不同耕作方式麦田土壤温度及其对气温的响应特征 ——土壤温度日变化及其对气温的响应

 【目的】针对以往研究在土壤温度观测和不同耕作条件下土壤温度效应规律上的不足，研究了华北平原不同耕作方式冬小麦田土壤温度日变化及其对气温的响应特征。【方法】试验于河北省栾城县设置翻耕、旋耕和秸秆覆盖免耕处理，采用热脉冲-时域反射技术，连续监测2004-2005年冬小麦生育期土壤温度和气温。【结果】各层次土壤温度日变化随气温呈正弦函数变化;土壤温度日变化随土壤深度呈“锥形”;2.5～80 cm土壤深度每增加5 cm，土壤温度随气温的变化滞后1.2 h左右;不同耕作方式土壤日最高和最低温度均具有显著差异，秸秆覆盖度是其主要影响因素之一;免耕在冬小麦活动期，显著降低了2.5 cm土层土壤最高温度0.66～4.85℃，而在越冬期提高最低温度0.64～0.87℃;冬小麦生长前期（出苗-拔节）免耕较其他处理显著降低了2.5 cm土层土壤温度日变化幅度，其中较翻耕降低0.65～5.21℃，较旋耕降低0.48～3.89℃。【结论】不同耕作方式各层次土壤温度均极显著响应气温变化;耕作方式主要影响土壤温度的变化幅度而且主要表现在冬小麦生长前期;免耕在冬小麦活动期表现为降温效应，究其原因是由于较大程度地降低高温而较小程度地提高低温;越冬期表现增温效应是由于显著提高了各个时刻的土壤温度。

Characteristics of Soil Temperature and Response to Air Temperature Under Different Tillage Systems——Diurnal Dynamic of Soil Temperature and Its Response to Air Temperature

【Objective】Earlier techniques made the measurement and analysis of soil temperature uncertain. Tillage effects on soil temperature are insufficiency at previously studies. An experiment was conducted to characterize the tillage effects of diurnal dynamic of soil temperature and its response to air temperature in winter wheat field, North China Plain. 【Method】 Conventional tillage (CT), rotary tillage (RT) and no tillage with stubble covered (NT) were treated from 2004 to 2005 at Luancheng Station of Hebei Province. Temperature was measured continuously by thermo-time domain reflectometry. 【Result】 Results showed that the diurnal dynamic of each layer soil was a sine wave; the diurnal temperature fluctuation was a taper and soil temperature was delayed by 1.2 h per 5 cm increment of soil depth from 2.5-80 cm; diurnal highest and lowest soil temperature was significantly affected by different tillage systems with one of the reason was residue covering ratio; diurnal highest soil temperature at 2.5 cm layer was decreased by 0.66-4.85℃ under NT at active stages of winter wheat, but it was increased by 0.64-0.87℃ at overwintering stage; diurnal soil temperature fluctuation range at the 2.5 cm layer was decreased significantly by 0.65-5.21℃ and 0.48-3.89℃ at early stages (emergence -jointing) of winter wheat under NT, compared with CT and RT, respectively. 【Conclusion】 Soil temperature responses to air temperature significantly under different tillage systems. The main characteristic of tillage effects on soil temperature is that the extentence of soil temperature fluctuation is changed significantly at early stages of winter wheat. More decrease in high temperature and less increase in low temperature are the reasons that NT shows a lower temperature effect at active stages. NT with higher temperature at each time of day results in higher temperature effect at hibernation of winter wheat.