With a recent increase in collective knowledge about harmful environmental impacts of agricultural processes, much research in agriculture now focuses on more sustainable practices. Two such practices are the use of cover crops and microorganism stimulants. Both contribute to building healthier soil, which can be beneficial in the long term to both the personal profitability of the farmer and quality of the land. The purpose of this study was to determine the effects of a commercially available microorganism stimulant called AgZyme and a mix of cover crops (annual rye grass, bayou kale, enrich radish and crimson clover) on soil physical, chemical and biological characteristics, as well as corn yield and profit in a strip-tilled cornfield in Northfield, Minnesota, USA. Soil core samples were taken three times throughout the growing season of 2015. Variation in naturally occurring soil types was also considered. Specific soil variables measured included ammonia, nitrates, orthophosphates, percent organic matter, percent moisture, bulk density, CO2 respiration, microbial and fungal biomass and diversity, and abundance and expression of microbial genes related to soil and crop health.
Results/Conclusions
Soil nutrient analyses showed a significant decrease in ammonia levels over the growing season. Nitrates and phosphates significantly increased over the growing season. Nutrient levels did not significantly vary with addition of AgZyme or a cover crop. Soil microbial biomass and CO2 respiration were higher in the Agzyme treated soil, suggesting an increase in microorganism presence and better nutrient mobilization. The C:N ratio was lower in Agzyme treated soil, indicating more nitrogen is available for plant use. In the cover crop area annual rye grass grew at high density followed by low densities of the other three species. When soil types were compared well-drained Blooming silt loam had better overall soil health based on soil biomass and C:N ratios. Yields ranged from 477 to 495 bushels per hectare and were not significantly different among the Agzyme, cover crop and control treatments. Profits were higher in the control treatment ($866/ha), followed by the Agzyme ($794/ha) and cover crop ($548/ha) treatments. While profits decreased slightly with use of a microorganism stimulant and more with the cost of planting a cover crop, benefits in terms of soil health and continued high yield are likely in the long term.