Seasonal responses of soil microbial biomass C and enzymatic activity comparing no-tillage and integrated crop-livestock systems

Abstract

Sustainable agricultural systems, such as integrated crop-livestock (ICL) and no-tillage (NT), aim to sustainably produce crops and livestock while simultaneously conserving soil and its microbial properties, mainly in tropical regions. However, little is known about how microbial properties respond seasonally to management applied in NT and ICL. Thus, this study assessed the seasonal responses of soil microbial biomass C and enzymatic activity comparing both NT and ICL. The experimental area, under a block design with four replicates, with both NT and ICL management, was implemented in December 2022 on Yellow Argisol soil in Maranhao state, Brazil. Soil samples were collected (0–20 cm depth) in March, June, September, December, and March (2023). The results showed an effect size varying between 0.06 and 0.95 for agricultural systems, and 0.63 to 0.95 for sampling time. For the interaction between agricultural systems and sampling time, the effect size was superior to 0.86. NT showed initially higher microbial biomass C (∼50 %), leveling with ICL by the end of the sampling period. Phosphatase and dehydrogenase increased in ICL from March to June (∼200 % and ∼700 % for phosphatase and dehydrogenase, respectively), while fluorescein diacetate hydrolysis fluctuated in NT. Urease was higher (∼100 %) during all sampling times in NT. Linear discriminant analysis revealed distinct responses across sampling times, with a positive effect of pH on enzymatic activity in both systems and soil moisture and P impacting positively on microbial biomass in ICL. Our results revealed significant seasonal responses of soil microbial biomass and enzymatic activity comparing NT and ICL, but with distinct responses to agricultural systems. The study showed seasonal variation of soil microbial biomass and enzymatic activity dependent on the characteristics of NT and ICL. Therefore, understanding these differences helps farmers make better decisions for healthier soil and better crops.