Integrated multivariate analysis of selected soil microbial properties and their relationships with mineral fertilization management in a conservation agriculture system

Abstract

The effect of mineral fertilizer application on soil microbial community was investigated in a conservation agriculture system. The aim of this work was to evaluate how mineral fertilization with nitrogen (N), phosphorus (P), sulfur (S), and micronutrients (M) affects microbial community structure and function. A 10-year experiment, conducted on a typic Hapludoll using six mineral fertilizer treatments (control, CK; PS; NS; NP; NPS; and NPSM) was evaluated in central Argentina. Microbial community structure and function were characterized by phospholipid fatty acids and community-level physiological profiles, respectively. Soil microbial metabolic activity was determined by monitoring microbial respiration, fluorescein diacetate activity (FDA), dehydrogenase activity and phosphatase activity (PHA). NPS and NPSM treatments showed higher total microbial biomass and gram-positive and gram-negative bacteria, but lower fungal biomass than the remaining treatments. Fertilizer treatments without S (CK and NP) showed lower carbon source utilization and Shannon index than the other treatments. In addition, both FDA and PHA significantly increased under NPSM. An integrated PC analysis indicated that sensitive bioindicators were significantly associated with three carbon sources, one metabolic parameter, and six fatty acid bioindicators. These results provide information about the importance of balanced fertilization with P, N, S, and M in promoting microbial biomass, metabolic activity, and functional diversity.