Características agronômicas do feijão-caupi e bioindicadores de qualidade do solo após aplicação de biochar de resíduos animais

Abstract

Biochar is a soil conditioner from different raw materials that is in evidence in agricultural production. The objective of this work was to evaluate the effect of biochar application of different animal residues on the agronomic characteristics of cowpea and, later, to evaluate the responses of soil quality bioindicators. The project was carried out in a greenhouse in Montes Claros (MG). The experimental design used was in randomized blocks with eight treatments and four replications. The treatments corresponded to three types of biochar (beef, pork and poultry), combined or not with fertilizer, and two control treatments (with the addition of calcium and magnesium oxide and calcium and magnesium oxide + fertilizer). To evaluate the agronomic characteristics of cowpea, the morphological and production parameters of each plant were determined. After the bean harvest, total organic carbon, total nitrogen, microbial carbon, soil basal respiration and β-glucosidase enzyme activity were also determined. The collected data were submitted for analysis of variance and the means were compared by the Skott-Knott test (p<0.05). The application of biochar, combined or not with fertilizer, provided an increase in stem diameter, number of pods per plant, number of grains per pod, stem dry mass and grains. There was no difference among treatments for Cmic, RBS and β-glucosidase enzyme activity, while COT, NT and CL were higher in treatments with biochar application. Evaluating only the treatments with biochar application, the soil that presented the highest TOC content was the one where there was a combined application of bovine biochar + fertilizer; the soils with the highest NT content were those with a combined application or not of poultry biochar + fertilizer and swine biochar + fertilizer. Thus, it can be concluded that biochar associated with conventional fertilization can improve soil quality, and consequently the production parameters of cowpea.