Organic mulches and high residue no-till for collard production in Alabama
Data collection has begun on an experiment involving the use of high biomass cover crops in conjunction with organic mulches for the production of no-till fall collards at the Plant Breeding Unit at the E.V. Smith Research Station in Shorter, AL. Data were collected on soil moisture status, weed populations, percent ground cover, soil and mulch nutrient contents and crop yields. Drought conditions prevented full stand establishment of the summer cover crops. Collard seedlings were mulched three weeks after transplanting using locally grown organic mulches. The majority of the collard harvest was donated to the East Alabama Food Bank.
The objectives of the experiment are:
1. To evaluate mimosa prunings, S. lespedeza cuttings and wheat straw as organic mulches in a high residue no-till system; and
2. To compare a legume and a non-legume as high-residue summer cover crops for no-till production of collards and the interaction of cover crop and mulch type on assessment parameters.
Mulches and cover crops were evaluated in terms of weed control, percent ground cover, nutrient content, soil moisture status and crop yields.
Termination of the rye cover crop was completed without herbicides using crimp and roll operations on May 4, 2006. An average of 3.78 tons of biomass per acre was obtained. Application of treatments began on May 29 by drilling Ethiopian sesame and Derry forage soybean as summer cover crops. Drought conditions prevented full stand establishment of the summer cover crops, which were terminated on August 8 with Roundup at the rate of 2 quarts per acre. The residue was crimped and rolled successfully on August 14. Collard transplants were set into this residue on August 15 and 16. Dead collard seedlings were replaced by hand transplanting on August 21. Organic mulches were placed on individual plots on September 11 and 12 at the rate of 3 tons per acre. Collards were fertilized at the rate of 120 lbs N per acre in 3 applications. Harvest was on October 23 with an average yield of 10,344 lbs per acre. Collards that were not used as samples were donated to the East Alabama Food Bank with due credit to SARE. Rye was planted as a winter cover crop on November 14.
Mulches were evaluated in terms of weed control, percent ground cover and soil moisture status periodically from May until October. Soil samples from each plot were collected and fractionated by depth for analysis of total C and N, P, K, Ca and Mg before treatments were applied. These observations, in combination with nutrient analyses from harvest residues, will be compared to those at the end of the experiment to determine nutrient budgets over the duration of the experiment.
We will continue to collect data on weed control, percent ground cover, soil moisture status and crop yields during 2007. In addition, we will also begin field decomposition studies using nylon mesh litterbags containing organic mulches and summer cover crops. The residue will be periodically retrieved from the field and analyzed for total C and N, P, K, Ca and Mg to determine mineralization rates of these nutrients under field conditions.
Cover crop treatments will be established around May 7, 2007, after collecting soil moisture, weed population and ground cover data. The summer cover crops will be terminated around July 21, after which weed population, percent ground cover and soil moisture observations will continue. Measurements on these parameters will continue for the duration of 2007 and beyond. Collard seedlings will be no-till transplanted around August 7 and mulch treatments will be applied around August 21. Organic mulch and summer cover crop decomposition and nutrient release studies will begin at this time. Collards will be harvested around October 21, followed by a winter cover crop of rye.
More information about this project can be found at
Impacts and Contributions/Outcomes
A combination of high residue cover crops with in situ organic mulches should provide vegetable growers with multiple benefits, including weed control, improved soil quality and reduced input costs. The selection of collards, as well as summer cover crops, makes this research particularly relevant to growers concerned with reduced-input agricultural systems in the Southeastern region.
Auburn University National Soil Dynamics Lab
411 S. Donahue Drive
Auburn, AL 36849
Office Phone: 3348444666
Auburn University Dept. of Horticulture
101 Funchess Hall
Auburn, AL 36849-5412
Office Phone: 3348443050
Auburn University Dept. of Agronomy and Soils
202 Funchess Hall
Auburn, AL 36849-5412
Office Phone: 3348443963