Effects of planted grasses on soil enzyme activities and microbial communities in a kiwifruit orchard

In order to explore and select suitable grass varieties for kiwifruit orchards in the Northern Qinling Mountains, Dactylis glomerata, Lolium perenne, Trifolium repens, and a grass combination were planted inter-row in a kiwifruit orchard, while clean tillage was applied as a control. The effects of different grasses on the soil enzyme activities and soil microbial communities were investigated. Results showed that, unlike sucrase activity, catalase, urease, and phosphatase activities significantly decreased with increasing soil depth (P < 0.01). Compared with clean tillage, planting grasses could improve catalase, urease, sucrase, and phosphatase activities in the 0 – 20 cm and 20 – 40 cm depths of the kiwifruit orchard soil. However, the effect was either significant or non-significant depending on the grass variety. Bacteria were the dominant flora, accounting for 99.74%～99.94% of the total soil microorganisms. The amount of bacteria, fungi, and actinomycetes was influenced by the various grass varieties in the 0 – 20 cm and 20 – 40 cm soil depths. In particular, with the exception of T. repens, the total amount of microbes was higher in the 0 – 20 cm fraction of planted soils than in that of clean-till soils. However, with increasing soil depth the total number of microbial species decreased in soil planted with grasses, while increasing in clean-till soils. In conclusion, this study showed that planting grasses could improve the soil enzyme activities and amount of soil microbes in kiwifruit orchards. In particular, we especially recommend the woodland combination of D. glomerata, L. perenne, and T. repens due to their higher aboveground biomass. This study could provide the theoretical basis for the promotion of a ‘forest-grass-sheep ecological cultivation and rearing cyclic model in northern China’.