Cover crops and concentrations of carbon and nitrogen in Amazonian soil

Abstract

The present study aimed to evaluate the potential of dry matter production by cover crops and their effects on the dynamics of organic matter, organic carbon and nitrogen in the soil. This study contributes to minimize the effect of climate change and improve agricultural production systems. The experiment was conducted under field conditions, in the experimental area of the Federal Institute of Education, Science and Technology of Rondônia, Colorado do Oeste Campus, in the municipality of Colorado do Oeste, RO, Brazil. The experimental design was completely randomized, arranged in a factorial scheme, with four replications, consisting of six species of cover crops cultivated in pre-season (Crotalária ochroleuca, Crotalária spectabilis, Mucuna pruriens, Cajanus cajan, Canavalia ensiformis and Lablab purpureus) and four sampling depths (0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm). The production and macronutrient contents in the dry mass of shoots of the different cover crops were evaluated, as well as the dynamics of organic matter, organic carbon and N in the soil at different sampling depths. The species Crotalaria ochroleuca and Crotalaria spectabilis showed great potential for dry matter production, while Lablab purpureus bean stands out in the extraction of nutrients such as P, K and Ca at full flowering. Lablab bean and Jack bean as cover crops were the most efficient strategies to promote the increase in the input of OM, C and N forms in the soil. NH4+-N and NO3--N contents were higher in the surface layers of the soil. Management with cover crops promoted gradual accumulation of SOM, which made it possible to influence the maintenance and increase of C and N concentrations in the soil and contributed to minimizing environmental impacts and increasing the quality and sustainability of soils and agricultural production systems