绿肥替代不同比例化肥对红壤稻田土壤真菌群落的影响

Replacement of chemical fertilizer with green manure at different proportions affects fungal community in the paddy field of Ultisol

摘要:

【目的】探究绿肥替代化肥的最佳比例及对红壤稻田土壤真菌群落的影响，以期实现我国南方红壤科学培肥和可持续利用。【方法】研究设置7个处理：不施肥(Control)、早稻不施化肥仅翻压紫云英(G)、早稻常规施用化肥(NPK100)、早稻翻压紫云英且常规施用化肥(NPK100+G)、早稻翻压紫云英且化肥减量20%(NPK80+G)、早稻翻压紫云英且化肥减量40%(NPK60+G)、早稻翻压紫云英且化肥减量60%(NPK40+G)。除Control外，所有处理晚稻均常规施用化肥。在晚稻成熟期采集不同处理水稻根表土样品测定土壤理化性质，同时基于Illumina Miseq高通量测序平台对土壤样品在DNA水平上进行测序，分析土壤真菌群落特征。【结果】与常规施用化肥相比，绿肥替代部分化肥处理提高水稻稻谷和秸秆产量。不同农业措施显著改变土壤真菌群落组成(P=0.001)。绿肥替代中低量化肥处理提高土壤腐生真菌的相对丰度，增加土壤有机质的转化效率和养分周转速率。相比于常规施用化肥，绿肥替代0、20%和40%化肥处理土壤腐生真菌相对丰度分别提高33.55%、167.27%和55.28%。此外，绿肥替代中低量化肥处理降低土壤中潜在植物病原菌的相对丰度和多样性。【结论】绿肥替代20%−40%化肥既能提高水稻产量，又能减少农业面源污染、提高土壤养分含量及优化土壤真菌群落。本研究系统评估绿肥部分替代化肥对红壤稻田生态系统的影响，研究结果为我国南方红壤区农业可持续发展提供了理论基础。

Abstract:

[Objective] This study investigated the optimal proportion of green manure replacing chemical fertilizer and its effect on soil fungal community in the paddy field of Ultisol, aiming to achieve soil fertilization and sustainable utilization of Ultisol in southern China. [Methods] This study set seven treatments: no fertilizer (Control), application of Chinese milk vetch without chemical fertilizer in early season rice (G), conventional application of chemical fertilizer in early season rice (NPK100), application of Chinese milk vetch and conventional chemical fertilizer in early season rice (NPK100+G), application of Chinese milk vetch and 80% conventional chemical fertilizer in early season rice (NPK80+G), application of Chinese milk vetch and 60% conventional chemical fertilizer in early season rice (NPK60+G), and application of Chinese milk vetch and 40% conventional chemical fertilizer in early season rice (NPK40+G). The conventional chemical fertilizer was applied in late season rice for other treatments except the Control. The root surface soil samples of different treatments were collected at the maturity stage of late rice for the measurement of soil properties. At the same time, high-throughput sequencing (Illumina MiSeq) was employed to analyze the features of soil fungal community. [Results] Compared with NPK100, the treatments of green manure replacing chemical fertilizer increased the yields of rice and straw. Different treatments significantly altered the soil fungal community composition (P=0.001). Replacing medium and low amounts of chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil, which increased the conversion rate of soil organic matter and nutrient turnover rate. Compared with NPK100, replacing 0, 20%, and 40% chemical fertilizer with green manure increased the relative abundance of saprophytic fungi in soil by 33.55%, 167.27%, and 55.28%, respectively. In addition, replacing medium and low amounts of chemical fertilizer with green manure decreased the relative abundance and diversity of potential plant pathogens in soil. [Conclusion] Replacing medium and low amounts (20%–40%) of chemical fertilizer with green manure not only increased rice yield but also reduced environmental pollution, improved soil nutrients, and optimized the fungal community in soil. This study systematically evaluated the effect of replacing different proportions of chemical fertilizer with green manure on the Ultisol paddy ecosystems. The results provided a theoretical basis for the sustainable development of agriculture in the Ultisol region of southern China.