不同耕作方式对内蒙古旱作农田土壤水热状况的影响

Effects of different tillage systems on soil hydrothermal regimes in rain-fed field of Inner Mongolia

为了研究免耕留茬覆盖和传统耕作土壤水热状况的差异,20052008年在内蒙古呼和浩特市清水河县进行定位试验,结果表明:(1)免耕留茬覆盖能有效的调节土壤温度,出现高温时抑制温度上升,低温时抑制温度降低的现象;土壤温度24h变化的振幅随着土壤深度的增加呈现逐渐减小的趋势,表层010cm的变化幅度最大,变化范围为17.634℃;不同耕作方式的土壤温度均从09:00开始升高,至15:00达到最高值,之后缓慢下降,到06:00达到最低值;土壤温度随季节动态变化的趋势,受制于气候。(2)测定期内免耕留高茬覆盖平均土壤含水量较传统耕作增加了7.37%,免耕留低茬覆盖较传统耕作增加了5.93%;燕麦苗期,不同耕作方式的土壤含水量随土层深度增加,呈增大的态势。分蘖期,不同耕作方土壤含水量在020cm呈下降趋势,之后逐渐升高。燕麦花期,不同耕作方土壤含水量在040cm呈下降趋势,之后逐渐上升,至80100cm土层深度达到最大值;土壤含水量主要受季节影响,随降雨量变化而变化。(3)免耕留茬覆盖耕作方式增加土壤有机质和土壤含水量,其热容量增大,因此能调节和保持温度变化平缓。

Soil hydrothermal regimes can be used for assessing the sustainability of agricultural ecosystems. The objective of this study was to determine the influence of five tillage practices （ no tillage low stubble （ NL）,no tillage high stubble （NH）,no tillage high stubble with residues （NHS）,no tillage low stubble with residues （NLS） and conventional tillage （CT）） on soil temperature and soil moisture content in a degraded oat slope field under dry conditions. Samples taken were at soil depth of 0 80 cm and 0 100 cm layer in the Qing Shuihe county of Inner Mongolia for a period of 4 years. Data were analyzed by the Kriging interpolation method in the SUFER software. The results showed that：（1） There was a significant effect of no tillage with residue on soil temperature and soil temperature followed diurnal variation depending on the season although the magnitude decreased with soil depth. Maximum value of the surface soil layer （0 10 cm） was 17. 6 34. 0℃ ; the soil temperature was lowest at 06：00,the maximum value at 15：00; （2） During whole growth period,soil moisture content of NHS increased by 7. 37% ,NLS by 5. 93% compared to CT：At seeding stage,soil moisture content increased with soil depth up to a depth of 100 cm,at the tillering stage,it was low in 0 20 cm,at flowering stage it was low in 0 40 cm depth,followed by a gradual increase up to 100 cm depth. The moisture content also was affected by season and with the rainfall. （3） Thermal capacity increased as soil organic matter increased and the NHS had a buffering effect on the soil temperature. （ 4 ） In rain-fed areas of the Yellow River basin this study will help the farmland management.