Sod cultivation significantly enhances soil nutrient availability in a subtropical newly established orchard

Abstract

Sod cultivation plays an important role in managing fruit-tree orchards, which could significantly influence the soil nutrient availability, microbial biomass and community. Yet, how the different functional sod species affect these above traits of orchard is still largely unclear. Here, we employed a field-based study to investigate the effects of two functional sod cultivation on seasonal dynamics of soil nutrient and microbial biomass in a subtropical newly established guava (Psidium guajave) orchard, Guangdong Province, southern China. In this study, four treatments were established: clean tillage (CT), Paspalun natatu monoculture (P), Stybsanthes guianensis monoculture (S) and interplanting with P. natatu and S. guianensis (P & S). Our results showed that season significantly affected NO3--N concentration, net N mineralization (Nmin) and nitrification (Nnit), microbial biomass carbon (MBC) and nitrogen (MBN), dissolved organic C (DOC) and N (DON), as well as soil acid phosphatase (ACP) in two soil layers. However, sod cultivation enhanced NH4+-N and NO3-N concentrations, Nmin and Nnit to some extent, and the increasing magnitude varied with the sod species. Sod cultivation also facilitated soil MBC and MBN, DOC and DON. Moreover, both P. natatu and S. guianensis monoculture and their inter-planting dramatically increased ACP activity, while decreased AP concentration in wet season, suggesting that sod competed for AP with fruit-tree in growing season of a newly established orchard. However, compared with P. natatu, perennial leguminous species S. guianensis had little advantageous effects on soil available N supplement for a short-time investigation in this orchard. We recommend that sod cultivation would be an effective method for enhancing soil nutrient status and reducing chemical fertilization in the orchard. Given that, large-scale and long-term studies are still necessary to investigate the effects and underlying mechanisms of different sod cultivation practices on the soil nutrient availability within various orchards in subtropical China.