Woodleaf Farm Soil Management System Table 1

Organic Agriculture May 02, 2016 Print Friendly and PDF

This article is part of the Woodleaf Farm Organic Systems Description.

Table 1. Woodleaf Farm Soil Management System

Strategies and tools

Implementation details

I. Soil organic matter building1 See also Living Mulch and Organic Residues.
Optimize quantity of soil organic matter (SOM) SOM increased from an average of 2.2% in the 1980s to an average of 5.1% in 2014 (Fig. 1).
Optimize quality of soil organic matter Diverse organic residues are added regularly. Materials typically are high in carbon and low in nitrogen. 
Maintain soil cover* Since the 1990s, a perennial grass/legume/weed living mulch has been grown between and beneath tree and vegetable crop rows.
Use winter cover crops Winter cover is maintained by the year-round perennial living mulch between crop rows. Total acreage in winter cover crops ranges from 30 to 50%.
Use summer cover crops Summer cover is maintained by the year-round perennial living mulch between crop rows. Total acreage in summer cover crops ranges from 30 to 50%. 
Apply organic soil amendments and residues  Residues include mowed living mulch, chipped branch wood, and yard waste compost. Materials are surface applied annually.
Apply chipped branch wood Trees are pruned twice per year. Branches are chipped with a mower, and chipped wood is left in row middles and blown beneath trees. 
Apply manure-based compost Manure-based compost was applied through 1991. Woodleaf no longer uses manure-based materials.
Apply plant-based compost Woodleaf applies yard waste compost one to three times per year at a rate of 2 tons/acre.
Apply a mix of carbon:nitrogen ratio organic amendments Organic residues with different C:N ratios are added spring, summer, and fall. 
Reduce tillage Woodleaf has practiced no-till/reduced tillage since the 1990s. 
Diversify soil biota with crop and noncrop diversity* Woodleaf grows both perennial and annual crops. The living mulch contains diverse annual and perennial species with different rooting types and depths.
Grow a living root in the soil year-round* The perennial living mulch maintains year-round presence of grass, legume, and weed roots. 
Mow weeds to enhance nutrient cycling Weeds are a major component of the perennial living mulch, which is mowed two to six times per year.
Till weeds to enhance nutrient cycling Since the 1990s, Woodleaf has used no-till and reduced-tillage methods. Weeds are no longer incorporated.
Apply organic nonliving mulches such as straw Alfalfa hay is used over the winter in no-till trellis vegetable crop rows.
Maintain animals/livestock as part of the cropping system Chickens were part of the system in the early 1990s, but have not been present since 1994.
II. Soil fertility building Table 2 shows Woodleaf's soil health trends, targets, and amendments. 
Match nitrogen supply to crop need The diverse mix of organic residues and amendments supplies N gradually from the soil reservoir. On average, total soil N levels are high (3,204 ppm) (Fig. 4). Nitrate-N decreased from an average of 23 to 9 ppm between 1982 and 2014 (Fig. 3).
Optimize soil potassium levels Between 1982 and 2014, average soil K increased from 127 to 173 ppm (Fig. 16).
Optimize soil phosphorus levels Between 1982 and 2014, average soil P increased from 46 to 95 ppm (Fig. 17).
Optimize soil calcium levels Between 1982 and 2014, average soil Ca increased from 1,202 to 1,524 ppm (Fig. 13).
Optimize soil magnesium levels Between 1982 and 2014, soil Mg increased from an average of 229 to 240 ppm (Fig. 18).
Optimize soil micronutrient levels Between 1982 and 2014, soil zinc and copper increased (Fig. 5 and Fig. 6). Boron, sulfur, and manganese decreased (Fig. 7, Fig. 8, and Fig. 9).
Optimize soil Cation Exchange Capacity (CEC) Between 1982 and 2014, average CEC increased from  9.5 to 11.7 meq/100g (Fig. 2).
Optimize soil cation balance Woodleaf's target is 68-70% Ca, 15% Mg, and 3–7% K. The current average across fields is 67% Ca, 18% Mg, and 5% K (Fig. 14, Fig. 15, and Fig. 19).
Optimize soil pH Between 1982 and 2014, soil pH decreased from an average of 6.7 to 6.4 (Fig. 20).
Apply off-farm soil amendments and fertilizers Minerals, gypsum, and yard waste compost are applied annually.  Gypsum is applied each spring at 250 lb/acre. Boron is applied annually at 10 lb/acre.
Apply foliar minerals and fertilizers Kelp, sulfur, boron, and other minerals are sprayed in a foliar mineral mix one to three times at bloom, depending on precipitation during bloom.
Apply foliar compost teas Carl Rosato experimented with compost teas in the early 1990s, but stopped using them in the mid-1990s based on on-farm testing (Disease Fig.1 and Disease Fig. 2)
Rotate crops Rotation is weak. Peaches are more than 50% of total acreage and often are replanted in the same field. No replant disease has been observed, so Carl sees no need to change rotation practices.
Use soil tests to measure soil trends Carl usually samples soil for analysis every 1 to 5 years in each of seven fields.
Optimize irrigation to minimize evapotranspiration (ET) loss** Woodleaf uses microsprinklers. Tree tops receive 2 to 2.5 inches of water per week, while vegetables receive 1 inch/week.
1*Strategy listed in the NRCS Soil Quality Initiative
**ET can be determined with the use of
CIMIS data, in-field soil moisture measurement, or both.

This table is part of the Woodleaf Farm Organic Systems Description.

Table of Contents:

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.