Impacto do biochar de café sobre as atividades enzimáticas e biomassa microbiana em neossolo cultivados com milho e feijão

Abstract

The application of biochar in bean production has been used to enhance the production of this crop. In the Northeast, maize is one of the most important agricultural products, as it participates in the formation of the income of the farmers and contributes in the feeding of the animals. The use of biochar can bring benefits to the soil and the environment, such as long-term carbon sequestration minimizing the effects of climatic changes, as also presenting a higher yield for the crop. The objective of this study is to observe the effects of the two different types of biochar produced with coffee residues, in different doses, on initial bean and maize growth and the impact on chemical attributes, such as microbial biomass carbon, absolute and enzymatic activities in a Regolithic Neosol cultivated with beans and maize. The experimental design was completely randomized, in a 2x4+1 factorial scheme, being two types of waste coffee grounds (CG), and coffee husks (CH), and 4 doses of each and one control. Being BM= dose 0, and MCG4, MCG8, MCG12 and MCG16 = biochar of coffee grounds, in the doses of 4, 8, 12 and 16, Mg ha-1, respectively; MCH4, MCH8, MCH12 and MCH16 = coffee husks in the doses of 4, 8, 12 and 16 Mg ha-1. All treatments received organic fertilization, bovine manure. At 45 days after sowing, height, diameter, shoot dry matter, soil chemistry, total organic carbon (SOC), microbial biomass carbon (MBC), and absolute and specific enzymes were verified. Most of the evaluated parameters had a positive influence when adding the biochar to the soil at the higher concentrations of MCG12, MCG16, MCH12 and MCH16 doses. When analyzing the MBC, the treatments MCG16 and MCH12 obtained a significant increase of 100.01 and 116.28%, respectively, when compared to the control (CM). It is noticed that the soil that received MCG8, cultivated with maize, stood out considerably in relation to phosphatase with an increase of 216.86% in relation to the control (CM). The enzymes specific for both the carbon of the microbial biomass and the total organic carbon presented responses to the coffee residue. The biochar produced from coffee residues increased in general the chemical, physical, microbial and biochemical attributes of sandy soil cultivated with beans and maize. It is recommended the use of residues from the coffee industry for the production of biochar and application in the bean and maize crop in doses from 16 Mg ha-1.