Organic Compost as a Soil Amendment in a Crop–Livestock Integration System Under Climate Risk: Effects on Microbial Activity and Soil Fertility

Sandy soil conditions and climate risk frequently lead to agricultural production failures in these areas, justifying studies to identify management practices that make the soil more resilient to abiotic stresses. The objective of the study was to evaluate the temporal dynamics of microbial activity and soil fertility attributes under an integrated crop–livestock system subjected to the addition of organic compost and influenced by seasonal climatic variations. Soil sampling was conducted at four sampling periods over three years in an experimental area used for pasture and grain cultivation. Nine attributes related to microbial activity and nine related to soil fertility were assessed. Microbial activity was significantly impacted by the temporal factor. Integrated systems resulted in increased microbial biomass nitrogen and glycosidase activity compared to fallow. Multivariate analysis showed that the season factor accounted for 95% of the accuracy in predicting the observed results, with the microbial component driving the majority of this temporal effect. Under the conditions observed, the compost appears to stabilize soil microbial activity in systems containing U. ruziziensis; however, the results do not support claims of a universal effect on soil quality improvement, nor do they allow for a causal link to be established between this stability and water availability.