Responses of soil microbial community structure and enzymatic activities to long-term application of mineral fertilizer and beef manure

The intensive use of mineral fertilizers to achieve high crop yield has led to soil degradation and poor soil health. Thus, manure application as an alternative to mineral fertilizers can be an effective fertilization strategy to sustain soil health and biodiversity. This study aims to assess the impacts of long-term manure and mineral fertilizers on key soil biochemical and biological indicators. The study was conducted on a 16-year long-term experimental site with six different manure and fertilizer treatments that included no amendments (CK), recommended mineral fertilizer (MF), higher rate of mineral fertilizer (HF), manure application based on the phosphorus requirement (LM), manure application based on the nitrogen requirement (MM), and double the rate of MM treatment (HM). Data showed that higher rates of organic manure application (HM) significantly increased enzyme activities, and soil microbial community phospholipid fatty acid biomass compared to the CK for 0-10 cm soil depth. However, both mineral fertilizer rates did not show any differences in microbial community when compared with the CK for either depth. Soil bacterial community structure was significantly altered by manure and mineral fertilizer application. In comparison to HF and CK, the HM application stimulated some microbial groups (Chitinophagaceae, Burkholderiaceae, Beijerinckiaceae, and Cellulomonadaceae) those are often involved in phosphorus solubilization, nitrogen mineralization, methane degradation, and degradation of complex organic compounds. This study demonstrated that, compared to mineral fertilizers application, the long-term manure application strategy based on different nutrients requirement especially higher manure treatment can be beneficial in enhancing soil biochemical and biological indicators.