Impact of winter coverage crops and nitrogen fertilization on soil respiration and nitrogen mineralization in no-tillage systems

Microbiological activity in soil is crucially important to maintaining soil quality. Soil is sensitive to management practices, and microbiological activity plays a crucial role in processes like transforming organic N into inorganic fractions. The objective of this study was to assess how winter coverage crop residues influence soil respiratory activity and N mineralization during successive corn crop developments under a no-tillage regime. We employed a randomized block experimental design with subdivided plots and three replications. The main plots comprised various coverage crops (Black Oats, Ryegrass, Rye, White Lupin, Common vetch, Turnip, consortia of Oats + Vetch and Oats + Vetch + Turnip, while subplots received doses of N-mineral (0 and 180 kg ha-1) during the corn growth stage. We evaluated the respiratory activity of microorganisms and levels of inorganic N in the soil throughout the corn crop cycle. The consortia of coverage crops exhibited distinct responses in respiratory rates, with Oats + Vetch having superior results compared to Oats + Vetch + Turnip. We observed positive responses in nitric N (N-NO3-) due to the mineralization of common vetch residues within the first fifteen Days After Sowing (DAS). However, N-mineral doses from nitrogen fertilization during the corn coverage age phase did not alter the respiratory of the microorganisms nor did it alter the concentrations of N-NH4+ in the soil. Mineral fertilization resulted in the immediate availability of N in the form of N-NO3-.