3 per tonne reflecting the reduction in ammonia loss. Finally, a similar approach based on MANNER There was no impact of soil incorporation on NPK was used to estimate manure nutrient the value of autumn applied manure, as values at a range of different dry matter nitrogen saved by reducing ammonia contents, from 20% to 80%. The same emissions typically leads to increased nitrate assumptions were made as in Table 4 and the leaching losses. results are shown in Table 5 opposite.

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Table 5. MANNER-NPK estimates of the nutrient value of laying hen manure at a range of different dry matters (20-80%) Nitrogen value Total nutrient Dry matter (%) P O value (£/t) K O value (£/t) (£/t) 2 5 2 value (£/t) 20 5 6 4 15 40 8 9 7 24 60 11 12 10 33 80 14 15 12 41 30

3.3 Maximising fertiliser value - 3.3 housing and management factors

Compliance with the Defra Code of Good • Keeping manure as dry as possible means Agricultural Practice for reducing ammonia that a greater proportion of readily emissions16 helps to maximise the fertiliser available nitrogen is in the uric acid form. value of manures. Key points to note are as This means that nitrogen is less likely to be follows: lost via ammonia volatilisation. During manure storage, there are benefits to covering manure, whether in purpose- built stores, in field heaps and on trailers. From a practical and commercial perspective, drier manure also means lower transport costs.

• Apply manure in the spring if possible to avoid nitrogen loss in winter due to leaching. Rapidly incorporating manure to minimise ammonia emissions is beneficial. The majority of ammonia emissions occur within 24 hours of application, hence it is best to incorporate as soon as practically possible, ideally within 6 hours of application.

16 www.gov.uk/government/publications/code-of-good-agricultural-practice-for-reducing-ammonia-emissions A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 31

• Use soil analysis to target manure applications to soils which have a requirement for phosphate and potash. Laying hen manure applications typically supply more phosphate and potash than crops use in one harvest. Regular, repeat applications to the same land over several years has the potential to increase soil phosphorus concentrations in particular to levels which may increase the risk of leaching to local watercourses.

• Use AHDB’s Nutrient Management Guide RB20917 to assess crop nutrient requirement and RB209 or MANNER-NPK18 to quantify crop available nutrient supply from manure applications.

17 https://ahdb.org.uk/knowledge-library/rb209-section-1-principles-of-nutrient-management-and-fertiliser-use 18 http://www.planet4farmers.co.uk/ 4 ALTERNATIVE USES OF POULTRY MANURE A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 33

In this section, we provide a concise review For each process, a technical description is of alternative uses for poultry manures for provided together with an assessment of key those interested in exploring options other requirements and commercial opportunities than land spreading. The output from the for free range producers. Typical costs and processes considered (combustion, drying, returns and potential difficulties are set out, pelleting, composting and digestion) can be together with possible future innovations summarised either as: and developments.

• A dry, solid product which is easier to Farm-specific issues such as the location and store, handle and spread than ‘fresh’ scale of free range enterprise are also poultry manure and has greater potential important in determining the likely feasibility value, or of each process. This document is therefore intended to be used as a basis for farmers to • A fuel which can be used to generate begin more detailed discussions based on electricity or heat, together with a residual their own circumstances. product from the manure which also has a saleable value. Cost indications are based on prevailing prices in early 2019.

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4.1 Incineration

Dry manures (over 55% dry matter) can be viable in a farm situation. incinerated to provide on-farm heat or to generate electricity that can be used either However poultry manure is an animal on-farm or exported to the grid. Payments by-product and since 2014, may be received from government incentive legislation has allowed the energy to schemes such as the Feed in Tariff (FIT) and be recovered from animal by-product the Renewable Heat Incentive (RHI). The incineration20. Compliance with residual ash also has a saleable value. regulatory requirements is therefore less onerous in terms of monitoring Capital costs are high and therefore this and reporting and this has made method is likely to be considered only by manure incineration a feasible option very large free range producers or by local for some farmers. groups operating on a collaborative basis. The process involves burning manure 4.1.1 Technical description in a combustion unit and recovering In the past, incineration of poultry the heat which can then be used on manures and used litters was the farm to heat the poultry houses considered a waste activity under the or other on-site facilities through Waste Incineration Directive19. As a hot-water systems. Alternatively, it result, it was generally not can be converted to electricity in considered feasible or financially combined heat and power systems

19 Directive 2000/76/EC 20 Regulations (EU) 592/2014 and (EU) 2017/1262 A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 35

(CHP) so that the electricity is either the higher the energy production. used on-farm or can be exported for off-site sale. Incineration also creates The floor of the furnace has a sand a residue (ash) which represents bed through which air is released by between 8 and 15% of the weight of nozzles. An oil or gas burner is used the incoming manure. This has a to create initial heat at start-up and saleable value as a fertiliser. also for use during the process if required. Manure is fed into the top The process that has been shown to of the furnace from a storage bunker. be most suitable for poultry manure The fluidised beds operate by is based on ‘fluidised bed suspending manure particles on technology’. This is a proven upward-blowing jets of air during the technique used in other power- combustion process. The result is a generating plants for reliably using turbulent mixing of gas and solids, relatively inconsistent granular similar to a bubbling fluid, providing materials as a fuel. It is also well- efficient chemical processes and heat suited to ‘farm scale’ approaches as it transfer. can operate with variable moisture contents in manures although the Incineration temperatures must be recommended dry matter content is monitored to ensure that they are at least 55%. The drier the material, sufficient to meet the requirements 36

of animal by-products legislation but pressurised hot water temperatures they can be controlled to avoid the as low as 150°C. The process is higher temperatures that can create generally considered to be relatively more gaseous nitrogen oxides which inefficient (in terms of the may require abatement activity. percentage of energy conversion to power) but it still produces heat that The flue gas from the process has a is available for use. ORC uses a closed temperature of around 850°C and system and an organic chemical heat is recovered in a boiler section thermal fluid which has a lower as hot water or steam, depending on boiling point than water. the system for use elsewhere on site (to reduce heating costs) or to supply The ash resulting from the heat to the poultry houses as incineration process is collected in required. approximately equal quantities from the bed itself and also as ‘fly ash’ at Converting the heat to electrical the end of the process. The nutrient power is also possible in CHP analyses for the two are slightly systems. Power generation can be by different but both can be sold as a a steam engine or alternatively by high pH (alkaline) fertiliser high in Organic Rankine Cycle (ORC) phosphorus, potassium and trace technology that works with elements. A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 37

4.1.2 Commercial opportunities on farm location and distribution At present, BHSL Hydro21 is network. For on-farm use, the understood to supply the only opportunity could be taken to use a fluidised bed system for poultry proportion of the heat to warm the farmers who are considering manure poultry houses at certain times of incineration. A number of year and / or to dry the manure installations are already in operation within them. This could provide in the UK, although mainly for use in additional ‘poultry house-related’ the broiler sector at present. This environmental benefits. It could also equipment is able to meet emissions improve the performance of free requirements and it has the remote range flocks by lower feed use, lower monitoring infrastructure that can in-house ammonia levels and demonstrate compliance. Several improved litter quality. different models are available, including CHP systems and these Farmers generating electricity and vary in terms of scale and features. heat from such a system also gain income through government The electricity and / or heat schemes. Details are outlined below produced can be used on the farm and also within the separate case and electricity sales to the national study. grid may also be possible, depending

21 www.bhslhydro.com 38

• Feed in Tariff (FIT) payments for The residual ash can be bagged and the electricity generated. sold and expected analyses of key Different payment rates apply nutrients and selected trace depending on whether the elements are set out in Table 6. electricity is used on-site (lower rate) or exported into the grid Ease of handling and the high (higher rate). content of nutrients such as phosphorus and potassium mean • Renewable Heat Incentive (RHI) that higher sale prices should be payments for the heat produced. achieved for these materials than for Non-domestic rates are set ‘standard’ poultry manure. periodically and vary according to Alternatively, supply to a major the technology used. producer of branded fertiliser products such as Fibrophos22 is a Established sites can also benefit possibility, given that they already through the Renewables Obligations have market outlets and product Certificates (ROCs) support certifications already in place. mechanism but this is now closed to new installations.

22 www.fibrophos.co.uk A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 39

Table 6. Expected analysis of key nutrients and selected trace elements in ash from incineration

Bed Ash Fly Ash

Calcium (%) 64 47

Phosphorus (%) 10 16

Potassium (%) 10 15

Zinc (mg/kg) 860 1,380

Manganese (mg/kg) 920 1,640

4.1.3 Key considerations megawatts. It also specifies that the Requirements for facilities that manure itself must be ‘unprocessed’. incinerate poultry manure as a fuel are set out in EU legislation23. This The incineration process is regulated limits the scale of operations to a by the APHA and it must meet key maximum of one tonne of material requirements for time and per day – approximately a total rated temperature in the furnace and flue thermal input not exceeding five gas (2 seconds at over 850oC or 0.2 23 Commission Regulation 592/2014 40

seconds at over 1100oC.). therefore a concern to local residents.

An environmental permit must be in 4.1.4 Costs and returns place for the process and this is Whilst legislative change has made regulated by the local authority as a manure incineration an option at Part A(2)24 activity. Under permit farm level, the capital costs are still requirements, operators must have in high. This is likely to be a feasible place permanent procedures option only for the largest free range following the principles of HACCP to egg producers or as the basis for a identify, measure and control critical collaborative approach involving control points. An end-of-waste several smaller producers in the same protocol must be in place for the ash area. produced, with records kept to confirm the disposal method. A CHP system, together with an in- feed system for the manure, an ORC Planning permission is required prior generator, storage facilities for to starting. In some cases and for manure, fuel and ash and a heat certain locations this could be a distribution system (pumps and lengthy process and difficult to pipework) together with suitable obtain, particularly since incineration building is likely to cost in the region can be an emotive term and of £2 million. For a non-CHP system,

24 This category includes a range of different activities, including animal waste incineration A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 41

the cost may be reduced by around per year and an electricity value of 12 one-third (to approximately £1.3 pence per unit, likely annual returns million) but the potential income are around £600 per 1,000 birds. This would also be reduced. is equivalent to just under £20,000 per year for each 32,000 bird house. Initial planning costs are likely to be very variable but they could be in the The value of the ash as a fertiliser region of £40,000. Other costs to be should also be considered. Based on considered include labour, insurance, an estimated sale price for ash of £40 maintenance and fuel for start-up. per tonne and this representing 15% Some sources have estimated that by weight of the manure total (i.e. 4.8 these could total over £50,000 per tonnes per 1,000 birds), the value is year although for existing businesses, around £6,000 per 32,000 birds on some of the labour input would in an annual basis effect be transferred from previous manure-related activities such as land-spreading.

Based on the expected power conversion efficiency of the process, 32 tonnes of manure per 1,000 birds CASE STUDY ON POULTRY MANURE INCINERATION – JAMES BAXTER A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 43

James Baxter has 128,000 free range laying developing countries. A number of other hens on his farm near Stranraer in Scotland. machines and technologies were considered He uses an FBC750 Combined Heat and but these were discounted for reasons Power (CHP) system from BHSL to incinerate including lack of track record of burning the poultry manure produced, using the laying hen manure, the need to pellet the energy generated for heating and electricity. manure prior to incineration, potentially high Because of the farm location, James does not maintenance costs and concerns over high supply energy to the national grid and so it is emission levels. all used on farm. With a fluidised bed incineration system now James’s decision to opt for manure in place, James currently burns around 11-12 incineration came after a review of a number tonnes of manure each day from his 128,000 of different options as alternatives to land- hens and sees manure burning as part of an spreading. He considered anaerobic integrated approach with heat being digestion but identified a number of practical supplied back to the poultry houses to difficulties, concluding that other materials improve the environment and dry the were better-suited to the digestion process manure in-house on the belts. The electricity than the manure from his laying hens. He generated is used on the farm to reduce also considered other CHP machines, utility costs. Residual ash from the process is including small scale ‘plug and play’ units, used as a fertiliser on farm or sold to other which are often used for power generation in farmers but it is expected that it will soon be 44

sold to fertiliser companies to help them meet that basis accepts that larger bird numbers their environmental requirements for the use are needed to justify the investment at of recycled materials in their products. present. However the development of smaller (and therefore cheaper) machines in James has sought to benefit from future will happen in future if demand is government incentive schemes such as RHI which may create opportunities for others. and ROCS but he has found the accreditation Alternatively, installing a unit on a separate process to be complex and that expected industrial or other site with an on-site payments were severely delayed. This could demand for heat and electricity could be an have important negative implications for alternative model for the future. This could cash flow for businesses reliant on such then have manure supplied to it by a number payments. Key compliance issues for of local producers. payments included the need for incoming manure not to have been further-processed James estimates that his annual income from prior to incineration and there must also be a the activity is currently around £270,000 per clear and demonstrable use for the heat and year, based on RHI payments, electricity electricity generated. generated (net of the amount used in the process itself) and sales of ash as fertiliser. Overall, James considers that £2 million Having carefully worked out the costs and would be a reasonable budget figure for returns, James expects that the equipment capital costs for such a development and on costs will be re-paid within around seven A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 45

years. This does not take account of any benefits from improved flock performance which have been observed. These arise from improved environmental conditions, better flock health and higher in-house temperatures in winter, leading to reduced feed use. 46

4.2 Drying and pelleting

Drying laying hen manure increases its multi-tier than single-tier housing nutrient value and makes it easier to handle. since it can be linked to existing The process can use air from the poultry manure belts and conveyors. The house or waste heat from other sources such drying belts are ideally situated near as anaerobic digesters or incinerators. Drying to a poultry house so that they can systems can be set up next to the poultry utilise the extracted air from the house and the smallest available is ventilation system. considered suitable for 12,000 birds. Once dried, pelleting the manure can add further Daily manure removal from the house value through sale as a fertiliser for allows drying to be undertaken as a commercial or domestic use. Pelleting batch process, starting at the top level systems are more expensive to install and run of belts. A spreading mechanism is than drying systems and it is considered that used to distribute the manure evenly. a minimum of around 64,000 birds would be Perforations in the belts allow warm needed to justify the costs. air to circulate, so accelerating the drying process. 4.2.1 Technical description - drying Manure is typically dried by directing The manure is carried to the end of warm air over a series of manure the top level and it then drops down belts which are arranged on different to the belt below. This moves in the levels. The process is more suited to opposite direction, continuing the A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 47

drying process until the dried building that is distant to the manure finally reaches the bottom poultry houses. level, when it should achieve the required dry matter content. The Typically the drying process takes 48 process is usually fully-automated, hours to reach a dry matter content operating without direct supervision. of between 80 and 90%. However, At the end, dried manure is removed the duration depends factors such as from the system using an auger or the dry matter of the manure at the screw conveyor. start and the humidity, temperature and volume of the air used for Using warm air from the poultry drying. Pre-drying the manure in the house ventilation system provides a poultry house (i.e. before it enters the very cost-effective approach, utilising drying system) accelerates the drying heat generated by the hens which process. For this, the manure can be would otherwise be lost to the left on the manure belts in the house atmosphere. Warm air could also be for approximately 48 hours. generated using an external heat Alternatively, perforated plastic air source, such as from anaerobic tubes can be installed over the digestion or an incinerator CHP plant. manure belts in the house. These use This approach could enable the warm air from external fans to pass drying system to be set up in a over the manure. 48

The drying process reduces the process, a temperature of at least weight of the manure due to the loss 70oC must be maintained for at least of moisture. For example if one tonne one hour to kill harmful bacteria and of manure with an initial dry matter pathogens. The pellets are then content of 30% is dried to a dry cooled before they are stored in bulk matter content of 85%, the final or packed in bags and then weight is likely to be only around distributed. As a guide, the entire one-third of its initial weight. drying and pelleting process is likely to take around three days. 4.2.2 Technical description - pelleting To improve marketing opportunities, 4.2.3 Commercial opportunities the dried manure can be pelleted in a Whilst there are few poultry manure separate pelleting plant. For this, the drying systems in the UK at present, manure must have a dry matter the technology is well established content of between 80 and 85%. and commonly-used in countries such as the Netherlands, due to Typically, a pelleting plant includes a additional legislative requirements crusher which ensures that the dried for poultry manure in some locations. manure is broken down into smaller, uniform size particles before it enters A number of companies supply the pellet press. After the pelleting equipment for drying or pelleting A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 49

including Big Dutchman, Dorset weight reductions, the volume Group, Facco, Jansen Poultry of dried manure may be reduced Equipment, Stronga and VDL Agrotech. by 10 - 15%. Pelleting can reduce the volume by a further 50%, The main markets for dried and leading to further reductions in pelleted poultry manures are as transport costs. commercial fertilisers for agricultural and horticultural use and land • Higher nutrient values; since restoration and as garden fertilisers these increase (on a ‘kg per tonne’ for the domestic market. If required, basis) with higher dry matter poultry manure can be blended with content. other materials to produce a dried or pelleted fertiliser with a specific nutrient • Reduced ammonia emissions; profile. It could be used as a fuel for regular removal of manure from incineration in CHP and other plants. the poultry house and rapid drying of the manure reduces As a fertiliser, the main advantages of ammonia emissions. dried and pelleted manure are: • Higher nitrogen content; as less • Reduced storage and transport nitrogen is lost through ammonia costs; in addition to reported emissions, dried manure has 50

higher nitrogen content than is mainly based on the number of fresh manure. hens in the house. Typically one square metre of drying belt area is • Reduced odour and fly problems required for between 300 and 420 compared to fresh manure, with hens, depending on the local climate pelleted product representing a (temperature and humidity) and further improvement over ‘dried’. whether plastic or perforated steel belt systems are used. On this basis, a In addition, pelleted manure in 32,000 bird house would require particular is a more uniform product, around 80m2 of drying surface. As an easier to spread and apply to land. example, this could be provided by This makes it suitable for bagging in five drying layers, each one being small unit sizes, for sale to the 8m x 2m. The minimum house size general public through retail outlets. for drying systems is typically However this is likely to be a considered by suppliers to be around competitive sector requiring 12,000 birds. considerable marketing effort. The humidity and the temperature of 4.2.4 Key considerations the poultry house also affects the When air from the poultry house is drying process when ventilated air is used for drying, the size of the dryer used. The lower the air humidity and A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 51

the higher the temperature, the more to remove the manure regularly efficient the drying process. An during the flock cycle. internal house temperature of between 15 and 20oC is normally Drying systems can be retro-fitted to sufficient for drying but in free range an existing poultry house with drying systems this could be challenging in taking place either along the length many parts of the country, especially of the house or at the gable end, during winter. A higher volume of air depending on the location of air may therefore need to be directed outlets. Ideally the system should be over the manure. Alternatively, the set up so that it can dry manure from length of the drying process could be more than one house but in free extended (e.g. from two to three range situations, this may be difficult. days) or the manure may be Site design, the need to maintain pre-dried within the house. vehicular access (to collect the dried manure) and to maintain bird access Manure from single tier houses may to popholes and the range are other need additional treatment if it has practical issues that may arise. comparatively high moisture content. One option is to install a Pelleting systems come in a range of separate belt system under the capacity sizes from 400 kg per hour mini-pit slats in a single-tier system, (small) to 5 tonnes per hour (large). 52

Poultry sector suppliers suggest that legislation25 and must be approved a minimum of around 64,000 birds is by APHA. This stipulates temperature required to operate a small pelleting requirements (see section 4.2.2) system economically, unless the although alternative treatment manure is blended with another methods can be used if they have input material, in which case less been validated by APHA. manure is required. 4.2.5 Costs and returns On farms with an environmental The capital cost for drying systems permit (over 40,000 hen places), depends on factors such as the enforcement of any issues in relation desired dry matter content of the to manure drying is the responsibility final product, the amount of drying of the Environment Agency. If surface required, the heat source ammonia, odour or noise from the used to warm the air and whether plant was considered to be a pre-drying or air cleaning is required. problem then some form of mitigation may be required. Larger capacity drying systems are usually cheaper on a ‘per bird’ basis In order to sell pelleted poultry and if one system can dry the manure as a fertiliser, the plant must manure from multiple houses. On meet EU animal by-products that basis, one supplier estimates a

25 Regulation (EU) 1069/2009 and Regulation (EC) 142/2011 A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 53

cost of £2.50 per bird for a system plant capable of processing 750 kg capable of drying manure from per hour of manure (suitable for 32,000 birds. For 64,000 birds it would 200,000 laying hens) were recently be £1.70 per bird and for 128,000 estimated to be between £1.30 and birds it would be £1.30 per bird. £1.55 per bird. On this basis, the cost of drying and pelleting equipment Where feasible, retro fitting typically for a farm with 64,000 hens is likely to increases the cost of a drying system be in the order of £4 per bird. by around 20% compared to a new- build. In some cases, a pre-drying The energy consumption for system may need to be installed so pelleting is much higher than it is adding further cost. for drying. Suppliers indicate that a 750 kg per hour plant uses around 80 Operational costs vary, but they are kilowatt hours of electricity and that usually low given the use of the cost of producing one tonne of extracted air from poultry houses or pellets from dried manure is likely to waste heat from another activity. be between £20 and £35. Some electricity is required to operate the drying belts. Dry manure can command a higher price as a fertiliser as it has a higher Capital costs for a complete pelleting nutrient value than wet manure. For 54

example, Table 5 indicates a nutrient value of £41 per tonne at 80% dry matter. It also weighs less, so reducing transport costs and making storage easier.

For pelleted product, additional income needs to be obtained in order to offset the higher production costs. In the Netherlands, pelleted poultry manure is said to have market values ranging from between €60 and €250 per tonne, depending on its nutrient content and the target market. In the UK, 20kg bags of pelleted manure retail for around £16 however the producer/supplier may receive only a relatively modest proportion of this. A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 55

4.3 Composting

Poultry manure can be composted but it composting is widely practised in the needs to be combined with a carbon-rich UK as a recovery process for a range material to optimise the process. The of different organic materials and economic model for composting normally these can include poultry manures. relies on a gate fee being charged for The objective is to produce a high incoming raw materials such as ‘green waste’. quality fertiliser in an easier-to- This can provide a substantial part (or all) of handle form and to reduce the the revenue received. Although the compost volume and weight of the material itself has useful fertiliser value, the prices for final transport. obtained for it are often low. Compost has a high organic nitrogen Low capital cost ‘windrow’ systems can be content which should exceed the used for composting and this can be 70% threshold that enables it to be undertaken outdoors on a concrete base or spread during closed seasons in NVZ within an existing building, if available. areas (see also section 2). An However the process is likely to be quicker additional benefit of the composting and better controlled if more expensive process is an improvement in ‘in-vessel’ systems are used. microbiological quality e.g. by reducing pathogen load. 4.3.1 Technical description As a result of increased landfill costs, The process involves the conversion 56

of the material to compost in aerobic Lower dry matter content (i.e. conditions i.e. with sufficient air wetter material) can restrict the (oxygen) supply. It is a natural air supply and the composting process resulting from microbial mass becomes air-depleted activity which creates heat, with (anaerobic). This stops temperatures typically over 70oC composting activity, particularly within the material itself. To maintain in the initial stages and the the supply of oxygen which is process can become odorous. The essential to the process, physical dry matter content at the end of movement of the material is required the composting process is likely (turning) unless forced aeration to be around 60-70%. systems are in place. • The ratio of carbon to nitrogen In order to optimise the composting in the material to be composted. process the following two key The optimum ratio is around 20:1 variables need to be controlled: but as poultry manure is comparatively high in nitrogen • Moisture content. The target and low in carbon, it has a C:N should be a starting dry matter ratio of only around 10:1. Because content of between 40 and 60% of this, composting poultry in the material being composted. manure alone - whilst technically A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 57

possible - would not be of the process than at the end. recommended. Ideally, it should This could be done using general be mixed with a carbon-rich farm equipment although specialist material such as straw, wood or compost-turning machinery is general green waste. also available.

Whilst the principles of all composting More sophisticated options involve systems are similar, the methods purpose-built, ‘in-vessel’ systems and used range from the simple to the these can either be vertically or much more sophisticated. As a guide, horizontally arranged, the latter the composting process typically being available in modular form so takes between 8 and 12 weeks. that it can be extended according to capacity requirements. In these Open-air or covered windrow systems, the aeration necessary for systems in which the material forms the composting process to proceed an extended pyramid shape normally can be undertaken automatically e.g. 1-2 metres high on a concrete base using systems with aerated floors so provide the simplest and cheapest that oxygen levels can be controlled. approach. Ideally the material should Typically, the material is held ‘in be turned on approximately a weekly vessel’ for only around two weeks basis and more frequently at the start with the remainder of the time then 58

being spent in windrow or similar but at present, the economic model systems. for nearly all composting systems is based on the receipt of a gate fee for Within the poultry sector, Big incoming material. The compost Dutchman26 are one equipment itself may be supplied to the company with good experience of customer or end user either at a low in-vessel systems, mainly based on price or even free of charge. As well developments undertaken elsewhere as providing the main (or only) in Europe. source of income, the gate fee material brought in has the added 4.3.2 Commercial opportunities advantage of assisting the Compost is likely to be more valuable composting process by adjusting the as a fertiliser than raw poultry carbon to nitrogen ratio. manure since the dry matter is higher and odours are lower. These benefits A number of different materials could alone however are unlikely to offset be brought in for mixing with poultry the additional costs of the manure. Commonly-available composting process at present. materials include commercial green Process costs can be minimised by wastes from local authority using windrow systems in existing collections, recycling centres, buildings or on hardstanding areas vegetable processors and other

26 www.bigdutchman.de A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 59

farmers. These are likely to attract likely to be limited. The mushroom relatively modest gate fees. growing process is technically Alternatively, more specialised challenging and expensive to wastes such as gypsum can be used establish so it is unlikely to be and these normally attract higher something for poultry producers to gate fees although additional consider for themselves. requirements are likely to apply (see below). Locality is likely to have an A suitable compost material for important bearing on the availability mushroom growing could be based of such materials and on marketing on a mix of pre-wetted straw opportunities for the final product. (typically from barley) and poultry manure possibly with some added Fresh or part-composted poultry gypsum. After composting is manure could be provided to complete, mushroom growers mushroom growers in certain inoculate it with the appropriate locations so that they can produce a fungus to begin the growing process. compost material suitable for mushroom production. However, GB 4.3.3 Key considerations mushroom production has been in For a windrow approach, at least one decline as imports have increased square metre of floor area is required and so any such opportunities are per tonne of manure or other raw 60

materials treated. Space allowance Incoming raw materials may need to should be made for a three month be treated prior to composting e.g. composting process and then for a shredding of green waste, sorting to further three months storage exclude foreign bodies and any capacity. As a guide, a 64,000 bird materials that cannot be composted free range unit producing 40 tonnes and so additional space may be needed. of manure per 1,000 hens per year is likely to require a similar tonnage of An on-farm composting approach, another raw material to achieve the based on the use of existing correct C:N ratio. Thus the total buildings would not in principle weight would be equivalent to 80 require planning permission tonnes per 1,000 hens at the outset. although normal planning rules On this basis, at least 2,560m² of floor would apply if new buildings were to area would be required for six be constructed. An environmental months capacity. For open-air permit would be required if raw systems, dirty water storage facilities materials are being brought in for would be essential so that run-off composting. The precise could be contained. This would also requirements would largely depend be advisable for composting upon the nature of these raw undertaken within buildings, thus materials. For example, a process enabling thorough clean-out. whereby green waste from local A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 61

recycling centres is mixed with The use of in-vessel approaches can poultry manure is likely to require a alleviate odour problems at least in standard permit. A bespoke permit part but these considerably increase would be required if what are capital costs. considered ‘higher risk’ and more specialist wastes are brought in for Compliance with Publicly Available mixing with poultry manure. Permits Standard 100 (PAS100)27 is are issued by the Environment Agency considered essential for those and they would need to cover waste considering a composting process. management acceptance (i.e. control It is a recognised standard that of incoming materials), the process provides a guarantee of the product itself and the final use of the and its method of manufacture. composted material, whether for Importantly, it means that no further land spreading or other uses. waste regulatory controls are required, so that recipients and end Odours are a potential problem of users of the compost do not require the composting process. The likely their own environmental permit. To extent of problems depends upon achieve PAS100, suitable the materials used, the pH and the environmental management and moisture content of the manures, as HACCP system must be in place and well as the proximity of neighbours. costs and registrations apply.

27 http://www.qualitycompost.org.uk/standards/pas100 62

4.3.4 Costs and returns regulatory and process control. The commercial viability of composting is likely to be driven by The capital cost of an outdoor the gate fees that can be achieved for composting system situated on a incoming raw materials, with new concrete base is likely to be revenue from sales of the final around £40 per square metre, based product expected to be modest on site work, the cost of the concrete (probably less than £5 per tonne) in and related infrastructure. If an area most cases. There may however be of 2,560m² of concrete is required for regional differences, with perhaps 64,000 birds, the likely cost would greater demand in arable growing therefore be just over £100,000. areas than elsewhere. In vessel systems are much more Locality can play an important role in expensive and likely to start at determining gate fees but as a guide around £150 per tonne of material to a fee of around £20-30 per tonne be composted annually. For a system may be received for locally-sourced, composting 40 tonnes of manure easy-to-process green wastes. This with 40 tonnes of other raw material can rise to around £80-100 per tonne (i.e. 80 tonnes per week), the annual for wastes that are more difficult to throughput would be around 4,160 treat and which require more tonnes. At £150 per tonne, the A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 63

equipment cost would be in the order of £625,000. After adding buildings and other infrastructure, the total is likely to be in the region of £1 million. 64

4.4 Anaerobic digestion

Anaerobic digestion (AD) is a process which digest non-cellulosic substances in takes organic materials (generally wastes) organic matter feedstock and and in anaerobic conditions, produces gas produce energy. The raw materials which is used for energy generation. The used (i.e. the feedstock) are usually digestion process makes a more waste organic materials such as food homogenous and stable product from the or animal manure, but they could original feedstock and this can be used as a also be a purpose-grown crop. fertiliser. The high nitrogen content of poultry manure generally limits its inclusion The process produces a gaseous mix within a feedstock mix to 20% although (‘biogas’) which can be used to technological developments have allowed generate heat or electrical energy. the use of up to 100% poultry manure in This can either be used on-farm or it large scale plants. In addition, laying hen can be exported offsite e.g. by using manure contains calcium grit which is an engine-driven generator connected unsuitable for use in AD unless the system to the grid. The AD process also enables grit extraction. produces digestate which can be used as a nutrient rich fertiliser. 4.4.1 Technical description Anaerobic digestion (AD) is a process AD tank designs are arranged either which uses a culture of microbes in vertically or horizontally. Vertical tanks an air-excluded environment to take feedstock through a pipe at the A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 65

top of the tank on one side and the The AD process is similar in both digestate leaves through a pipe on systems, with several stages as the other side, at the bottom. In illustrated in the flow diagram in horizontal plug flow systems, the Figure 1 overleaf. feedstock travels as a plug of material at the rate it is fed in. It is digested and released at the opposite end. Vertical systems are simple and comparatively cheap to operate, but digestion time is harder to control and optimise. Horizontal plug flow systems are more expensive to set up and operate, but the digestion time can be optimised to improve efficiency.

Both ‘wet’ and ‘dry’ AD systems can be used. The wet system is most common, processing feedstocks with between 5 and 15% dry matter whereas dry AD systems can process feedstocks with over 15% dry matter. 66

Figure 1. Flow diagram of a typical AD system Feed stock storage and preparation The feedstock is stored and then mixed and blended in a vessel to provide a regulated mix of feedstock to the digester.

Digestion process The feedstock enters a sealed digester vessel where the material is broken down anaerobically by microorganisms for a set period, typically around 30 to 40 days.

Most digesters use a continuous flow process. Batch system designs can be used but are much less common.

Biogas Digestate The biogas produced is stored at relatively A wet AD system produces liquid digestate low pressure in a container, either in the with a dry matter content of approximately 5% to 7%. void space above a digester vessel or in a separate container alongside. Some systems separate the fibre from the liquid digestate using a mechanical Biogas can be used to generate electricity or separator to provide an additional to generate heat on site if there is demand. solid digestate.

A dry AD system produces stackable Biogas can also be treated to improve solid digestate. quality, enabling it to be exported to the gas grid (this is usually limited to larger plants). A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 67

4.4.2 Commercial opportunities inclusion rates for poultry manure The AD process has been used for are generally limited to around 20% many years in industry and on some of total feedstock. This is mainly UK cattle and other farms for the last because of its high nitrogen content, twenty years. Uptake has been which affects the chemistry and the driven mainly by the government microbial activity of the AD process. introducing financial support for The bacteria within the digester may infrastructure to generate renewable also be unable to break down lignin energy including Renewable in plants that may be present in used Obligation Certificates (ROC), Feed litter, if this is also added. in Tariff (FIT) and Renewable Heat Incentive (RHI). A further constraint – and the main reason why laying hen manure is The feedstock for the AD process can rarely included as a feedstock for AD be any biodegradable plant or at present – is because it contains animal matter and so on this basis, high levels of calcium grit which can poultry manure can be used. Based accumulate in the AD vessel unless on the example in Table 7 overleaf (at the system includes equipment to 20% dry matter), it is clear that trap the grit. Existing AD operators poultry manure has a higher gas are therefore likely to charge a gate yield than cattle manure but if used, fee at present for poultry manure 68

Table 7. Typical gas yields from different feedstocks Cattle manure Poultry manure Maize silage (25% DM) (20% DM) Gas produced per 50m3 85m3 210m3 tonne fresh weight

supplied to them, so this is unlikely digestate but since most AD plants to be a preferred option for egg include only a small proportion of producers at present. poultry manure in the feedstock, the analysis of the digestate is the result The secondary product of AD is of the ‘mix’, rather than the digested digestate (the residual product from poultry manure alone. Table 8 the digested feedstock). The volume opposite shows typical nutrient of digestate produced is typically just contents for AD digestate based on less than the volume of the feedstock RB209 figures28. input so it therefore represents a considerable weight of material.

Nitrogen is normally the most significant crop nutrient supplied by

28 https://ahdb.org.uk/nutrient-management-guide-rb209 A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 69

Table 8. Typical nutrient contents and MANNER-NPK estimates of nutrient value of digestate from farm sourced feedstock using RB209 figures29

Dry Total Total Total Total Total matter % N P O K 0 MgO SO Total 2 5 2 3 nutrient Type value kg/m3 or kg/t (£/m3)

Whole 5.5 3.6 1.7 4.4 0.6 0.8 5.1

Separated 3.0 1.9 0.6 2.5 0.4 <0.1 2.6 liquor

Separated 24.0 5.6 4.7 6.0 1.8 2.1 7.1 fibre

29 Whole digestate is unseparated material. Separated digestate are the two fractions produced after the digestate has gone through a mechanical separator. MANNER-NPK estimates are based on application to a sandy loam soil of farm-sourced digestate at either 50m3 per hectare by band spreading (trailing hose) for whole and separated liquor and 20 tonnes per hectare for separated fibre and incorporated by plough within 6 hours of application. Estimates were made for digestate applied in central England (annual rainfall of 650 mm) on 1 March growing a spring sown cereal. Nutrient price data were based on the AHBD GB fertiliser price data averaged over April 2018-March 2019; ammonium nitrate (34.5% N) at £263 per tonne; triple superphosphate (46% P2O5) at £325 per tonne; muriate of potash (60% K2O) at £273 per tonne. 70

New AD technology is currently treatment step to reduce the being developed that may offer more nitrogen levels in poultry manure. opportunity in future for using laying The system is currently being trialled hen manure as a feedstock at farm in Ireland and initial results are scale. expected to be published shortly.

Within the AgroCycle research At a larger scale, a new commercial project30 (with funding through the AD plant is being designed to EU Horizon 2020 Research and operate with laying hen manure Innovation Programme) Harper (only) in England. It is understood Adams University College is seeking that the plant will use 55,000 tonnes to develop a dry AD system capable of feedstock per year and that the of using only poultry manure as a biogas will be used in the gas grid. feedstock at farm scale. The AD The system will mix incoming laying system being trialled uses a low cost, hen manure (at 30% dry matter) with small scale rotating drum digester. the liquid fraction from the digestate This is capable of holding 40m3 of after nitrogen is removed from it to material inside a heated water jacket produce an ammonia sulphate using energy generated from a boiler fertiliser. A separate process is which uses some of the biogas intended to remove the calcium grit generated. It includes a pre- from the manure early in the

30 https://www.harper-adams.ac.uk/research/project/189/sustainable-business-models-in-food-waste-management-in- the-retail-sector A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 71

digestion process. The technology digestate requires additional solids has been developed by the American storage. Dry AD systems produce manufacturer DVO31 and the stackable solid digestate which installation is being developed by require similar clamp-type storage. Rika Biofuels32. Capacity for six months storage is normally required so that the 4.4.3 Key considerations digestate can be applied to crops at AD systems require both feedstock optimum plant growth stages. and digestate storage. Liquid feedstock storage requires a vessel The biogas produced by AD contains such as a slurry store. Solid feedstock, impurities which need to be such as poultry manure requires removed before the gas can be used storage in a structure with an for electricity generation. Gas impermeable base, retaining walls cleaning systems are offered by most and drainage collection. Liquid suppliers for this purpose. Further digestate can be stored in a tank of treatment is required to raise the concrete or steel construction, or in calorific value and remove other an earth lagoon. These generally contaminants to meet National Grid need to have a cover to control gas standards, but as this process has emissions. If the system separates the a relatively high cost it is limited to digestate, the fibre from the liquid larger scale AD plants.

31 http://dvoinc.com 32 www.rikabiofuels.com 72

Farmers can operate smaller AD digester systems typically range from systems without an environmental 250 to 500 kilowatt systems, permit, although registration with processing between 10,000 and the Environment Agency is still 20,000 tonnes of farm manures, required. An exemption is given slurry and crop feedstock per year. providing that only specified raw The capital investment involved materials are used (these materials typically ranges from around £1.4m include manures, slurries and plant to £2.5m, with return on investment tissue) and that the total quantity of mainly dependent upon income waste treated or stored at any time from energy sales, renewable energy does not exceed 1,250 cubic metres. support schemes and the sale of The digester must have a net rated digestate. thermal input of less than 0.4 megawatts. Digestate from farm- Government support for AD has based AD plants fed from agricultural tended to reduce over the years as sources can be applied to land for the industry capacity has grown. use as a fertiliser without a separate The incentive for developing on-farm exemption33. AD is now much more dependent on the financial returns that can be 4.4.4 Cost and returns achieved from using the biogas as Farm-scale biogas plants with wet energy on site.

33 www.gov.uk/guidance/waste-exemption-t24-anaerobic-digestion-at-premises-used-for-agriculture-and-burning- resulting-biogas A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 73 CASE STUDY ON ANAEROBIC DIGESTION AND DRYING – CHARLES MEAR A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 75

Charles and Jo Mear have a 28,000 bird free is a horizontal plug flow system which is 6 range egg production unit together with egg metres wide, 4 metres deep and 42 metres packing facilities and a mill for producing long with a capacity of around 1000m3. The feed using locally-grown wheat. They also feedstock is 60% maize purpose-grown crops manage arable crops on an enterprise of over (PGC) and 40% rye PGC grown on their farm 80 hectares in Bedfordshire. or supplied by neighbours. The digester generates 2,500 tonnes per year of solid Business diversification has been a key focus to digestate, after separation from the liquid ensure profitability and most recently, Charles fraction. The original intention was to include has managed the installation of a solar PV laying hen manure within the feedstock mix system and subsequently an anaerobic digestion with PGC, but the AD system design could (AD) plant for renewable energy and heat not operate with the build-up of calcium grit. production. The renewable heat from the AD plant is used to dry manure over a belt system The digestion process takes between 60 and supplied by Dorset Green Machine, model MB9. 65 days to complete. The digestate is separated through a screw press and the The AD system was installed in 2016 with liquid and solid fractions are land spread on biogas used for electricity generation through the farm for their fertiliser value, replacing a 165 kilowatt rated output generator. Around bought-in fertilisers. Some is also sold locally 10% of the electricity generated will be used as a fertiliser, soil improver or mulch to on-farm, the rest is fed into the grid. The digester farmers and allotment groups. 76

The farm has installed a belt drier to dry the Charles is developing a market for the laying hen manure and this operates off the residual solids produced on the farm and is renewable heat from the biogas fuelled CHP conducting trials based on dried manure generator. Two heat exchangers have been blends with the digestate solid fraction. The installed to provide heat to the drier. farm engages with local allotments and amateur gardeners and employs a consultant The birds are housed in flat deck systems to help develop products and markets. with verandas on both sides. The laying To help with the marketing of the dried cycles are staggered, so the farm generates organic fertiliser products, Charles is around 300 tonnes of manure every 6.5 experimenting with methods of further months. The drier has a throughput of processing including a shredder to reduce around 2.4 tonnes per day. The manure the particle size of the chicken manure prior entering the system is around 52% DM and it to drying, pellet extrusion and packaging. is dried to 85% DM. The dried manure is The farm has Leader Grant support for this. bagged into 2m2 bags for ease of handling and to reduce dust. A biological air scrubber The farm has plans to develop a local has been installed to reduce ammonia community education centre, which will emissions and dust, although this was not a invite local residents and schools to learn and legal requirement. actively participate in the farm project. This is planned in the coming years, with an education room including a heated A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 77

polytunnel facility running off the renewable heat from the generator.

The cost of installing the AD plant, the drying system and all associated ancillary equipment (including digestate liquor lagoons, heat exchangers, air scrubbers etc.) was around £1.8 million and it was not without problems. The initial aim was to get 7.2p per kilowatt hour through the RHI scheme. However, due to the design and build company going into liquidation prior to commissioning and rapid changes to government support, Charles has had to accept 3.2 pence. He has received no payments since the plant first became operational in April 2017 and this has had a huge impact on cashflow and therefore on the further development of the business. 5 CONCLUSIONS A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 79

For the vast majority of free range egg content being greater for spring than for producers, land spreading their manures and autumn applications. Poultry manures with a used litters is standard practice at present. higher dry matter content have more value The use of alternative methods is currently e.g. the nutrient value of an 80% dry matter rare. Producers who have sufficient land for manure is estimated at £41 per tonne. spreading benefit from the fertiliser values of the manures applied and the contribution it This range of manure values excludes any makes to the biology and structure of the costs of transport and spreading. Transport soil. However regular applications of poultry costs can be considerable, particularly for manure to the same land can result in an those exporting manures to other farms over-supply of nutrients and in turn to some distance away. This can erode the increased pollution risk. theoretical value of the manure (as shown) above and in practice result in little or no Based on a dry matter content of 50%, we income being obtained. In parts of the calculate the current nutrient value of country where there are high populations of poultry manure to be between £20 and £26 free range hens but comparatively low land per tonne, depending on the time of fertiliser requirements, this is already leading application and whether it is incorporated to concerns about the impacts of local into the soil within 6 hours or not. The most manure surpluses. valuable nutrients are phosphorus and potassium with the value of the nitrogen Legislation and codes of practice are already 80

in place to control the quantity and timing of The likelihood is that these developments poultry manures applied to land. The will exert further controls over land expectation is that these will become more spreading activities. For many farmers, this onerous in future. Key developments are the may mean that even maintaining the ‘status Farming Rules for Water (2018) and the Clean quo’ i.e. continuing un-changed with current Air Strategy (2019) which include the following:- land spreading practices will not be possible. Additional land areas will be needed for • Organic manure applications to be manures to be spread. In some parts of the planned to meet soil and crop country with high poultry populations, the nutrient needs; implications are likely to be most severe, particularly for those with insufficient land • Account to be taken of significant for spreading under their own control. risk areas for pollution; These developments may lead to renewed • Reasonable precautions to be interest in uses of manure other than for land taken to prevent runoff from spreading. Four alternative options have manure applications; been considered within this report and Table 9 on pages 83-85 summarises key • Mandatory design standards for new information relating to each. poultry housing in order to reduce ammonia emissions. A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 81

At present, the capital costs of activities such website and these will provide a basis for as combustion and anaerobic digestion are future decision-making. very high and therefore they are likely to be considered for ‘own use’ only by the very Evidence from the case studies indicates that largest free range egg producers. However, payments from these schemes can be much increased interest from farmers in the use of delayed and so this eventuality must be smaller systems may result in new planned and budgeted for. developments in lower capacity equipment, with the prospect of making them more Because of the lack of ‘alternative’ systems affordable to smaller producers. that are tailored to smaller producers at present, there may be a stronger case for For combustion and AD, revenue from considering a collaborative approach, whereby government schemes is important to a manure handling facility (such as combustion) financial success. For new enterprises, the is established at a central site in order to serve future of such schemes and the likely scale of the needs of a number of local producers, payments should be carefully considered at who would each supply manure to it. the outset because prices are regularly reviewed and government policy changes Details of future support that may be can be made. The latest rates for the Feed in available to farmers under the Clean Air Tariff (FIT)34 and the Renewable Heat Strategy are not yet available but assistance Incentive (RHI)35 can be found on the Ofgem with the capital costs of alternatives to land

34 www.ofgem.gov.uk/publications-and-updates/feed-tariff-fit-tariff-table-1-april-2019 35 www.ofgem.gov.uk/environmental-programmes/non-domestic-rhi/contacts-guidance-and-resources/ tariffs-and-payments-non-domestic-rhi 82

spreading and with the establishment of collaborative approaches to production and marketing could encourage and hasten change.

For manure systems which can produce heat (such as combustion and anaerobic digestion), there are additional opportunities to use a proportion of this to provide heat to free range houses at certain time of the year. This could provide additional benefits in terms of reducing ammonia emissions associated with housing, maintaining dry litter, improving bird welfare and reducing odour risk. A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 83

Table 9. Summary of key features of alternative poultry manure uses

Drying & Anaerobic Incineration Composting pelleting digestion

Medium – Drying Can be very low if High – likely to be equipment is windrow systems between around estimated to cost and existing High – typical £1.4m to £2m in around £2.50 per buildings or range is £1.4m Capital total, dependent bird for a house concrete bases are used. ‘In to £2.5m for 250 costs on whether a of 32,000, drying vessel’ systems to 500 kilowatt CHP and pelleting (equipment systems or a non-CHP for 64,000 birds alone) are likely to system is used is around be around £0.7m £4 per bird (equipment only)

Registration needed with Exempt from Environment environmental Agency but permitting unless exempt from bringing in environmental Animal by-prod- ‘higher risk’ permitting if ucts legislation wastes. Mixing poultry manures applies, APHA approval poultry manure and plant tissues Legislative enforced by is needed and with green waste are used; if waste and other key APHA. heat treatment would be treated and requirements Environmental to 70°C for at exempt. stored is less than (other than permit needed least 60 minutes Compliance with 1250m³ and if net planning (Part A2 (or equivalent) PAS100 is likely rated thermal consent) activity) regu- is needed to be needed to input is less than lated by the local ensure that 0.4 megawatts. authority recipients of the Digestate from compost do not farm-based require their own systems can be environmental applied to land permit without a separate exemption 84

Table 9 (cont). Summary of key features of alternative poultry manure uses

Drying & Anaerobic Incineration Composting pelleting digestion

Drying systems No lower limit for Large scale can be provided windrow systems needed (over for small units using existing 100,000 hens) Likely scale (12,000 birds) facilities. At least Large scale due to high or minimum whereas a medium scale (over 100,000 capital costs – size of minimum of (e.g. 64,000 birds birds) likely to be unless smaller operation 64,000 birds is as a minimum) is needed capacity systems likely to be likely to be become needed for needed for available in future pelleting in-vessel systems

Dried ‘bulk’ manure can attract a slightly higher sale price than fresh Compost, mainly Biogas which Energy which can manure, with for use in can be used to be used to lower transport agriculture, generate heat or generate heat or costs. Prices for horticulture or electricity for electricity for pelleted product for other land on-site use or on-site use or in Netherlands uses. The sale exported. The Final exported. vary greatly value may be digestate can products A residual ash is according to modest (e.g. £5 be spread to also produced nutrient content per tonne or less) land – nutrient which can be (£50-£220 per and if so the gate content varies sold to fertiliser tonne). High fee is the main according to companies or for prices possible income source the raw land-spreading if able to (see below) material mix successfully market bagged product to retailers A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 85

Table 9 (cont). Summary of key features of alternative poultry manure uses

Drying & Anaerobic Incineration Composting pelleting digestion

Gate fee charged on the incoming materials needed For new systems, For new systems, for mixing with income can be income can be poultry manure. obtained through Other obtained through This could range the Feed in income the Feed in Tariff None from £20 per Tariff (FIT) and sources (FIT) and the tonne for green the Renewable Renewable Heat waste to over £80 Heat Incentive Incentive (RHI) for materials that (RHI) require more regulatory and process control

Calcium grit Drying systems Poultry manure extraction are more suited alone is not systems must be to use with suitable for used. The high multi-tier composting nitrogen content housing and because of its of poultry The are cheap to high nitrogen manure generally recommended operate if Limits and content. restricts its manure dry exhaust air from dependencies Mixing with a inclusion rate to matter content the house can carbon-rich 20% of an ‘AD is at least 55% be used to dry material is mix’. Supply of the manure. needed to laying hen Design of free achieve the manure to other range sites will optimum AD plants is likely determine the C:N ratio to require ‘gate feasibility of this. fee’ payments 86 photographs

Photo 1. Case study – James Baxter Photo 2. Typical farm scale wet AD process

Feedstock Biogass Liquid store storage digestate (silage storage clamp)

Feedstock mixer vessel

Photo 3 Typical drying system set up A BRITISH FREE RANGE EGG PRODUCERS ASSOCIATION SUSTAINABILITY SCHEME REPORT 87

Photo 4 Small pellet press which can process 400 kg per hour

Photo 5 Distributor spreading manure onto the drying belt Photo 6 Case study – Charles Mear

Manure drying (green building) using waste heat from anaerobic digestion. The dried manure is bagged for easy of handling and storage