Change in Soil Microbial and Enzyme Activities in Response to the Addition of Rock-Phosphate-Enriched Compost

Abstract

Phosphorus (P) is considered a nonrenewable resource that plays a key role in agriculture and such studies are needed to evaluate alternative sources of this element. In the current study, objectives were to evaluate soil microbial respiration and enzymatic activity resulting from the addition of rock-phosphate-enriched organic compost to soil under incubation conditions. An organic-mineral compost (OMC) was produced by aerobically composting a mixture of coffee grain trash (62%), bovine manure (7%), phosphate rock (28%), and gypsum (3%) for 3 months. Different amounts of OMC were added in a portion (100 g) of soil, and then this mixture was incubated for 28 days. After this time, soil microbial respiration (SMR), biochemical parameters, and available P were evaluated. The addition of OMC led to significant increase in SMR, dehydrogenase, fluorescein diacetate hydrolysis, β-glucosidase, and phosphatase activity, which were dependent on the added amounts of the compost. The values of available P in soil increased significantly (13 times) with the OMC addition when compared to the control.The assay showed that P-enriched OMC application impacted soil function and improved soil biochemical properties. These results suggest that this practice may be of great importance for soil fertilization.