Increasing Agricultural Soil Health Through Crop Diversity

Human activities, including agricultural production, promote global climate warming by increasing atmospheric carbon dioxide (CO2) concentrations. Soil disturbances release stored soil carbon (C) as CO2 alongside depleting soil organic matter and soil nitrogen (N) reserves. Soil microbes (microscopic bacteria and fungi) regulate C and N cycling, therefore agricultural systems depend on healthy microbial communities that provide resilience to climate change through C and N storage. Due to the diverse relationships different plants have with different soil microbes, scientists propose increasing crop diversity to increase and diversify soil microbe communities. Through long-term research at the Whittaker Environmental Research Station (WERS), we are analyzing both the above- and below-ground effects of crop diversity. We expect that diverse crop communities will cultivate larger and healthier soil microbe populations than less diverse plots. To assess soil microbe communities, we quantify C and N in microbial biomass. Soil microbes are lysed by chloroform- fumigation, and microbial C and N is determined by difference from non-fumigated soil. Samples undergo a base-catalyzed free radical oxidation to oxidize C to CO2 and N to NO3-, which are then detected through gas analysis and colorimetric determination. By determining the effects of plant diversity on soil microbial communities in monocultures and polycultures of five common crops, crop management recommendations can be made to increase overall soil health and combat climate change