通气与水分再分布对地下滴灌湿润体导气率的影响

Effect of Ventilation and Water Redistribution on Air Permeability of Wetted Soil under Subsurface Drip Irrigation

利用瞬态土壤导气率测算模型,研究了室内模拟地下滴灌土壤导气率的变化,分析了通气与灌后水分再分布对地下滴灌湿润体土壤导气率的影响。结果表明:地下滴灌湿润体内供气压力与时间呈良好的线性关系,导气特征参数与土壤导气率呈极显著的线性关系;容重为1.3、1.4和1.5g/cm3的风干土样在灌水停止时,棕壤土的导气率分别减小至灌水前的8.9%、22.7%和49.9%,塿土的导气率分别减小至灌水前的2.7%、5.4%和9.8%,灌后土壤水分再分布过程中,土壤导气率呈缓慢增长趋势;灌后人工通气可迅速提高地下滴灌湿润体土壤导气率,通气5min后,棕壤土的导气率分别提高至灌水前干土的64.1%、54.1%和79.9%,是停止灌水时的7.3倍、2.5倍和1.6倍,塿土的导气率分别提高至灌水前的79.9%、84.1%和80.8%,是停止灌水时的30.5倍、15.3倍和8.4倍。

In this paper,the transient soil air permeability calculation model is used to investigate the change of soil air permeability under subsurface drip irrigation in lab,analyze the effect of ventilation and water redistribution on the air permeability of wetted soil under subsurface drip irrigation.The results showed that there existed good linear relationship between gas pressure and time,and significant linear relationship between the characteristic parameter of air permeability and soil air permeability in the wetted soil under subsurface drip irrigation;when the irrigation stopped,the air permeability of air-dried brown soil,in which the bulk density were 1.3,1.4 and 1.5 g/cm3,were reduced to 8.9%,22.7% and 49.9%,respectively;and lou soil,in which the bulk density were 1.3 g/cm3、1.4g/cm3 and 1.5 g/cm3,were reduced to 2.7%、5.4% and 9.8%,respectively;in the process of soil water redistribution,the soil air permeability showed slow growth;the artificial ventilation after irrigation could improve the air permeability of the wetted soil rapidly;after five minutes of continuous ventilation,the air permeability of brown soil increased to 64.1%、54.1% and 79.9%,which is 7.3 times,2.5 times and 1.6 times of that of the air-dried soil,and the air permeability of lou soil increased to 79.9%,84.1% and 80.8%,which is 30.5 times、15.3 times and 8.4 times that of the air-dried soil.