稻草还田量对晚稻土微生物数量及活度的动态影响

为了探明翻耕条件下稻草秸秆还田量对土壤生物学特征的影响,确定合理的秸秆还田量,用于早稻秸秆还田培肥土壤,减少环境污染和保障农业可持续性发展,进行了还田量比例为0、33%、67%、100%早稻秸秆覆盖翻耕对晚稻土壤微生物数量及活度的动态影响研究。结果表明,土壤中4类主要微生物的数量和微生物活度在晚稻不同生育期都表现为先升后降的趋势,并且在晚稻分蘖盛期最高。晚稻分蘖盛期无稻草覆盖翻耕土壤的好气性细菌数量最多,33%秸秆量还田土壤的次之,67%和100%秸秆还田土壤的较少,在晚稻收割期,无秸秆还田的土壤中细菌的数量最少。33%秸秆量还田的土壤厌气性细菌的数量最多,而67%和100%还田秸秆量土壤较少,无秸秆还田的最少。在晚稻分蘖盛期无稻草覆盖翻耕土壤的真菌数量最多,在晚稻收割期,有秸秆还田的土壤中真菌数量较无秸秆还田土壤的要多。稻草还田土壤放线菌的数量在晚稻分蘖盛期最多,在晚稻齐穗期,稻草还田土壤放线菌的数量比无稻草还田土壤要多。土壤微生物活度在晚稻分蘖盛期最高,稻草还田土壤的微生物活度要高于无稻草还田的土壤。土壤微生物活度在晚稻齐穗期有所降低,而在晚稻收割时又有所增加,但稻草还田土壤的微生物活度要比无稻草还田土壤的高,且67%稻草还田土壤比33%和100%稻草还田土壤的要低。通过土壤微生物分析评价发现,在翻耕栽培晚稻时,33%的早稻秸秆还田量较好。

Effect of Returning Quantity of Rice-straw to Soil on Quantities and Activity of Microbial in Paddy Soil

Rice-straw was rich in nutrient elements for crop required and was an excellent natural resource for human kinds. There were a large number of straws produced by plants. Most of the rice-straws were incinerated and much harm gas was released to the sky. Returning rice-straw to soil was a reasonable way to solve the environmental problem caused by rice-straw resource loss and improve the soil quality as well as. In addition, the crop could grow well and produce much biomass when the soil was covered with straw. In order to probe into the effect of returning quantity of rice-straw to soil on biological character in soil and provide scientific proof for reasonable applying rice-straw to soil, the tillage with 0, 33%, 67% and 100% of rice-straw to soil in paddy soil was conducted and the microbial flora and their activity were determined respectively at harvesting stage for early maturing rice, maximum tillering stage, maximum booting stage and harvesting stage for late maturing rice. The quantities of aerobic bacteria, anaerobic bacteria, actinomycetes and fungi and their activities in soil were the most at maximum tillering stage of late maturing rice, and were more in soil applied with rice-straw than that in soil without rice-straw. The quantities of aerobic bacteria in soil followed the order: 0 rice-straw to soil >33% rice-straw to soil >67% rice-straw to soil >100 rice-straw to soil during the maximum tillering stage of late-rice, while, the quantities of bacteria in soil without rice-straw were the least at harvesting stage of late rice. The quantities of anaerobic bacteria in soil were: 33% rice-straw to soil>67% rice-straw to soil or 100% rice-straw to soil>0% rice-straw to soil. The trend of fungi in soil was the same as aerobic bacteria. The quantities of actinomycetes in soil covered with rice-straw were more than that without rice-straw. Soil microbial activity could be stimulated by applying rice-straw to soil, showing 67% rice-straw to soil>100% rice-straw to soil>33% rice-straw to soil >0 rice-straw to soil. The results implied that applying 33% rice-straw to soil might be the optimal quantity.