不同轮作方式和秸秆还田对麦田土壤CO_2排放与水热碳氮状况和产量的影响

Effects of different rotation modes and straw returning on soil CO_2 emission fluxes and moisture, heat, carbon and nitrogen conditions in wheat field

为探讨免耕条件下不同轮作方式秸秆还田对土壤CO2排放的影响,本研究通过长期定位试验,采用GXH-3010E1型便携式红外线分析器测量土壤CO2排放速率,对比研究冬小麦-夏闲、冬小麦-夏玉米和冬小麦-夏大豆在秸秆还田条件下土壤CO2排放的动态变化及其与土壤温度、水分之间的回归关系,并分析比较土壤有机碳和碱解氮含量的变化。结果表明:三种轮作方式秸秆还田条件下冬小麦土壤CO2排放具有明显的季节变化规律,平均CO2排放通量表现为冬小麦-夏玉米全量还田>冬小麦-夏玉米不还田>冬小麦-夏大豆全量还田>冬小麦-夏大豆不还田>冬小麦-夏闲全量还田>冬小麦-夏闲不还田。所有处理土壤CO2排放通量与土壤含水率和土壤温度均呈极显著正相关,秸秆未还田处理地温与CO2排放通量的模拟模型要好于秸秆还田处理。各处理冬小麦收获后土壤有机碳和碱解氮含量均比播种前高,FA、FN处理有机碳增加最大,SA、SN碱解氮增加最大。

In order to explore the effect of different rotation modes and straw returning on soil CO2 emission under no-till condition,GXH-3010E1 portable infrared analyzer was used to measure the soil CO2 emission rate in a long-term field experiment .The dynamic variation of CO2 emission fluxes under different rotation modes （winter wheat-summer fal-low,winter wheat-summer maize,winter wheat-summer soybean）and the relationship between soil CO2 emission and soil temperature as well as soil moisture were compared,and the changes of soil organic carbon and alkali-hydrolyzable nitro-gen were analyzed .The results showed that the CO2 emission fluxes fluctuated clearly with different seasons .The order of CO2 emission fluxes were：winter wheat-summer maize and whole straw returning（MA）〉winter wheat-summer maize and no straw returning（MN）〉winter wheat-summer soybean and whole straw returning（SA）〉winter wheat-summer soybean and no straw returning（SN）〉winter wheat-summer fallow and whole straw returning （FA）〉winter wheat-summer fallow and whole straw returning（FN）.There was highly significant positive relationship between soil CO2 emission fluxes and soil temperature as well as soil moisture under all treatments,and the simulation models between soil temperature and CO2 emission fluxes under no straw returning were better than those under straw returning .The contents of soil organic carbon and alkali-hydrolyzable nitrogen after harvesting of wheat increased,compared to those before seeding .The soil organic carbon was increased most under FA and FN,while the alkali-hydrolyzable nitrogen was increased most under SA and SN .