Abstract:

The 5-year-old‘Yanfu 10’apple（Malus × domestica）trees were differently mulched with black nonwovens and herb residue. The effects of different mulching materials on soil nutrients，soil enzyme activities，and microbial communities in the apple orchard were studied. The results showed that the soil temperature changed under the two different mulching treatments. The soil moisture contents increased during the early stage of fruit tree development under mulching treatments. The soil nutrient contents and the activities of catalase，urease，and sucrase were also elevated by the mulching treatments， especially by the herb residue mulching，comparing with the control. Under the herb residue mulching，the organic matters contents increased by 27.7%，32.1%，and 34.3%，available phosphorus increased by 19.6%，53.8%，and 81.9%，and available potassium increased by 19.1%，35.0%，and 167.4% at different stages of fruit development，respectively. 16S rRNA sequencing of soil bacteria showed that both the black nonwovens mulching and the herb residue mulching increased the α diversity of soil bacteria，especially for the herb residue mulching. Moreover，the β diversity of soil bacteria was more similar under the two kinds of mulch，which was obviously different from the control. In terms of bacterial community distribution，the community abundance of Actinobacteriota，Bacteroidota，and Firmicutes increased by 44.7%，65.7% and 79.7% under black nonwovens mulching，respectively. The community abundance of Proteobacteria and Bacteroidota increased by 15.5% and 54.5% under herb residue mulching，respectively. In conclusion，the herb residue mulching can significantly improve soil moisture contents and soil temperature，increase soil nutrient contents，and enhance soil bacterial community diversity，which is more favorable to the growth and development of apple fruit tree roots.

Key words: apple, mulching in the apple orchard, soil nutrient, soil bacteria, 16S rRNA sequencing