Effect of Emerging Soil Chemical Amendments on the Replant Soil Environment and Growth of Malus hupehensis Rehd. Seedlings

The effects of different soil chemical amendments (T1, 1‰ quicklime + 1‰ superphosphate; T2, 1‰ quicklime; T3, 1‰ superphosphate) on the soil environment and growth of Malus hupehensis Rehd. seedlings in aged apple orchard soil were studied to provide new insight into the prevention and control of apple replant disease. The amendments differed in their ability to ameliorate the soil environment; nevertheless, they all promoted the growth of M. hupehensis Rehd. seedlings, and the greatest enhancement of growth was observed in T1. On August 15, 2018, soil urease, sucrase, phosphatase, and catalase activities were 1.67 times, 1.32 times, 1.62 times, and 1.35 times higher in T1 compared with CK, respectively. The soil pH increased, which alleviated soil acidification. T1 also promoted the renewal of the community structure and the diversity of soil microorganisms. The copy numbers of Fusarium solani and Fusarium oxysporum were 71.96 and 70.30% lower in T1 compared with CK, respectively. The seedling height and root length of M. hupehensis Rehd. seedlings increased by 40.97 and 289.69% in T1 compared with CK, respectively. Therefore, soil replanting obstacles can be overcome with the application of quicklime and superphosphate; these soil chemical amendments also improve the soil microbial ecological environment and promote the growth of M. hupehensis Rehd. seedlings.