Development of a More Sustainable Sweetpotato Production System in Alabama
Type of DegreeThesis
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Field experiments were conducted from 2003-2005 to evaluate the influence of grass and legume cover crops, no-tillage, and varying rates of nitrogen on commercial sweetpotato production. Cover crops used for the no-till operation were crimson clover, hairy vetch, winter rye, and winter wheat, along with a bareground treatment, which was conventionally planted. Applied nitrogen rates were 50 kg•ha-1 or 100 kg•ha-1. The experimental design was a randomized complete block design. Each experimental unit consisted of one of the four cover crops at one of the two nitrogen rates. These eight treatments were compared to two bareground treatments at one of the two nitrogen rates. Each treatment was planted with ‘Beauregard’ sweetpotato. Biomass samples were taken from the cover crops for biomass, carbon, and nitrogen analysis. Cone index measurements were taken after transplanting to determine soil compaction for each treatment. Soil temperature and percent soil moisture were taken for each treatment throughout the growing season. Soil samples were taken to determine organic matter content pre and post treatment. When the sweetpotatoes were harvested, yield data was taken from each treatment. All of the cover crops produced significant quantities of biomass compared to the bareground treatment. Hairy vetch and crimson clover produced desirable C:N ratios. Cone index measurements were reduced in 2005 compared to 2004. Rye, crimson clover, and wheat cover crops conserved soil moisture. There was an increase in organic matter from 2003 to 2005. Highest yields of sweetpotato were obtained when no-tilled into crimson clover or hairy vetch cover crops. Highest yields of sweetpotato was also obtained when either 50 kg•ha-1 or 100 kg•ha-1 of nitrogen was applied. Using crimson clover or hairy vetch cover crops with 50 kg•ha-1 of applied nitrogen yielded higher net returns compared to the conventional bareground method with 100 kg•ha-1.