多年覆膜改善冬小麦/油菜轮作地土壤提高产量

摘要

Whole plastic film mulching is commonly used for crops on the Loess Plateau, which can significantly improve rainfall use efficiency and crop productivity. However, no systematic analysis of the productivity increment and soil microbial environmental effects of this technique has been undertaken previously. A field experiment was conducted from 2012 to 2016 to study the effects of whole plastic film mulching on soil microbial biomass carbon, soil microbial biomass nitrogen, soil enzyme activities, soil moisture and temperature. The 3 treatments applied were: whole plastic film mulching with soil covering and bunch seeding (M1), whole plastic film mulching and bunch seeding (M2), and soil uncovered and bunch seeding (M0). The soil water content and soil temperature were recorded, and the soil microbial biomass carbon, soil microbial biomass nitrogen, and soil enzyme activities were calculated. The M1 and M2 treatments averagely increased the soil moisture content by 3.83%-15.85% and 2.53%-15.53%, soil temperature by 0.9-1.7 and 0.8-2.7 ℃ respectively compared with M0 before winter wheat jointing stage and rape flowering stage. As compared with M0, both M1 and M2 treatments averagely increased soil microbial biomass carbon content by 25.64% and 23.55% from winter wheat re-greening to jointing stage, and by 24.70% and 24.63% from rape re-greening stage to flowering stage, significantly. As compared with M0, both M1 and M2 treatments averagely increased soil microbial biomass nitrogen content by 20.42% and 12.65% from winter wheat re-greening stage to jointing stage, and by 18.41% and 15.35% from rape re-greening stage to bud stage, significantly. As compared with M0, the urease enzyme activities of M1 and M2 were significantly higher at each growth stage of winter wheat and rape (except winter wheat booting, maturing stage in 2013), and the sucrase enzyme activity of M1 was significantly higher at each growth stage of winter wheat and rape, whereas alkaline phosphatase enzyme activity of M1 was lower (except winter wheat maturing stage in 2013). The increased extent of soil thermal-moisture status and soil microbial activities was higher in 2015 and 2016. There is a positive correlation between soil microbial biomass carbon, microbial biomass nitrogen, urease enzyme, sucrase enzyme and soil moisture and soil temperature. Based on the regulatory effect of soil thermal-moisture status and microbial activities, compared with M0, the winter wheat yield of M1 and M2 increased by 30.44% and 22.25%, and the rape yield of M1 and M2 increased by 21.36% and 14.02%, respectively. The increased extent of yield and water use efficiency was higher in a dry year than that in a wet year. Consequently, whole plastic film mulching ameliorated soil thermal-moisture status in dry spring, and increased soil microbial biomass carbon content, microbial biomass nitrogen content, urease enzyme activity, sucrase enzyme activity, and crop yield.%全膜覆盖已成为西北干旱半干旱地区农作物的最佳种植模式,可显著提高降水利用率和作物生产力,但目前对其土壤微生物环境效应缺乏系统研究分析.2012-2016年在甘谷采用田间试验方法,比较了露地穴播(M0)、全膜覆土穴播(M1)和全膜穴播(M2)冬小麦和油菜各生育期土壤含水量、温度、微生物量、酶活以及产量的变化.结果表明:与M0处理相比,M1和M2在冬小麦拔节和油菜开花前的土壤含水量分别提高3.83%~15.85%和2.53%~15.53%;土壤温度分别平均提高0.9~1.7 ℃和0.8~2.7 ℃.在冬小麦返青期-拔节期,M1和M2的土壤微生物量碳较M0分别平均增加25.64%和23.55%;在油菜返青期-开花期,M1和M2的土壤微生物量碳较M0分别平均增加24.70%和24.63%,显著差异.在冬小麦返青期-拔节期,M1和M2的土壤微生物量氮较M0分别平均增加20.42%和12.65%;在油菜返青期-苗薹期,M1、M2的土壤微生物量氮较M0显著增加.M1和M2冬小麦和油菜各生育期的脲酶活性显著高于M0(除2013年冬小麦的孕穗期和成熟期).冬小麦和油菜各生育期的蔗糖酶均表现为M1高于M0,而碱性磷酸酶则表现为M1低于M0(除2013年冬小麦的成熟期).且在2014-2015和2015-2016年全膜穴播增温保水,提高土壤微生物活性的效果较为明显.土壤微生物量碳、氮含量,脲酶,蔗糖酶与土壤含水量、土壤温度温度呈相关或极显著相关.基于对土壤水热环境和微生物活性的影响,M1和M2分别比M0的冬小麦产量增加,而且干旱年份的增加幅度更高.