Living Soil for a Sustainable Future: Cover Crop Effects on Soil Health and Productivity
Taggart, Samantha P.
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Agricultural land management practices impact the physical, chemical, and biological characteristics of soil, including the structure of the community of microorganisms present in the soil. The community of soil microorganisms, in turn, directly influences processes such as nutrient cycling and water infiltration and retention, which shape the long-term fertility and productivity of an agricultural landscape. The purpose of this study was to examine the effects of cover cropping on the soil biological and chemical features that contribute to soil fertility. The study looked at two summer cover crops – cowpea (Vigna unguiculata) and sorghum-sundangrass (Sorghum xdrummondii) in comparison with no-cover control – and their effects on soil respiration, soil organic matter and nitrogen availability, and lettuce production. Using soil samples taken from the in-field experiment, a parallel laboratory aerobic incubation study was conducted to examine the effects of the cover crop treatments on the transformation of nitrogen over five weeks. Both cover crops significantly increased soil organic matter, total organic carbon, and extractable potassium and magnesium by over 17% compared to the no-cover crop control. Cowpea significantly increased extractable soil nitrate and respiration rate compared to the no-cover control. Cowpea also resulted in the largest lettuce crop production as measured by both fresh weight and leaf area, but not different from the no-cover control. Sorghum-sudangrass decreased extractable soil nitrate concentration as well as lettuce fresh weight and leaf area compared to the control and cowpea. In conclusion, the study found that sorghum-sudangrass and cowpeas both increased soil organic matter, but only cowpea increased extractable inorganic N and lettuce production for sandy loam soils in the Mid-Atlantic and should be considered for these vegetable cropping systems.