First Year Cover Crops In Mississippi Increased Soil Organic Matter In Conventionally Managed Sweetpotato, but Had No Effect On Yield

Three field trials were established in the fall of 2009 to investigate the long term effects of various winter cover crops on soil attributes and sweet potato production in North Mississippi. In field 1, ryegrass, wheat, crimson clover, hairy vetch, two radishes, mustard, and rape as winter cover crops are being compared with conventional weedy fallow. In the first year, legume biomass was higher than Brassicas and fallow, and Brassicas, except Daikon radish, were not different from fallow. Incorporation of legumes did not increase soil nitrate or organic matter compared to fallow. This may have been due to soybean residue and no-till management of this field for several years. US1 and marketable yield ranged between 152 and 231bu/ac, and 258 and 379bu/ac, respectively, but there were no differences among treatments. The field in location 2 was conventionally managed and planted to sweetpotato for 2 years. Radish and rape were compared to conventional fallow. Soil organic matter increased to 1.3% with radish in comparison to 1.08% for the fallow treatment.  Similar to location 1, yields were the same among treatments with US1 yield ranging from 368bu/ac to 413bu/ac. The field in location 3 has been organically managed for 4 years and treatments were mustard, radish, rape, crimson clover and fallow. Biomass of crimson clover and rape were higher than mustard and fallow, but soil organic matter was the same among treatments. US1 and marketable yield ranged between 157 and 317bu/ac, and 321 and 553bu/ac, respectively but were not different among treatments. In conclusion, first year incorporation of winter cover crops increased organic matter in a conventionally managed field, but there was little or no effect on sweet potato yield.