Soil fertility & tillage management for organic farming systems

Transcription

1 Soil fertility & tillage management for organic farming systems C.R. Crozier, A. Meijer Soil Science Dept. C. Reberg-Horton, G. Place Crop Science Dept.

2 U.S. Markets Market potential organic production increasing 20%/yr organic grains incr. >20%/yr organic meat & poultry incr. >75%/yr NC Markets Demand at 2 NC mills for 150,000 bu corn & 150,000 bu wheat annually (4,000 ac) Largest certified organic egg farm in U.S. is Red Hill Farm in Nash Co.

3 NC Organic Grain Production Acreage 1800 ac certified 1800 ac in transition <1% of total grain acreage Economics (typical) Prices 1.5 to 2x conventional Yields 2/3 to 3/4 conventional Rotations Grain only: corn/soy, corn/wheat (oats)/soy Grain/vegetable Grain/tobacco Grain/forage not common in NC, but recommended elsewhere

4 Organic agriculture? Farm with >$5,000 annual sales Must be certified by a USDA-accredited certifying agent Farm with <$5,000 annual sales Exempt if direct market to end user Must comply with regulations May not label products as certified organic

5 Organic agriculture basics USDA Nat. Organic Program (NOP), years with no prohibited inputs Distinct, defined boundaries (+ buffer) Plan & document compliance Inputs Cultural practices

6 Soil fertility management issues Objective rules: allowed (most natural, a few synthetics) (simplified list) Prohibited (most synthetic compounds, chemically processed ores) No GMO s Subjective: No seed coatings with prohibited substances Conditional inputs (raw manures, synthetics)

7 Soil tillage / management issues Objective rules: Crop rotation No field burning to dispose of residue Subjective Minimize soil erosion Maintain or improve soil physical, chemical, and biological condition (soil quality?)

8 NC Organic Grains Extension Programs Organic Grain Production Guide Website: production & marketing info Target farmer focus groups Coastal plain, Tidewater Field tours target farms & research stations Meetings Funding Z. Smith-Reynolds Foundation Golden Leaf Foundation NC Ag Foundation State commodity groups USDA-SARE?

9 Fertility management recomendations Plan to supply adequate nutrients & avoid excesses Calculate nutrient needs & inputs Monitor soil test levels & adjust inputs Periodic plant tissue analysis to adjust inputs Maintain soil quality (physical, chemical, & biological condition) Monitor soil organic matter (humic matter) Monitor soil CEC & ph Maintain yield records

10 3. Compost bins at a swine farm Soil fertility options

11 Lime & macronutrient supply options Allowed Not allowed (verify with certifier) Lime Ground limestone, dolomite Hydrated or burnt lime N Legumes, manures*,animal & plant by-products*, mined NaNO3* Synthetic fertilizers, sewage sludges, municipal composts P K Manures*, rock phosphate, animal by-products (bone meal, oyster shells, fish scraps, leather) Manures, plant by-products, ash*, mined sources depending on processing* Processed rock phosphates KCl* if chemically processed or if excess soil chloride, KNO 3 * restrictions

12 Secondary nutrient supply options Allowed (verify with certifier) Not allowed S Manures*, plant by-products, mined sources (elemental S, gypsum, Epsom salt, sulfate of potash, sulfate of potash-magnesia) Synthetic fertilizers (ammonium sulfate, N-S solutions) Ca Lime, gypsum, bone meal, ash* Ca(OH) 2, CaO, Ca(NO 3 ) 2 Mg Dolomitic lime, Epsom salt, sulfate of potash-magnesia, bone meal, cottonseed meal, wood ash Synthetic fertilizers *Restrictions include no ashes of manures, apply manures based on nutrient management guidelines.

13 Micronutrient supply options Allowed (verify with certifier) Not allowed B Cu Mn Zn Co, Fe, Mo, Se Manures*, animal & plant byproducts, soluble B fertilizers* Manures*, animal & plant byproducts, sulfates & oxides* Manures*, animal & plant byproducts, sulfates & oxides* Manures*, animal & plant byproducts, sulfates & oxides* Manures*, animal & plant byproducts, sulfates, oxides, carbonates, & silicates* Chlorides Chlorides Chlorides Chlorides, nitrates *Restrictions include need to document nutrient deficiency for soluble micronutrients & apply manures based on nutrient management guidelines.

14 Sampson Co., Chipley sand Limed based on soil test recommendation, + turkey litter compost Soil ph '90 '92 '93 '94 '95 '96 '97 Year

15 Soil Test Humic Matter (%) Sampson Co., Chipley sand (Aquic Quartzipsamments) Received composted turkey litter annually Consider soil test records to document soil quality maintenance. 0.0 '90 '92 '93 '94 '95 '96 '97 Year

16 Soil CEC (meq/100 dm3) Sampson Co., Chipley sand Composted turkey litter annually, lime based on soil test recommendation Consider soil test records to document soil quality maintenance. 0 '90 '92 '93 '94 '95 '96 '97 Year

17 Soil Test P (x 2.14 = lb/ac) and K (x 3.5 = lb/ac) Indexes Sampson Co., Chipley sand Over-reliance on manures is of concern to accredited certifiers. This example prior to 2000 USDA rules. (prior to '96, all P index values were 166+) 0 '90 '92 '93 '94 '95 '96 '97 Year P K

18 Soil Test Zn (x = lb/ac) & Cu (x = lb/ac) Indexes Sampson Co., Chipley sand Received composted turkey litter annually Over-reliance on manures is of concern to accredited certifiers. This example prior to 2000 USDA rules. Zn Cu 0 '90 '92 '93 '94 '95 '96 '97 Year

19 Nutrient Removal & Supply Corn lb/135 bu Broiler litter Layer manure Feather meal Swine/ vermicom post lb nutrient if apply 100 lb PAN / ac Mush room compost N (3.3 t/ac) 100 (1.9 t/ac) 100 (0.8 t/ac) 100 (7.4 t/ac) 100 (9.9 t/ac) P 2 O K 2 O S Zn Cu Lime -300*

20 Green manures in NC Winter annuals (hairy vetch, crimson clover) lb N/ac Best if planted Sept/early Oct in coastal plain Overseed prior to soybean leaf drop Total cost $0.50 to $2+/lb N, depending on productivity Summer annuals (cowpea, sunhemp, etc.) All require adequate ph, other nutrients, drainage

21 Hairy vetch & crimson clover in 2007 corn N response trials (not certified organic fields) Tyrrell Co. Washington Co.

22 Vetch vs crimson clover in poorly drained soils? Tyrrell Co., Hyde silt loam fallow / rye / clover / vetch Dry Matter (lb/ac) fallow / rye / clover / vetch C:N ratio fallow / rye / clover / vetch N (lb/ac)

23 Legume selection Farmer focus group requested alternative to vetch to avoid weed potential; certified wheat seed industry concerned. Crimson clover less suitable for poorly drained tidewater soils? Other species (winter pea, lupine)? Currently working with independent scouts to assess vetch weed problem

24 Corn, Tyrrell Co, 2007 Grain Yield (bu/ac) fallow rye clover vetch Note: vetch as effective as 50 lb fertilizer N LSD 0.05 = Fertilizer N (lb/ac)

25 Grain Yield (bu/ac) Corn, TRS, 2007 Note: best clover stands (overseed) as effective as 50 lb fertilizer N. 140 fallow a 120 clover (overseed) b 100 clover (drill) b LSD 0.05 = c cd cd 60 e de 40 e e 20 0 MG3 MG4 MG Fertilizer N (lb/ac) (or cover pl date)

26 Legume cost estimates Crimson Clover Hairy vetch $/ac Seed + innoculum Seeding Extra cultivation/herbicide Total $ $ Assume 25 lb seed/ac at typical seed, innoculum, & aerial seeding price. Minimal additional cost to kill cover crop above normal field preparation cost.

27 Legume cost estimates Productivity level lb N/ac Crimson clover Hairy vetch If $40/ac If $70/ac If $50/ac If $85/ac $/lb N For comparison, 30% UAN solution at $300/ton is $0.50/lbN.

28 Aerially overseeded winter annual legumes? Adequate stands? i.e. risk of poor seed-soil contact? Biomass & N fixation amounts? Risk of excess growth interfering with soybean (or cotton) harvest?

29 Tillage & other weed control Pre-plant Blind cultivation after planting Rotary hoe Spring tine harrow Cultivation between rows Rolling cultivator Sweeps

30 Flex tine harrow & rotary hoe

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32 Other weed control Flaming Organic herbicides Vinegar, other plant products No-till with cover crop mulch

33 No-till possible? Rodale Institute, Pennsylvania; NC field trials planned for 2008.