紫云英还田对黄泥田土壤理化和微生物特性及水稻产量的影响

为探明紫云英连年还田化肥减施单季稻田土壤性质及水稻产量的变化规律，依托位于福建省东部12年黄泥田紫云英-单季稻轮作定位试验，研究了不施肥（C₀）、单施化肥（C₁₀₀）、紫云英还田（M）、紫云英还田+全量化肥（MC₁₀₀）及紫云英还田+减量20%化肥（MC₈₀）处理的土壤理化性状、微生物群落结构和功能及稻谷产量的变化。结果表明：C₁₀₀、M、MC₁₀₀、MC₈₀处理土壤有机碳含量比C₀分别提高6.97%、15.05%、10.38%、11.15%，全氮分别提高9.52%、18.25%、15.87%、15.87%，硝态氮分别提高6.51%、69.52%、66.87%、78.19%（P < 0.05）。冗余分析表明，土壤有机碳、全氮、硝态氮含量对细菌和古菌群落结构和功能有显著的影响。与C₀相比，C₁₀₀、M、MC₁₀₀和MC₈₀处理土壤慢生根瘤菌属（Bradyrhizobium）丰度分别增加0.52%、24.30%、7.59%、11.93%，其中M处理增加达显著水平（P<0.05）；分枝杆菌属（Mycobacterium）分别增加5.51%、21.58%、10.00%、14.74%，其中M处理增加显著（P<0.05）；亚硝化杆菌属（Candidatus_Nitrosotalea）分别增加22.93%、17.21%、65.39%、89.89%，其中MC₁₀₀和MC₈₀处理增加均达显著水平（P<0.05）。相比C₀，M、MC₁₀₀和MC₈₀处理土壤链霉菌属（Streptomyces）分别增加6.76%、16.89%、12.16%，其中MC₁₀₀处理增加显著（P < 0.05），而C₁₀₀却减少2.50%。物种贡献度分析发现，土壤碳代谢和氨基酸合成的主要功能微生物为细菌慢生根瘤菌属（Bradyrhizobium）、分枝杆菌属（Mycobacterium）、链霉菌属（Streptomyces）和古菌亚硝化杆菌属（Candidatus_Nitrosotalea）。M、MC₁₀₀、MC₈₀处理稻谷产量比C₀分别增加9.68%、19.16%、18.72%。阐明紫云英培肥处理能提升单季稻黄泥田土壤肥力水平，调节土壤微生物群落结构，促进土壤碳水化合物和氨基酸代谢。

Impacts of the Chinese milk vetch (Astragalus sinicus L.) residue incorporation on soil physicochemical, microbial properties and rice yields in yellow-mud paddy field

To evaluate the effects of milk vetch (Astragalus sinicus L.) residue combined with different rates of chemical fertilizers on soil properties and rice yields in a yellow-mud paddy field, a 12-year field experiment in eastern Fujian Province was conducted to investigate soil physicochemical properties, microbial community structure and function, and rice yields in the C₀ (without fertilization), C₁₀₀ (chemical fertilizers), M (Chinese milk vetch), MC₁₀₀ (Chinese milk vetch combined with 100% chemical fertilizers), and MC₈₀ (Chinese milk vetch combined with 80% chemical fertilizers) treatments. Results showed that soil organic carbon (SOC) concentration in the C₁₀₀, M, MC₁₀₀ and MC₈₀ treatments increased by 6.97%, 15.05%, 10.38%, 11.15%, total nitrogen (TN) increased by 9.52%, 18.25%, 15.87%, 15.87%, and nitrate nigrogen (NO₃^--N) increased by 6.51%, 69.52%, 66.87%, 78.19% compared with those in the C₀ treatment, respectively (P<0.05). Furthermore, SOC, TN, and NO₃^--N concentrations were the main factors driving the variation in soil bacterial, archaeal community structure and function under different fertilization regimes using redundancy analysis. In addition, the relative abundance of the bacterial genus Bradyrhizobium in the C₁₀₀, M, MC₁₀₀ and MC₈₀ treatments increased by 0.52%, 24.30%, 7.59%, 11.93%, and a significant increase in the relative abundance of Bradyrhizobium was found in the M treatment (P<0.05); the abundance of Mycobacterium increased by 5.51%, 21.58%, 10.00%, 14.74%, and a significant increase in the relative abundance of Mycobacterium was found in the M treatment (P<0.05); the abundance of the archaeal genus Candidatus_Nitrosotalea increased by 22.93%, 17.21%, 65.39%, 89.89% compared with those in the C₀ treatment, respectively, and a significant increase in the relative abundance of Candidatus_Nitrosotalea was found in the MC₁₀₀ and MC₈₀ treatments (P<0.05); in addition, the relative abundance of Streptomyces in the M, MC₁₀₀ and MC₈₀ treatments increased by 6.76%, 16.89%, 12.16%, and a significant increase in the relative abundance of Streptomyces was found in the MC₁₀₀ treatment (P<0.05), whereas decreased by 2.50% in the C₁₀₀ treatment comparing with the C₀ treatment. Compared with the C₀ treatment, the M, MC₁₀₀ and MC₈₀ treatments increased the average rice yield by 9.68%, 19.16%, 18.72%, respectively. Soil microbial genus-functional contribution analysis revealed that the bacterial genera Bradyrhizobium, Mycobacterium, Streptomyces, and the archaeal genus Candidatus_Nitrosotalea were the key drivers of the top two kinds of functions:amino acid and carbon metabolism under different fertilization regimes. In general, these findings indicate that the Chinese milk vetch residue incorporation might ameliorate soil properties, regulate soil microbial community structure, accelerate metabolism of amino acids and carbohydrates in a yellow-mud paddy field in a single rice cropping system.