Abstract:

This research evaluated the benefits of green manure for soil quality recovery， compared with traditional clear tillage and chemical herbicide application methods， in a Castanea henryi orchard in the typical red soil hill region of Fujian. A randomized block design was adopted， with each block having an area of 0.3-0.5 ha. The experiment site was cleared of natural weeds， then two grass species （Vulpia myuros， Mode₁； Lolium perenne， Mode₂） and a legume species （Vicia villosa， Mode₃） were trialed as green manure crops， and compared with glyphosate （CK₁） and clear tillage treatments （CK₂）， with three replicates of each. After 2 years， the physical and chemical properties of soils in the three green mature and the two CK treatments in the C. henryi orchard were analyzed. It was found that： 1） Compared with the clear tillage and glyphosate spraying treatments， the contents of alkali-hydrolyzable nitrogen， available phosphorus and available potassium in soils of Mode₁， Mode₂ and Mode₃ green manure crops were significantly increased， and the Mode₁ observe values was the highest， which ware 74.14， 156.87 and 234.76 mg·kg^-1， respectively. The soil porosity of the Mode₂ treatment was the highest， at 56.03%. The sucrase activities in soil of the Mode₁ and Mode₂ were significantly increased， with values of 32.29 and 26.87 U·g^-1， respectively. 2） The dominant bacterial groups shared by soils of all five treatments were Actinobacteria， Proteobacteria， Chloroflexi and Acidobacteria， with relative abundances of 24.9%-28.9%， 20.9%-28.8%， 13.7%-18.6% and 10.8%-12.9%， respectively. The dominant fungal groups shared by the five treated soils were mainly Ascomycetes and Basidiomycetes. 3） Compared with the clear tillage treatment， the Chao1 index and Shannon index of the bacterial community in the three green mature treatments were increased， while the fungal presence was decreased. 4） Compared with clear tillage and glyphosate spraying， the relative abundance of Proteobacteria， Bacteroides and Presence of Firmicutes in the soil of the three green manure treatments was decreased， while presence of bacteria of the phyla Chloroflexi and Planctomycetes was increased. The green manure crops promoted the transformation of the soil bacterial community from fast growth to slow growth. 5） Non-metric multidimensional scaling analysis of bacterial and fungal communities in the five treatments showed that the degree of differentiation of the soil fungal community was higher than that of the bacterial community. 6） Correlation analysis and redundancy analysis showed that the green manure crops increased soil invertase and catalase activities and alkali-hydrolyzable nitrogen content； the glyphosate treatment increased soil carbon：nitrogen ratio， and the clear tillage treatment changed fungi-related dominant groups by reducing soil water content. In summary， short-term green manure plantings in C. henryi orchards improved soil physical and chemical properties and enzyme activities to various degrees. Green manure， clear tillage and glyphosate treatments each resulted in a unique soil fungal community.

Key words: Castanea henryi orchard, artificial sod culture, clean tillage, glyphosate, microbial community, soil physicochemical properties, soil enzyme activity