旱作农田不同耕作土壤呼吸及其对水热因子的响应

Soil respiration and its responses to soil moisture and temperature under different tillage systems in dryland maize fields

为研究旱作农田春玉米生育期不同耕作土壤呼吸变化特征及其对水热因子的响应情况,在山西省寿阳县旱农试验基地采用红外气体分析法测定了传统耕作(CT)、少耕(RT)和免耕(NT)土壤呼吸速率,并同步测定了各土层土壤水分、温度。研究表明:在春玉米生育期内,土壤呼吸速率均呈单峰型变化趋势,峰值出现在8月;传统耕作与少耕土壤呼吸速率变化趋势基本一致,而免耕土壤与前两者相比波动幅度较大;土壤呼吸峰值与水分、温度之间无明显相关,其余时期土壤呼吸与水分、温度因子具有良好的相关性;双因子模型较单因子模型能更好的描述土壤呼吸与水分、温度之间关系,基于水热双因子(10—20 cm)的指数-幂模型能够解释土壤呼吸变化的81%—87%(P<0.01);3种耕作土壤呼吸对水热因子协同影响的敏感性表现为CT>NT>RT。

Soil respiration and its responses to soil moisture and soil temperature under different tillage systems during the period of spring maize growth were investigated in Shouyang Dryland Farming Experimental Station, Shanxi Province, China. The soil respiration rate, soil moisture and soil temperature were determined by dynamic chamber-IRGA method, in the maize field, with three tillage practices, including conventional （CT）, reduced （RT）, and no-till （NT）. The results showed that the changes in soil respiration rates had a single peak curve, and its peak appeared in August The seasonal variations in soil respiration rates under CT, RT and NT were 0.50-4.81, 1.11-5.44 and 0.40-5.89 μmol CO2 m-2·s-1, respectively. The trends in soil respiration between CT and RT were similar, while there was a larger fluctuation in soil respiration with NT. The regression analysis showed that soil respiration had a significant correction with soil moisture or temperature, but little at the peak values of soil respiration. Soil moisture （0-10 cm） could explain 57%-76% of seasonal variations in the soil respiration. The moisture sensitivities of soil respiration were NT〉RT〉CT. Soil temperature （15 cm） could explain 67%-82% of seasonal variations in the soil respiration. the Q10 was NT （2.47）〉RT （2.02）〉CT （1.59）. The two-factor model y=aebTWc or y=a＋bT＋cW could better describe the relationship between soil respiration and combination of soil moisture and temperature than the one-factor model. The index-power model of combination of soil moisture and temperature （10-20 cm） y=aebTWc can explain 81%-87% of variations in soil respiration （P〈0.01）. The sensitivities of three tillage treatments to the combination of soil moisture and temperature were： RT〉CT〉NT. Soil respiration was affected differently by the hydrothermic factor or by each of the single factor.