Changes in Soil Status during Third Year of Summer Cover Crops.

Cover crops can increase soil organic matter, structure, and nutrient availability. In three years of trials from 2011 through 2013, we tested four crop or crop blends as summer cover crops prior to transplanting fall vegetables. Crops tested included sorghum-sudan (Sorghum bicolor x S. bicolor var. sudanese), sunnhemp (Crotalaria juncea), sesame (Sesamum indicum), sunnhemp + sesame. Cover crop and composted broiler chicken (Gallus gallus) litter (CBL) treatments were repeated in the same plots in each of the three seasons. The fall vegetable crop was broccoli (Brassica oleracea, var. italica) in 2011 and 2012, and lettuce (Lactuca sativa) in 2013. Soil organic matter, pH and nutrient tests were made prior to seeding and after incorporation of cover crops, and after the subsequent vegetable crops each year. Prior to the 2013 application of CBL but after incorporation of the summer cover crops, soil testing indicated significant increases in extractable phosphorus and zinc from CBL applications in previous years. There was also significantly more organic matter and extractable sulfur in soils from the sunnhemp plots than in soils from other cover crop treatments. After the fall lettuce crop in 2013, soil testing indicated that increasing CBL rate resulted in higher P, K Zn and Na soil test levels, but no differences in these or other parameters tested due to cover crop treatments. Neither cover crop nor CBL treatment appeared to have a significant influence on the changes in organic matter, pH or extractable nutrient levels from prior to planting the lettuce until after harvest.