The Strategic Land Group Ltd Land at Hawarden Road, Penyffordd
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The Strategic Land Group Ltd Land at Hawarden Road, Penyffordd, Flintshire Agricultural Land Classification and Soil Resources March 2016 Reading Agricultural Consultants Ltd www.readingagricultural.co.uk 1 Introduction 1.1.1 Reading Agricultural Consultants Ltd (RAC) is instructed by The Strategic Land Group Ltd to investigate the Agricultural Land Classification (ALC) and soil resources of land at Hawarden Road, Penyffordd by means of a detailed survey of soil and site characteristics. 1.1.2 Guidance for assessing the quality of agricultural land in England and Wales is set out in the Ministry of Agriculture, Fisheries and Food (MAFF)/Welsh Office Agriculture Department revised guidelines and criteria for grading the quality of agricultural land (19881). 1.1.3 Agricultural land in England and Wales is graded between 1 and 5, depending on the extent to which physical or chemical characteristics impose long-term limitations on agricultural use. The principal physical factors influencing grading are climate, site and soil which, together with interactions between them, form the basis for classifying land into one of the five grades. 1.1.4 Grade 1 land is excellent quality agricultural land with very minor or no limitations to agricultural use, and Grade 5 is very poor quality land, with severe limitations due to adverse soil, relief, climate or a combination of these. Grade 3 land is subdivided into Subgrade 3a (good quality land) and Subgrade 3b (moderate quality land). Land which is classified as Grades 1, 2 and 3a in the ALC system is defined as best and most versatile agricultural land. 1.1.5 The whole of England and Wales was mapped from reconnaissance field surveys in the late 1960s and early 1970s to provide general strategic guidance on agricultural land quality for planners. This Provisional Series of maps was published on an Ordnance Survey base at a scale of One Inch to One Mile (1:63,360). The Provisional ALC map shows the site as undifferentiated Grade 3 land. However, these maps are not sufficiently accurate for use in assessing individual fields or sites, and should not be used other than as general guidance. 2 Site and Climatic Conditions 2.1 General Features, Land Form and Drainage 2.1.1 The site is located to the north of Penyffordd, to the east of the A550 and west of Hawarden Road and its associated residential development. The site comprises a single grassland field extending to 1.4ha which is bordered on all sides by substantial hedgerows, with further grassland to the south. The site slopes gently downwards from 113m above Ordnance Datum (AOD) at the junction of the A550 and Hawarden Road to 110m AOD in the south-east. 1 MAFF/WOAD (1988). Agricultural Land Classification of England and Wales. Revised guidelines and criteria for grading the quality of agricultural land. MAFF Publications. RAC 7156 1 25/02/2016 2.2 Agro-climatic Conditions 2.2.1 Agro-climatic data for the site have been interpolated from the Meteorological Office’s standard 5km grid point data set at a representative altitude of 112m AOD, and are given in Table 1. The site has a cool and wet climate, with a large number of days at which soils are at field capacity, and moderately small to moderate moisture deficits. Table 1: Local agro-climatic conditions Average Annual Rainfall 803 mm Accumulated Temperatures >0°C 1,345 day° Field Capacity Days 182 days Average Moisture Deficit, wheat 86 mm Average Moisture Deficit, potatoes 72 mm 2.3 Soil Parent Material and Soil Type 2.3.1 The British Geological Survey2 maps the solid geology as that of the Gwesphyr sandstone formation which is a fine grained sandstone formation with subordinate Argillacaceous rocks. Along the eastern edge of the site, the bedrock geology is shown as the Bowland shale formation, which is a Carboniferous Mudstone. Superficial deposits of glacial till have been mapped across the entire site. 2.3.2 The Soil Survey of England and Wales soil association mapping3 (1:250,000 scale) shows Brickfield 3 Association soils across the site. This association consists of loamy and clayey surface-water gley soils over a greyish till or Head derived from Carboniferous and other Palaeozoic sandstones and shales. The predominant loamy textures are due to the preponderance of sandstone in the drift. The soils are seasonally or severely waterlogged (Wetness Class (WC) IV or V) although can be 4 improved to WC III with underdrainage . 2 British Geological Survey (2015). Geology of Britain viewer, http://mapapps.bgs.ac.uk/geologyofbritain/home.html 3 Soil Survey of England and Wales (1984). 1:250,000 scale soil association mapping, Sheet2 – Soils of Wales 4 Rudeforth C.C. et al (1984). Soils and Their Use in Wales. Soil Survey of England and Wales Bulletin No. 11. RAC 7156 2 25/02/2016 3 Agricultural Land Quality 3.1 Soil Survey Methods 3.1.1 Three soil profiles were examined using an Edelman (Dutch) auger at an observation density of more than one per hectare which is more intensive than the standard survey density for detailed ALC. One observation pit was also excavated to examine subsoil structures (as shown in Appendix 1). The locations of observations are indicated on Figure RAC7156-1. At each observation point the following characteristics were assessed for each soil horizon up to a maximum of 120cm or any impenetrable layer: • soil texture; • significant stoniness; • colour (including localised mottling); • consistency; • structural condition; • free carbonate; and • depth. 3.1.2 Soil Wetness Class (WC) was inferred from the matrix colour, presence or absence of, and depth to, greyish and ochreous gley mottling, and slowly permeable subsoil layers at least 15cm thick, in relation to the number of Field Capacity Days at the location. 3.1.3 Soil droughtiness was investigated by the calculation of moisture balance equations (as shown in Appendix 2). Crop-adjusted Available Profile Water (AP) is estimated from texture, stoniness and depth, and then compared to a calculated moisture deficit (MD) for the standard crops wheat and potatoes. The MD is a function of potential evapotranspiration and rainfall. Grading of the land can be affected if the AP is insufficient to balance the MD and droughtiness occurs. When a profile is found with significant stoniness, sufficient to prevent penetration of a hand auger, then it is assumed, for the purposes of calculating droughtiness, that similar levels of stoniness continues to the full 1.2m depth considered, unless an observation pit excavated in the vicinity shows otherwise. 3.2 Agricultural Land Classification and Site Limitations 3.2.1 Assessment of quality has been carried out according to the MAFF revised guidelines (19881). Soil profiles have been described according to Hodgson (19975) 5 Hodgson, J. M. (Ed.) (1997). Soil survey field handbook. Soil Survey Technical Monograph No. 5, Silsoe. RAC 7156 3 25/02/2016 which is the recognised source for describing soil profiles and characteristics according to the revised ALC guidelines. 3.2.2 The main limitation to agricultural land quality is soil wetness and workability which limits most of the site to Subgrade 3a with a smaller area of Subgrade 3b. 3.2.3 Soil profiles of Subgrade 3a quality consist of approximately 30cm of dark greyish brown (10YR4/2 in the Munsell soil colour charts6) sandy clay loam topsoil which contains moderately developed medium sub-angular blocky peds with many visible roots and pores. The upper subsoil consists of a sandy clay loam or sandy loam which is dark greyish brown (10YR4/2) or brown (10YR5/3) with many medium prominent ochreous mottles and contains firm moderately developed fine sub- angular blocky peds. The lower subsoil consists of a brown (10YR5/3) slowly permeable clay which contains coarse angular blocky peds. 3.2.4 These profiles are either WC II or III, depending on the depth of the gleyed horizons and to the slowly permeable layer (Figures 7 and 8 of the ALC Guidelines1) which, when combined with a sandy clay loam topsoil in this FCD regime, gives a classification of Subgrade 3a for both wetness classes (Table 6 of the ALC Guidelines). 3.2.5 To the south of the site, the topsoil comprises 35cm of dark greyish brown sandy clay loam, with few, medium faint ochreous mottles. The subsoil consists of brown (10YR5/3) slowly permeable clay with many, medium, prominent ochreous mottles. This profile is in WC IV which, when combined with a sandy clay loam topsoil in this FCD regime, gives a classification of Subgrade 3b (Table 6 of the ALC Guidelines). 3.2.6 The areas of each ALC grade are given in Table 2 and are shown in Figure RAC7156-2. Table 2: ALC Areas Grade Description Area (ha) % of agric. land 3a Good quality 0.9 64 3b Moderate quality 0.5 36 Total Agricultural 1.4 100 6 Munsell Color (2009). Munsell Soil Color Book. Grand Rapids, MI, USA. RAC 7156 4 25/02/2016 Appendix 1: Soil Pit Photograph RAC 7156 5 25/02/2016 Appendix 2: Soil Profile Summaries and Droughtiness Calculations Droughtiness calculations are made according to the methodology given in Appendix 4 of the ALC guidelines, MAFF 1988. The end row represents the extent of the limitation posed by droughtiness; the end column the limitation from wetness. MDw= 86 MDp= 72 Wheat Calculation Potato Calculation Site stones TAv or EAv TAv or EAv AP (wheat) TAv AP (potatoes) No. Depth (cm) Texture Colour Mottle % (stones) % (soil) % mm (stones) % TAv (soil) % mm Gley SP WC Grade 1 0 30 SCL 10YR4/2 2 1 17 50.0 1 17 50.0 n n II 3a 30 50 SCL 10YR4/2 2 1 15 29.4 1 15 29.4 n n 50 70 SL 10YR5/3 mmp och 2 0.5 11 21.6 1 15 29.4 y n 70 75 SL 10YR5/3 mmp och 2 0.5 11 5.4 1 0.0 y n 75 120 C 10YR5/3 mmp och 2 0.5 7 30.9 0.0 y y Total (mm) = 137.4 Total (mm) = 108.9 MBw= 51.4 MBp= 36.9 Grade = 1 Grade = 1 Wheat Calculation Potato Calculation Site stones TAv or EAv TAv or EAv AP (wheat) TAv AP (potatoes) No.