Soil Quality in Organic Vegetable Plots with Compost and Tillage Treatments.

Tennessee Technological University established a long term organic research farm in 2007 to determine optimum compost rates for various organic vegetables and fruits.  Initially 144 plots were set up in a randomized block design.  This project addresses ecosystem services derived from soil, including nutrient cycling, carbon/nitrogen sequestration, decomposition, and plant support and nutrition.  These services benefit human kind and are affected by soil management practices, such as compost application and tillage treatments.  Thirty-six of these 1.3m x 7.6m plots are used for this project to study compost rates and tillage affects on soil quality parameters. Measured soil quality parameters include soil carbon and nitrogen, soil respiration, soil bulk density, water infiltration, earthworms, phosphorus, potassium, calcium, magnesium, pH, nitrates, and soluble salts. Tomatoes, beets and bush beans were grown in summer of 2008 and spring and summer of 2009, respectively and yields and crop quality measured.  In the fall, 2008 three tillage treatments (no-till mulched, reduced conventional tillage, and spading machine tillage) were added to the four compost rates (0, 10.7, 32.2, 53.7 Mg/ha) and each treatment triplicated.  Preliminary results without the tillage treatments from summer 2008 indicate that yield was positively correlated with compost rate.  Soil analysis indicated that soluble salts, pH, nitrates, and soil carbon and nitrogen were greater in the highest compost rate.   Results for soil, water and crop quality parameters based on compost rate and tillage treatment will be presented from the long term organic system.