Soil fertility and agronomic performance of soybean and maize grown successively with sewage sludge compost applied as a micronutrients source in Cerrado

Abstract

Agricultural crops in the Brazilian Cerrado region soils are becoming deficit of some micronutrients. The supplementation of these elements to soil via fertilizers is extremely necessary. The sewage sludge compost (SSC) contains considerable amounts of organic matter and crop nutrients and could be used as an organic fertilizer. However, minimal research has been conducted to evaluate the potential of SSC as a micronutrient source in Cerrado. The objective of this study was to evaluate the agronomic viability of SSC as a micronutrient source for soybean and maize crops grown successively in Cerrado soil with low natural fertility. Since 2017, an experiment is being carried out under field conditions in Selvíria, MS, Brazil, with soybean as a summer crop and maize as a winter crop. The experimental design is in a randomized complete block design with four replicates. The treatments are being conducted following a factorial scheme [4 x 2 + 2]. In october 2017, four doses of SSC (5.0, 7.5, 10.0 and 12.5 Mg ha-1, wet basis) were applied to plots in total area and in the inter-rows. There are two control plots, i.e. one without any fertilizers or amendment and the other having no SSC addition but with mineral fertilizer application. Soil samples are being collected at the 0-20 and 20-40 cm depth at the end of crop harvest to evaluate the soil fertility (OM, pH, CEC, H + Al, Al, BS, SB, Total-N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Ni, and Zn). In both crops, the agronomic parameters, including yield components, concentrations of macro and micronutrients in plant tissues (nutritional status) and in grains, SPAD index, the capacity of extraction and export of nutrients and grain yield are being measured. The data set will be statistically analyzed using ANOVA, Tukey's test, correlation, and polynomial regressions.