Immediate and Residual Effects of Mineral and Organomineral Nitrogen Sources Associated with Concentrated Vinasse on Maize

Owing to the great availability of N sources for agriculture, its complexity in the system, and the demand for new organic sources of nutrients, especially NPK, this study aimed to evaluate the immediate and residual effects of mineral and organomineral sources of N, in combination with different doses of K from concentrated vinasse (CnV), on the performance of the corn crop and the soil electrical conductivity (EC). The study was carried out in an air-conditioned greenhouse, in pots filled with Oxisol. The treatments were four N sources, comprising mineral ammonium sulfate, organomineral ammonium sulfate, mineral urea, and organomineral urea, in combination with four doses of K (K2O), applied in the form of CnV, at doses of 0, 100, 200, and 300 mg kg(-1). Three vegetative cycles were conducted, so the immediate effects were assessed in the first cycle and the residual effects in the second and third cycles. The organomineral ammonium sulfate source promoted the best performance in the maize crop, while K doses were 300 and 200 mg kg(-1), and interactions between these factors were more significant than their single effects. EC increased in the surface soil with the application of K; the highest peaks were observed in the first cycle of maize cultivation and the initial values were not reestablished for the remainder of the study. There were large increases in EC mainly in the first cycle, however only in the most superficial layer of the soil (immediate residual). The values decreased with each cycle, but there was no reestablishment of the initial levels, even 340 days after the last CnV application; the performance of maize was higher with the increased residual doses of K and sources of N, when compared to the immediate effect; the N source that was most beneficial to the corn crop was organomineral ammonium sulfate, in combination with the highest K doses from CnV; the combination of CnV and N sources helped to improve the performance of N mineral and organomineral fertilizers.