不同水分条件下椰壳炭施用对稻田土壤酶活性及微生物群落的影响

以热带稻田土壤为研究对象，利用室内短期恒温(25°C)培养探讨好氧和淹水条件下椰壳炭不同施用量(0%、2%和5%(w/w))对土壤性质和微生物群落的影响。结果表明：①培养35 d后，好氧和淹水条件下增施2% 和5% 椰壳炭均提升土壤pH，增幅分别为20%、39%和31%、32%。好氧下土壤脲酶活性增加121% 和75%，酸性磷酸酶活性降低10% 和49%，碱性磷酸酶活性提高39% 和39%；淹水下脲酶活性减少12% 和45%，酸性磷酸酶活性降低3% 和14%，碱性磷酸酶活性增加133% 和105%。②增施2% 和5% 椰壳炭时，好氧下土壤细菌和真菌香农指数均降低，但淹水时增加。好氧下变形杆菌门(Proteobacteria)、芽单胞菌门(Gemmatimonadetes)和浮霉菌门(Planctomycetes)丰度提高，增幅分别为2%、54%，51%、47% 和94%、82%；淹水下酸杆菌门(Acidobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)丰度增加，增幅分别为3%、20%，14%、18% 和38%、37%；同时好氧和淹水下土壤担子菌门(Basidiomycota)丰度均下降，降幅分别为68%、70% 和68%、76%，并且淹水下壶菌门(Chytridiomycota)和罗兹菌门(Rozellomycota)丰度增加。该研究结果可为椰壳炭对稻田土壤改良及其推广应用提供参考。

Effects of Coconut Shell Biochar on Enzyme Activities and Microbial Community in Tropical Paddy Soil Under Different Water Conditions

Tropical paddy soil samples were collected, and the effects of different application rates of coconut shell biochar (0%, 2% and 5% (w/w)) on soil properties and microbial communities under aerobic and flooded conditions in 25 ℃ were studied by the incubation experiment. The results showed that, 1) after 35 day-incubation, 2% and 5% coconut shell biochar improved soil pH under both aerobic and flooded conditions, which increased by 20% and 39%, 31% and 32%, respectively. Under aerobic conditions, soil urease activity increased by 121% and 75%, acid phosphatase activity decreased by 10% and 49%, and alkaline phosphatase activity increased by 39% and 39%; Under flooding, soil urease activity decreased by 12% and 45%, acid phosphatase activity decreased by 3% and 14%, and alkaline phosphatase activity increased by 133% and 105%. 2) When adding 2% and 5% coconut shell biochar, Shannon index of soil bacteria and fungi decreased under aerobic conditions, but increased under flooding. Under aerobic conditions, the abundances of Proteobacteria, Gemmatimonadetes and Planctomycetes increased by 2% and 54%, 51% and 47%, 94% and 82%, respectively. Under flooding, the abundances of Acidobacteria, Firmicutes, and Bacteroidetes increased by 3% and 20%, 14% and 18%, 38% and 37%, respectively. Meanwhile, the abundance of soil Basidiomycota decreased under aerobic and flooded conditions, which decreased by 68% and 70%, 68% and 76%, respectively, and the abundances of Chytridiomycota and Rozellomycota increased under flooded conditions. The research results can provide data reference for the improvement and promotion application of coconut shell biochar in tropical paddy soil.