Organic fertilizer from Compost Barn system improves soil microbiological attributes

Raw database of the first and second years of corn cultivation with the application of different doses of organic fertilizer from the compost barn system. ABSTRACT: The Compost Barn system consists of a collective facility for cattle where manure is incorporated into the substrate, generating an organic fertilizer through in-situ composting. The objective of this study was to evaluate the effects of applying different doses of organic fertilizer from the Compost Barn system on soil microbiological attributes and corn (Zea mays L.) productivity. The study was conducted in a randomized block design (n=4), evaluating organic fertilizer application rates equivalent to 0, 6, 12, 18, 24, and 30 t ha-1 in corn cultivation over two growing seasons. Total organic carbon (TOC), microbial biomass carbon (MBC), microbial quotient (qMIC), soil basal respiration (SBR), metabolic quotient (qCO2), microbial biomass nitrogen (MBN), total nitrogen (TN), and the activities of β-glucosidase (βG) and arylsulfatase (AR) enzymes were evaluated. Additionally, corn grain yield (GY) was determined. Doses were compared with the control using Dunnett's test (P<0.05), followed by the application of regression models, principal component analysis (PCA), and redundancy analysis (RDA). Dunnett's test revealed a significant difference for the application doses when compared to the control, with the highest values of MBN, MBC, qMIC, βG, and AR found with the application of 30 t ha⁻¹. Regression models identified linear increases in MBC (r²=0.93; r²=0.98), qMIC (r²=0.93; r²=0.96), βG (r²=0.87; r²=0.98), and AR (r²=0.95; r²=0.98) across the tested doses, in both evaluated cultivations. GY was positively correlated with MBN (r²=0.40), qMIC (r²=0.43), and MBC (r²=0.45), with a negative effect of qCO2 (r²= -0.37) on this variable. Furthermore, the RDAs revealed that physicochemical and environmental variables also influence microbiological variables. It is concluded that the application of organic fertilizer from the Compost Barn system positively modifies soil microbiological attributes and affects corn grain yield.