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Southern SAWG--Building soil organically: how and why organic management works
- 1. Building Soil Organically:A Discussion of Practical Applications and Why They Work Bo Holland Screech Owl Farm Nelson County, VA Daniel Parson Oxford College Farm Oxford, GA
- 2. Approach to Production • • • • Diversevegetable operation About 3 acres production Intensive rotation in 12 quarter-acre blocks Marketing-CSA, Farmers’ Market, Restaurant sales
- 3. Organic Production “A productionsystem that is managed… to respond to site-specific conditions by integrating cultural, biological, and mechanical practices that foster cycling of resources, promote ecological balance, and conserve biodiversity”
- 4. Organic Fertility • Cultural:Rotation planning • Mechanical: Mined substances • Biological – Cover cropping in rotations – Plant and animal materials
- 5. Crop Rotations • Preventone crop from robbing nutrients • Allow maximum use of cover crops • Provide planning for fertility – Crop list applies directly to land area – You know what crop comes next – Possible to schedule liming or compost/mulch additions
- 6.
- 7. Field Rotation Plan2013 Field 1 Crop Rye Aisles Potatoes Sudex/Soybeans Garlic 2 Late Squash and Beans Wheat/Crimson Clover 3 Cabbage and Kale Buckwheat Cabbage and Kale Rye and Clover 4 Peppers/Eggplant Oats/Winter Peas 5 6 Beets Soybeans/Buckwheat Beets Rye/Crimson Clover Cucumbers/Squash Oats/Winter Peas 7 8 Arugula and Lettuce Soybeans/Buckwheat Arugula and Lettuce Rye/Clover Sweet Potatoes and Okra Rye and Clover 9 Early Beans, Basil, and Flowers Rye/Hairy Vetch 10 Broccoli Buckwheat Broccoli Rye and Clover 11 Melons and Winter Squash Oats and Winter Peas 12 Tomatoes and Late Lettuce Oats and Winter Peas 13 Carrots Soybeans/Buckwheat Carrots Season Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall
- 9. Fertility Needs N-P-K Field RotationPlan 2013 Field 1 Crop Rye Aisles Potatoes Sudex/Soybeans Garlic 2 Late Squash and Beans Wheat/Crimson Clover 3 Cabbage and Kale Buckwheat Cabbage and Kale Rye and Clover 4 Peppers/Eggplant Oats/Winter Peas 5 6 Beets Soybeans/Buckwheat Beets Rye/Crimson Clover Cucumbers/Squash Oats/Winter Peas 7 8 Arugula and Lettuce Soybeans/Buckwheat Arugula and Lettuce Rye/Clover Sweet Potatoes and Okra Rye and Clover 9 Early Beans, Basil, and Flowers Rye/Hairy Vetch 10 Broccoli Buckwheat Broccoli Rye and Clover 11 Melons and Winter Squash Oats and Winter Peas 12 Tomatoes and Late Lettuce Oats and Winter Peas 13 Carrots Soybeans/Buckwheat Carrots Season Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring Summer Fall 100-100-150 100-75-100 100-50-100 100-50-100 100-100-150 75-0-75 75-0-75 100-50-100 100-50-100 100-50-100 100-50-100 60-60-60 100-100-100 100-100-100 80-100-150 80-150-200 80-0-75 80-0-75
- 10. Converting a Conventional Recommendationto Organic • UGA online resource • Apply organic amendments for any recommendation • What is your preferred amendment? – Least expensive – Most effective – Locally available – On-farm resource like compost
- 11. Converting a Conventional Recommendationto Organic • Begin with your preferred amendment -or• The most balanced in N P K • Determine what else you need to apply • Convert amendment pounds/acre to pounds/field or pounds/bed
- 20. What Next? • • • • Calculate applicationfor each field Chart the amounts for each amendment Add up those amounts Put together an order – Plan ahead for when you need the materials – Get together with others in your local area
- 22. Make it Practical •Write down ‘recipe’ for each field • Make copies and keep in the barn • Convert to volume on fertilizing day – Weigh amendments into bucket/container – Mark bucket or container – Use markings each time to get it right • Load bags into cart and measure in field
- 24. Is it Effective? •Previous ‘one-size-fits-all’ approach – Wasting $ and resources? – Optimal crop response? • New system for 2013 – Spent the same $ on amendments – Improved crop response – Better use of resources
- 25. Building Soil Organically: PracticalApplications and Why they Work Southern Sustainable Agriculture Working Group Annual Conference Mobile, AL – January 17, 2014 25
- 26. Principle: Feed theSoil, and Let the Soil Feed the Crop • Soil life modulates the release of plant-available nutrients. • Its activity is intensified in the plant rhizosphere (next to root surfaces) to maximize efficient nutrient delivery. Provided that the soil life receives an adequate quantity and diversity of organic residues and plant root exudates. 26
- 27. Why it Works:Strengths of the Parson Produce Cropping System • 18 cover crops within a 13 year crop rotation. • Most cover crops grown to early flowering = optimum stage for quality and quantity of fresh OM. • Organic fertilizers (feather meal, True 7.5-5-7.5) also feed soil life. A vigorous cover crop of buckwheat occupies a fallow bed (foreground). Production crops grow in other beds (background). 27
- 28. Why it Works: someEnhancements to Consider Add compost to the system: Provides diverse inoculum of beneficial soil organisms. Good source of P – calibrate rate to deliver desired amount. Shorten interval between cover crop termination and vegetable planting: Consider no-till or strip-till planting into rolled cover. 28
- 29. Principle: the Lawof Return Give back to the soil what has been taken out through production and cultivation. (Sir Albert Howard, 1940s) Nutrients: replenish nutrients removed in harvest Organic Matter: feed the soil life – cover crops, manure, organic mulch, residues, etc. Harvest removes nutrients and organic matter from the cycle. Tillage burns up OM, promotes leaching. 29
- 30. Why it Works:Strengths of the System • Science-based translation of Clemson U. recommendations for organic fertilizer use. • Clemson U. rates for N and K are conservative, and thus sufficient. • Crop- and field-specific NPK rates optimize outcomes. • Slow-release organic fertilizers can be applied pre-plant – no side-dress needed. Tomatoes may require more K and less N than leafy greens, and are amended accordingly. 30
- 31. Why it Works: someEnhancements to Consider Nitrogen recommendations ignore soil mineralization and cover crops: Can reduce N inputs by 0.5X the total cover crop N. Healthy, living soil can provide most or all of a warm season crop’s N needs. Cool season crops need additional N – succulent green manures or organic fertilizer. Legume or legume-grass cover crops can provide 35-100 lb available N/ac.31
- 32. Clemson U. recommendations forP exceed crop P removal even where P tests sufficient. Vegetable harvests remove 20 – 60 lb phosphate/ac. Reduce phosphate application to this range except where soil P is below sufficiency. Very high soil P inhibits mycorrhzal fungi – apply less P for net drawdown. Yield Why it Works: some Enhancements to Consider Phosphorus application rate In low-OM, low-biological activity soil, much of applied P is tied up, and rates higher than actual crop uptake are needed for optimum economic yield. In healthy, living soil, mycorrhizae and other soil life make more P crop-available. 32
- 33. A couple concernswith the Clemson recommendations • Micronutrient recommendations based on crop only, without reference to soil test level: – Manganese recommended for snap bean (“Mnsensitive crop”) where soil Mn level is ample. – No Mn is needed in this case. 33
- 34. Four Principles ofSoil Health • • • • Keep soil covered as much of year as possible. Maximize living roots in the soil profile. Minimize soil disturbance. Energize the soil system with biodiversity. – Multi-species cover crops - 5 or more species from 3 or more plant families Based on the work of the NRCS Soil Health Team in Greensboro, NC – David Lamm, Ray Archuleta, Steve Woodruff, and Terry Briscoe 34
- 35. Why it Works:Strengths of the System - maximizing soil coverage, living roots • Tight Rotation – 18 cover and 18 cash crops in 13 years • No unplanted fallow • Living vegetation present most of the year • Cover crops provide abundant root exudates for soil life 35
- 36. Why it Works:Strengths of the System - minimizing soil disturbance • No chemical pesticides, herbicides, fungicides – protects soil life. • Limited use of soluble fertilizer (potassium sulfate only). • Minimal, shallow tillage to plant cover crops after vegetable harvest. Cover crops, cash crops, and even weeds are far better for the soil than herbicide-fallow. 36
- 37. Why it Works:some Enhancements to increase cover & roots, reduce disturbance Pepper starts are no-till transplanted by machine into a roll-crimped cover crop of wheat at North Carolina A&T State University, Greensboro. • Reduce tillage and waiting period after cover crop. • No-till cover crop roll-down and vegetable planting. • Practical for tomato, pepper, broccoli, cabbage, other transplants, potato, garlic, squash, beans. • Possibly cucumber, melon. • Not suitable for beets, carrots, direct-sown greens spading machine for onepass cover crop tilldown. 37
- 38. Practical considerations: greenmanure cover cropping Pros: Readily-available food for soil life Maximizes active organic matter Biofumigation (brassica covers) Fine seedbed for direct-sowing Accelerates nutrient release Cons: Tillage burns up SOM, disrupts soil fungi & earthworms May lead to crusting, erosion Stimulates weed emergence Plow-down vetch green manure feeds soil life, releases N, facilitates seed bed preparation. 38
- 39. Practical considerations: roll-crimping Pros: Maximizes stable and total organic matter. Continuous soil coverage. Reduces emergence of annual weed seedlings. The roller-crimper terminates Soil fungi, earthworms mature annual cover crops undisturbed. like this without tillage or Cons: herbicides. Slower nutrient release. Lower soil temperature. Cannot direct-sow fine seeds. Perennial weeds may increase. 39
- 40. Why it Works:Strengths of the System - energizing with diversity • 20 vegetable crops from 11 plant families. • Cut flowers in rotation add more diversity. • 9 cover crops from 3 plant families. • Each crop fosters a unique soil microbiota in its rhizosphere. Diversified crop rotations support a wider diversity of life below ground, thereby enhancing soil fertility and soil quality. 40
- 41. Why it Works:Enhancements to consider to increase diversity • NRCS soil health teams in Greensboro, NC and in North Dakota are planting cover crop mixes of 5 – 10 species from 3 – 5 families. • Increased benefits to soil quality and cash crop yield are seen compared to grasslegume biculture. Some examples: Rye, oats, hairy vetch, crimson clover, Austrian pea (winter – commercially available) Rye, wheat, oats, tillage radish, Aus. pea, crimson clover, vetch, turnip, mustard (winter – NRCS trials in VA) Sorghum-sudan, pearl millet, cowpea, buckwheat, sunflower (summer – used in home garden) 41
- 42. Building Soil Organically:A Discussion of Practical Applications and Why They Work Bo Holland Screech Owl Farm Nelson County, VA Daniel Parson Oxford College Farm Oxford, GA