Impacts of Cover Crops on Soil Health and Soil Microbial Ecology.

Soil management associated with sustainable intensification, such as cover cropping, can help maintain soil quality, enhance crop productivity, and minimize the negative effects of agricultural production on the environment. In the past, soil quality assessment focused on soil’s physical and chemical properties, but several recent studies have emphasized soil biology as an important indicator of soil quality. Soil quality enhances soil biological activity, which affects key soil properties such as soil structure, soil organic matter and nutrient cycling. The objective of this study was to assess the effects of different cover crops on soil health and soil microbial ecology using selected biological indicators. Soil samples ( 0-5 cm and 5-15 cm ) were taken in May 2014 from Ashland Bottoms, Kansas, prior to planting of sorghum from treatments of chemical fallow, double-crop soybean, summer non-legume (sorghum-sudan grass), summer legume (late-maturing soybeans), winter non-legume (tillage radish) and winter legume (crimson clover) that received 0 and 80 kg N ha^–1, applied as urea-ammonium nitrate. Experimental design was a split plot in randomized complete block design .Key indicators analyzed included dissolved organic carbon , microbial biomass carbon and nitrogen, potentially mineraliazable nitrogen  and soil microbial respiration. Summer non-legume and winter non-legume had significantly higher rate of microbial respiration in the upper 0-5 cm layer compared to chemical fallow. Double-crop soybean, winter non-legume, summer legume and summer non-legume also had increased microbial biomass nitrogen in the 0-5 cm layer compared to chemical fallow. Preliminary results show that double-crop soybean, winter non-legume, summer non-legume and summer legume can potentially improve soil fertility by adding nitrogen from microbial sources within the top 0-5 cm depth. However, by contributing to an increased microbial biomass nitrogen as well as encouraging soil respiration, summer non-legume can be said to be the most effective cover cropping regime to enhance soil health.