Organic So oil Fertility: General Princciples and New Reseearch

Richard Smith Vegetable Crop and Weed Science Farm Advisor University of Cooperative Extension Monterey County Organic S oil Fertility • We will focus on organic fertility of vegetable crops • We will mostly discuuss • Obviously other nutrients are important, especially phosphor us and • Before we spend the time in this discussi on on ni trogen we will bri efl y discuss and potassium Soil Phosph horus Levels bicarbonatebicarbonate--exextractable (ppm)

Crop Response Response Response likely possible* unlikely Lettuce and <40 40 – 60 > 60 Celery Other cool- < 25 25 – 35 > 35 season vegetables Warm-season < 15 15 - 25 > 25 vegetables

* especially in cold soils Soil Potass sium Levels ammonium acetate--extractableextractable (ppm)

Crop Response Response Response likely possible unlikely Celery < 150 150 – 200 > 200 Other cool-season < 100 100 – 150 > 150 vegetables Potato, tomato, < 150 150 – 200 > 200 pepper CbitCucurbits < 80 80 – 120 > 120 Phosphorus anda Potassium • Both of these nutriennts can be monitored and managed with the use of soil tests • There are several orgganic sources of these nutrients • High soil pH reducess the availability of bone and rock sources of phosphorus • VbldiVegetable production systems can over time build up high levels of soil phhhosphorus Organic Soil Fertility • Nitrogen is particularly problematic because of various forms it occurs in and transformations it goes through • nitrogen ( and ammonium) is the plant available form of N in the soil • Lar ge quant i ti es of N aasoelso exi sts in complex forms in soil which are not available for ppglant growth • The challenge in organic agriculture is to get sufficient mineraal N from non -mineral N sources Nitrogen Cycle Crop residue, Compost, Soil Organic Matter Most soil N is in this form (1000 ––33000 lbs N/A)

Death Mineralization* Death

+ CEC NHH4

Plants Nitrificcation Microbes

- Amino NOO3 * Mineralization is a key step in mmaking N available for plant growth It is dependent upon adequate soil temperatures (i.e. > 50 F) Sources of Nitrogen for Organic Ag • Storage • Recycling/Scavenging – Organic Matter – Prior crops, cereal cover • Legumes (N from air) crops – Green – Meat, Fish , Blood , , Bone • Vetches, clovers, peas – Alfalfa Meal – Seed Meals (cotton, soybean, etc) • Mined – , Guano – – GWtCtGreen Waste Compost • Seaweed Soil Test f or Ni troge n in O rga nic Systems • There have been many ideas proposed to test soil nitroggpen to ppppredict crop response in conventional and organic production systems • In conventional production the presidedress nitrate quiktick tes t measures nitrate, the dominant formformofNinthesoil of N in the soil • In organic production nitrate is not as useful of an indicator of nitrogen due to typically low levels of nitrate encountered in soil Comparison of Organic and Conventional Onions Hollister, 1996 80

70

60 Conventional 3-N 50 OO

40 pm N

pp 30

Soil 20 Organic 10

0 May May Jun Jun Jul Jul Jul Aug

Smith, 1996 Soil Nitrate in Organic Vegetable PdProducti ti2on 22001 - 2003 25

20 0-15 cm dry soil soil dry 15 -1 15-30 cm

10 µg g µg -N 3 5 NO 0

r1 1 2 r2 2 3 3 Y -Yr -Yr1 -Yr -Y -Yr -Yr Yr ll- r g ll r g-Yr2 ll- er-Yr1 te er a te n er a er-Yr3 m Fa n rin m F n ri m F nt i p i p W S um W S um Wi Sum S S Jackson, 2005 Nitrogen Soil Fertility • The amino sugar soil N test has not ppgroved to be a good predictor of N availability to crops • At present: the best iindication of available soil nitrogen status in organic systems is with total nitrogen: – Soils with less than 0.07% total N mineralize limited quantities of N for rapid crop growth – Soils with more than 0.15% total N can mineralize significant amounts of N during the crop cycle Nitrogen SoilS Fertility • As an example a soill with 0.07% total N contains 2,800 lbs N/A • Incubation studies have shown that during the summer about 1% of soil organic N mineralizees/month • For a 60 day growth cycle that would be: 2800lbsNx10%x2,800 lbs N x 1.0% x 2 months = 56 lbs N/A • This is about 1 lb N/A/day Nitrogen SoilS Fertility • The nitrogen that min neralizes from the organic matter is the “background” nitrogen level that evvery soil provides for plant growth • A key goal in organicc production is to build up the levels of organic matter which increases the levels of stored N which can be mineralized for plant growth Impacts of Organic Soil Building on Nitrogen Storage in Soil Soil Type Manaagement Total Soil N % Clay Loam Organic 0.17 Clay Loam Conventional 0.14 Loam Organnic 0140.14 Loam Conventional 0.11 Fine Sandy Loam Organic 0.12 Fine S and y L oam Conventional 0060.06

Smith, 2003 Impacts of Organic Soil Building on Nitrogen Storage in Soil Soil Type Manaagement Total Soil N % Clay Loam Organic 0.17 Clay Loam Conventional 0.14 Loam Organnic 0140.14 Loam Conventional 0.11 Fine Sandy Loam Organic 0.12 Fine S and y L oam Conventional 0060.06

Smith, 2003 Generalized Trend Line: Mineral Nitrogen MMade Available from Soil Organic Matter itrogen A/Day NN //

N 1.5 _ 1.0 lbs Mineral 050.5

0 10 Weeks Nitrogen Requirement of Vegetables Seasonal Uptake Low total N content Medium total N High total N content < 120 lb s/ acre conntttent > 200 lb s/ acre 120-200 lbs/acre Baby greens Carrrot Broccoli Beans Corn, sweet Cabbage Cucumbers Gaarlic Cauliflower Radish Lettuce Celery Spinach Mellons Potato Squashes Onion Peppers Tomatoes Nature of Veg getable Crops

• Rapid growth from 30 to • High peak demand for N 60 days following • Can be as high as 44--55 lbs planting Nitrogen/Acre/day

100,000

90,000

80,000

70,000

60,000

50,000

40,000 Fresh (Lbs) Poly. (Fresh (Lbs)) 30,000

20,000

10,000

0 20 30 40 50 60 70 Crux of Nitrogenn Fertilization of Organic Horticultural Crops • Some crops may be able to achieve economicallyyp accepttable yield from mineralization of soil organic matter • Most of our key cropps will generally need greater quantities of available mineral nitrogen to achieve eeconomically viable yields Nitrogen from Green Manures

• This can be an economical source of N • Cereal cover crops recycle and scavenge N from theesoile soil • Legumes fix nitrogen from the air • There are some k ey idiissues regarding N from cover crops that needs to be kept in mind Cover Crop Depends upon C:N; lignin and Polyphenols

Microbes Microbes

Available Typically <<1010--3030%% of cover crop N is taken up by the first subsequent Mineral Crop* Nitrogen

* A good deal of cover crop N remains in the system and can can be taken up in later years (i.e. 7373%% - Jackson, 2000)2000) N Release Pattern from Cover Crops

18 Legume Mix 16 Mustard Oats 14

(ppm) 12

10 l Nitrogen

aa 8

6

otal Miner otal 4 TT

2

0 0112539 53 67 Days After Incorporation of Cover Crop Smith & Brennan, 2003 Nitrogen release from cover crop residue based on the N content Percent N Examples of Cover Crops Nitrogen Release in Cover Crop

Will Tie up N 0.5 Cereal Straw Will Tie up N 1.0 Cereal Straw Will Tie up N 1.5 Cereal at heading May Tie up N* 2.0 Cereal pre heading May Tie up N* 2.5 Mustards at heading and Imm. cereal Will Release N 3.0 Mustards, legumes and juvenile cereal Will Release N 3.5 Legumes and immature mustards Will Release N 4.0 Legumes 2006 & 2007 Cover Crop & Trial

Year Bi omass N in Tops N in Tops T/A Percent lbs/A 2006 3.21 3.1 194.5 2007 3371.71 212.1 153. 4 Smith and Muramoto, 2007 2006 Soil Mineral Nitrogen CCICover Crop Incorpora tion tPltiBto Planting Broccoli

12.00 With cover crop No cover crop

10.00 SEM)

8.00 mg/kg +/- (( 6006.00

4.00 ineral N ineral N MM 2.00 Total

0.00 21-FbFeb 1-Mar 9-Mar 16-Mar 23-Mar 31-Mar 6-Apr 13-Apr 20-Apr 2007 Soil Mineral Nitrogen Cover Crop Incorporation to Planting Broccoli

16. 0 14.0

/- SEM 12.0 10.0

mg/Kg + mg/Kg 8.0 6.0 With cover crop ineral N 4.0 mm No cover crop 2.0

Total 0.0 27‐Mar 29‐Mar 31‐Mar 2‐Apr 4‐Apr 6‐Apr 8‐Apr 10‐Apr 12‐Apr 14‐Apr Date Percent of Cover Crop Nitrogen Mineralized at 8 Weeds

40

35

30

25

20

15

10

5

0 0 1 2 3 4 5 6 -5

Hartz, unpublished 2006 Nitrogen in Broccoli Biomass lbs/A At Harvest

200.0

180.0

160.0

bs/A 140.0

120.0

100.0 omass N l ii 80.0 No cover crop 60.0 With cover crop

roccoli B 40.0 BB 20.0

0.0 0 75 150 225 Application Rate lbs N/A 2007 Nitrogen in Broccoli Biomass lbs/A At Harvest

200.0

180.0

160.0 bs/A ll 140.0

120.0

mass N 100.0 oo No cover crop 80.0 With cover crop 60.0 ccoli Bi

oo 40. 0

Br 20.0

0.0 0 75 150 225 Organic Fertilizer Application Rate lbs N/A Broccoli Yield 2006 Trial

9.0 Without cover crop 8.0 With cover crop

(+/-) 7.0

6.0

5.0 ns/A) SEM oo

4.0

3.0 oli yield oli yield (T cc 2.0 Broc 1.0

000.0 075150 225 Organic Fertilizer Application Rate lbs N/A Broccoli Yield 2007 Trial

10.0

9.0 Without cover crop

8.0 With cover crop (+/-) MM 7.0

6.0 ons/A) SE 505.0 TT

4.0

3.0 oli yield oli yield ( cc 2.0 Broc 1.0

0.0 075150 225 Organic Fertilizer Application Rate lbs N/A Summary of Nitrogen from Cover Crops • Cover crops can provide substantial amounts of N for plant growth • However, supplemental fertilization was needed for maximum yield • The amount and rate of nitrogen made available from the coover crop depends on its nitrogen content Mineralization of Mineral Nitrogen from Manures and Compost

Manures and composts are widely used in orgaanic systems, but what can they provide with regards to nitrogen nutrition Characteristics of Compost/Manures Material Total N C/N Ratio Pelletized manure 474.7 454.5 Aged poultry manure 3.1 9.1 Poultry compost 3.8 5.7 Aged feedlot manure 202.0 12. 4 Feedlot manure compost 2.2 11.4 Yard waste compost 1.6 14.4 Yard waste compost 101.0 12. 0 Hartz et al, 2000 N Mineralization Manures and Compost • ItIn a two year st tdudy ooffth the mi nerali zati on rate of organic amendments, nitrogen was recoveredid in a f escue crop as fllfollows: Material Mean N recovery High N recovery Percent Percent Manure 11 27 Composted Manure 615 Composted Yard Waste 2 6 Hartz et al, 2000 Mineralization of Mineral Nitrogen from Manures and Compost Summmary • Mineralization of mineral nitrogen from manures and compos st can provide limited amounts of readily available N for high N demanding horticultuural crops • These materials play a larger role in soil building and provide a long-term source of N that contributes to total soil nitrogen content and that beh aves the same as soil organic matter Mineralization of Mineral Nitrogen from Manures and Compost Summmary • Composts and manures are good sources of phosphorus and ppotassium

Material Phoosphorus Potassium Manures and composts 1.6 – 2.6 0.5 – 3.0 Yard Waste Composts 020.2 – 030.3 060.6 – 141.4 Mineralization from Dry Organic Fertilizers Net N Mineralization Percent of Initial Product Temperature 1 Week 4 Weeks 8 Weeks °F Pelleted Poultry 59 41621 Manure 77 10 23 36 Fish Powder 59 51 55 61 77 48 60 64 Feather Meal 59 42 56 59 77 50 64 63 Blood Meal 59 41 60 64 77 51 67 70

Hartz & Johnstone 2006 Percent of Nitrogen Mineralized Across Fertilizers

Hartz & Johnstone 2006 Percent of Nitrogen Mineralized Across Temperatures

Hartz & Johnstone 2006 Incubation Studies of Dry Organic Fertilizers

• There was relativelyyp rapid mineralization in the first two weeks • This was due to en zymatic hydrolysis of urea and simple proteins (labile forms of N) • Even at low temp peratures the labile forms of N were made available and exhausted in two weeks • There was a slow rate of militifineralization affter two wee ks that was similar to decomposition rates of soil organic matter (complex organic cNforms)c N forms) Field Study with Organic Fertilizers Transplantted Broccoli

Conducted in Watsonville From May to July Smith 2001 Soil Temp peratures

72 70

68

66 64

62 1 5 9 13 17 21 25 299 33 37 41 45 49 53 57 61 65 Organic Fertilizer Treatment Applic cation Timing

Treatment Preplant Top Top Top Total dress dress dress May 8 May 31 June 7 June 14 Untreated 0 0 0 0 0 Fert Treat No. 1 45 45 45 45 180 FFtTtN2ert Treat No. 2 90 0 45 45 180 Fert Treat No. 3 135 00004545 180 ------Fertilizers------1) Meat Meal 8 -5-1 2) Feather Meal 12-0-0 3) Blood Meal 1313--00--00 4) Guano/ 77--00--00 NitrateNitrate--NitrogenNitrogen in the Soil of 135135--4545 Fertilizer Treatments

50

40 Guano/Chicken 30 2nd Fertilizer Application 20 Blood 10

0 1234567 Yield Evaluation: Total Number of Heads

200

150

100

50

0 12345 Untreated Meat Feather Blood Guano/ Meal Meal Meal Chicken Yield Evaluation: Total Weight of Heads

60 50 40 30 20 10 0 1 2 3 4 5 Untreated Meat Feather Blood Guano/ Meal Meal Meal Chicken Comparison of Materials and Timing Total Weig ght of Heads

70 60 50 lbs) 40 30

eight ( eight 20 WW 10 0 123456 ------BloodBlood MealMeal------Guano/ChickenGuano/Chicken------45 9090--4545 135 45 90-90-4545 135 4x 2x 4x 2x Summary of Field Study with OOrganic Fertilizers Transplanted Broccoli

• Guano Chicken gave the most rapid release of nitrogen • Other forms of nitrogen apparently released nitrogen too slow to meet N demand by broccoli • Applying nitrogen early in the growth cyclthhihle gave the highessttild yield • This was due to providing sufficient time for the nitrogen to mineralize and meet the demand for N by the broccoli crop • irgnfrom nitrogen mineralization of affects thespeed of content greatly The initialnitrogen organic fertilizers

from

%ofNm% of N mineralizem ed % ofofN N m ineralized 100 100 - -20 20 40 60 80 20 20 40 60 80 0 0 01 02 035 30 25 20 15 10 5 0 01 20 15 10 5 0 Initial N content (%) Initial C/N ratio fff 28 day incubation full field season 28 day incubation ull f ield season Mineralization Characteristics of Liquid Orga anic Fertilizers Liquid O rganniic F ertili zers

• Liquid organic fertilizers are convenient to use and can be injected througgph drip systems • They have challenge es in applying through drip systems (plugging and losses) • They are expensive pper unit of nitrogen ($4($4--70/lb70/lb of N) Net N Mineralization Liquid Fertilizers Percent of Initial @ 59 °F

Product Material %m% mmineral N 1 week 2 week 4 week @ time zero Agrolizer Fish 5. 12 actual N 60labelN6.0 label N 70 69 75 83

Biolyzer Grain 2.59 actual N Fermentation 12 34 40 50 2.5 label N Phytamin 434 Guano, Fish 3.48 actual N 4.0 label N 63 74 78 79

Phytamin 421 Soy Meal 3.96 actual N Plant Extracts 24 62 71 78 4.0 label N

Hartz, unpublished Liquid Organ nic Fertilizers Summary • These materials are unique in the amount of mineral nitrogen immediately available • They mineralize quickly and can rapidly meet crop nitrogen nneeds Effectively Fertilizing with Organic FtilFertillizers • Orggganic soil management is complex • To do a good job it is important to be aware of the interactiion between the mineralization characteristics of soil organic matter, soil aamendments, crop residues and fertilizers, as well as crop N demand • Understanding the impacts of soil temperatures, soil mo oisture and irrigation practices on the above is critical Effective Synchrony Between Mineralization fr rom the Various Sources and Crop Demand

Fertilizer Mineralization Crop Demand Cover Crop

/Day 5.0 Mineralization AA

4.0 Soil organic matter mineralization en lbs N/ 3.0 gg

2.0 ral Nitro

ee 1.0 Min 0 10 WEEKS Effective Organiic N Fertilization Programs • Soil building practices can provide useful amounts of N • Supplemental N must be provided in most cases to supply the ppeak N needs of shallowshallow--rooted,rooted, high--NN demanding cool season vegetable croops Effective Organiic N Fertilization Programs • Understanding the release characteristics of N sources is key • Understanding the influence of temperature and moi isture on N mineralization is essential • These two factors must be considered in conjunction with crop demand Effective Organiic N Fertilization Programs • At present there is no effective soil N test in orggyanic systems • Growers have settled on N fertilizer programs by years oof trial and error • The fertilization programs that they have settled on probably hhave a cushion built in to assure sufficient N for crop growth Effective Organiic N Fertilization Programs • The costs of organic sources of N are ppgggushing growers to ggyreater efficiency • Cost per pound of nitrogen in organic fertilizer: • Dry organic fertilizers – typically >$2.00 • Liqu id organi c f ertiliz tilizers – $4-70 For Further Information

• Organic Soil Fertility Management Syypmposium January 15, 2009, UC Davis – [email protected] Publications

• Nitrogen sources for organic vegetable crops – Mark Gaskell and Richardd Smith, 2007 – http://vric.ucdavis.edu/slectnewtopic.organic.htm

• Soil fertility management for organic crops – MkGkllRihdSMark Gaskell, Richard Smmithith an d o thers, 2006 – http://anrcatalog.ucdavis.edu/OrganicVegetableProducti oniClifinCaliforn i/ia/7249.aspx • http://cemonterey.ucdavis.edu/ Thank yyyou for your attention