Cover Crops and Tillage Systems: Three Years of Impacts on Soil Characteristics and Sweetpotato Yield in North Mississippi

Sweetpotato is a high value, high input crop, with an estimated production value of over 500 million dollars in 2012 (USDA, National Agricultural Statistics Service).  Sweetpotato fields are generally left bare after mechanical harvest, allowing for soil erosion.   In 2009, studies of cover crops and conservational tillage systems were begun at Mississippi State University’s Pontotoc Branch Experiment Station (Pontotoc, MS).  Each cover crop species was planted individually in 2010, while some species were mixed for 2011 and 2012 based on 2010 data.  Due to poor plant stand in the no-till planting, yield was very low in 2010.  Total marketable yield ranged from 99 to 133 bu/acre for crimson clover and wheat, respectively.  Changes in soil characteristics were not observed in 2010, possibly due to previous long term no-till soybean and corn rotations. In 2011, modifications including a sub-soiling shank were made to a mechanical transplanter to facilitate planting into the stale bed and stand was improved significantly. Nitrate nitrogen ranged from 27 to 128 ppm for fallow and crimson clover treatments, respectively.  Total sweetpotato marketable yield for stale bed planting on hairy vetch and wheat ranged from 308 to 553 bu/acre, respectively. In 2012, soil organic matter tended to be higher with the stale seedbed when cover crops were compared with their conventional tillage counterparts.  There were no differences in total marketable yield in 2012 when compared to the conventional tillage plots. In 2011 and 2012, sweetpotato yields were comparable between stale beds and conventional tillage. Therefore, with modifications to currently used machinery, stale bed production in connection with winter cover crops can have positive impact on sweetpotato production by reducing erosion and allowing earlier planting.