灌水梯度及覆膜组合模式对滴灌棉田蒸散规律的影响

Effects of irrigation gradients and film mulching combinations on evapotranspiration in drip-irrigated cotton field

为研究地膜覆盖与灌水对棉田蒸散量及水热状况的影响,开展测坑和桶栽试验,设置三个灌水水平:3360(W1)、4200(W2)、5040 m^(3)·hm^(-2)(W3);两种地膜覆盖方式:覆膜(P1)和裸土(P2)。结果表明:(1)覆膜能有效降低棉花全生育期总蒸散量,W1、W2、W3灌溉水平下,覆膜处理棉花蒸散量分别降低25.31%、25.39%、25.75%。灌水量与蒸散量呈正相关关系,P1方式下,W3处理比W1、W2处理棉花蒸散量分别提高8.71%、7.50%;P2方式下,W3处理比W1、W2处理棉花蒸散量分别提高8.82%、8.02%。(2)覆膜能改变棉田土壤水热状况,可有效提高土壤温度和土壤含水率,覆膜对土壤水热状况的影响随土壤深度的增加而减弱;土壤温度与灌水量呈负相关关系,土壤含水率与灌水量呈正相关关系。(3)土壤含水率对裸土处理棉花蒸散量的相关系数影响最大,并随着土层深度的增加而降低;土壤温度对棉花蒸散量的相关系数随土层深度增加而升高,P1处理在20 cm土层相关系数最高,P2处理则在25 cm土层最高。探索覆膜滴灌对干旱区农田蒸散过程的影响对理解绿洲水文循环过程具有重要的理论意义,同时也可为干旱区有限水资源合理利用提供科学参考。

To examine the effects of plastic film coverage and irrigation on evapotranspiration as well as water and heat conditions in cotton fields,pit and barrel planting experiments were conducted.The experiments involved three irrigation levels:3360 m^(3)·hm^(-2)(W1),4200 m^(3)·hm^(-2)(W2),and 5040 m^(3)·hm^(-2)(W3),along with two plastic film covering methods:covered with film(P1)and bare soil(P2).The evapotranspiration pattern and soil water and heat status of drip irrigated cotton fields were analyzed.The results showed that:(1)Plastic film mulching effectively reduced the total evapotranspiration of cotton throughout the entire growth period.Under W1,W2,and W3 irrigation levels,the plastic film mulching treatment reduced cotton evapotranspiration by 25.31%,25.39%,and 25.75%,respectively.The irrigation amount was positively correlated with evapotranspiration.Under P1 mode,the cotton evapotranspiration of W3 treatment increased by 8.71%and 7.50%compared to W1 and W2 treatments,respectively.Under P2 mode,the cotton evapotranspiration of W3 treatment increased by 8.82%and 8.02%,respectively.(2)Film mulching had a considerable impact on the soil temperature and moisture content of the cotton fields,leading to an increase in soil temperature and moisture content.However,the impact of film mulching on soil water and thermal conditions diminished as soil depth increased.Additionally,there was a negative correlation between soil temperature and irrigation amount,and a positive correlation between soil moisture content and irrigation amount.(3)Soil moisture content was found to have the greatest influence on the correlation coefficient of cotton evapotranspiration in the bare soil treatment,and it decreased with increasing soil depth.On the other hand,the correlation coefficient of soil temperature on cotton evapotranspiration increased with soil depth.It is worth noting that the P1 treatment had the highest correlation coefficient in the 20 cm soil layer,while the P2 treatment had the highest correlation coefficient in the 25 cm soil layer.Exploring the impact of film mulching and drip irrigation on the evapotranspiration process of farmland under water-saving conditions in arid regions is of great theoretical significance.This research helps in understanding the hydrological cycle and stability mechanisms of oases.Additionally,it provides valuable scientific insights for optimizing and utilizing limited water resources in arid areas.