Improving Soils with Summer Cover Crops and Broiler Litter Compost in Fall Organic Vegetable Systems.

Cover crops and composted broiler litter (CBL) are two organic methods used to improve soils and organic vegetable crop production. A study is underway at Crystal Springs, Mississippi testing the influence of four summer cover crops: sunnhemp, sesame, sorghum-sudan grass and a sunnhemp + sesame blend, in combination with four rates of CBL: 0, 1.25, 2.5 and 5.0 tons/acre, on fall vegetable production. The cover crops, in four replicates, were established in early summer 2011, mowed and incorporated into the soil in August. The CBL rates were applied within each subplot and tilled before transplanting broccoli cv. Marathon into raised beds in September. Soil tests were done pre- and post- cover crop, and after the broccoli were harvested.  Soil tests taken after incorporating the cover crops but before applying the CBL did not show any significant differences among cover crop treatments in soil pH, organic matter content, or available nutrients (P, K, Ca, Mg, Zn, or S). After application of CLB and production of a late fall broccoli crop, soil tests indicated that cover crop had minimal influences on soil parameters.  However, increasing CBL rates led to increased residual P and K availability, with modest elevations in soil pH and organic matter.  These changes were not necessarily correlated with broccoli leaf tissue nutrient levels, crop yield or quality.