秸秆还田配施化肥及微生物菌剂对水田土壤酶活性和微生物数量的影响

土壤微生物学特性是表征土壤质量的重要生物学指标。通过田间试验研究了秸秆还田配施不同配比化肥及微生物菌剂对水田土壤酶活性和微生物数量的影响。结果表明,与单施秸秆相比,秸秆还田配施N、P、K及微生物菌剂后,土壤过氧化氢酶、转化酶和尿酶活性分别提高了37.5%~68.8%、32.3%~61.5%和48.8%~102%,细菌和真菌数量分别提高了95.3%~174%、286%~351%,放线菌数量减少了34.5%~39.4%,差异显著。统计分析显示,土壤过氧化氢酶与尿酶活性之间及其酶活性与微生物数量之间关系密切。氨化细菌和硝化细菌数量主要控制土壤过氧化氢酶活性,真菌数量是转化酶活性的主要影响因素,而尿酶活性主要受细菌数量影响。秸秆还田配施微生物菌剂及平衡施肥可以促进酶活性的增强,使土壤微生物群落物种个体数增加更多,分布更为均匀。过量施用氮肥会抑制土壤酶活性和微生物的生长和繁殖。

Effects of returning rice straw to fields with fertilizers and microorganism liquids on soil enzyme activities and microorganisms in paddy fields

Paddy rice straw is widely used to improve soil fertility in China by returning it back to the fields after harvest.However,the straw’s nutrients need a long time to be plant available.This paper examined how to accelerate the nutrients transformation to be plant available within a short period of time.In particular,the paper studied the causal connection between returning straw to fields with varying application of fertilizers and microorganism liquids on soil enzyme activities and the number of microorganisms in paddy fields.The investigation has been carried out in Experiment Base of Jiangxi Agriculture University,Nanchang,Jiangxi Province.Surface soil samples were collected from paddy fields.The experiment included eight components ranging from straw purely,straw with N-fertilizer,straw with compound fertilizer,and straw with microorganism liquids.In detail,the following fertilizer applications have been used：（1） straw 3 000 kg.hm-2.a-1,（2） straw 3 000 kg.hm-2.a-1with Nitrogen 150 kg.hm-2.a-1,（3） straw 3 000 kg.hm-2.a-1with N 225 kg.hm-2.a-1,（4） straw 3 000 kg.hm-2.a-1 with P2O5 75 kg.hm-2.a-1,（5） straw 3 000 kg.hm-2.a-1 with P2O5112.5 kg.hm-2.a-1,（6） straw 3 000 kg.hm-2.a-1 with N 150 kg.hm-2.a-1,P2O5 75 kg.hm-2.a-1,and K2O 37.5 kg.hm-2.a-1,（7） straw 3 000 kg.hm-2.a-1 with N 225 kg.hm-2.a-1,P2O5 112.5 kg.hm-2.a-1,and K2O 56.3 kg.hm-2.a-1,（8） straw 3 000 kg.hm-2.a-1with microorganism liquids 15 L.hm-2.a-1.The relationship between soil enzyme activities and microorganisms were determined by multivariate statistical analysis.In contrast to returning straw only to the field（treatment 1）,the results showed that combined application of straw with NPK fertilizers and microorganism liquids increased soil catalase（37.5%-68.8%）,invertase（32.3%-61.5%）,urease activities（48.8%-102%） significantly.Furthermore,the population of both,bacteria and fungi in soil rose by 95.3%-174% and 286%-351%,respectively,while the population of actinomycetes decreased by 34.5%-39.4%.Soil catalase activities were statistically significantly positively correlated with urease activities.The trial provided evidence on the close correlation between microorganisms and enzyme activities in the soil.Soil catalase activities were mainly determined by the quantity of ammonifying bacteria and nitrifying bacteria.The quantity of fungi has been identified as an important influencing factor of soil invertase activities.Soil urease activities were mainly determined by the quantity of bacteria.After straw’s returning to field with NPK and microorganism liquids,the field experiment results showed,soil enzyme activities were improved,and the number of species and individual microbial communities in soil increased and were distributed more evenly.However,excessive application of nitrogen fertilizer would restrain the enzyme activities as well as the growth and reproduction of soil microorganisms.