膜下滴灌灌水量对土壤水热影响及地下水补给耗水响应

为探求灌水量对棉田地温和生育期地下水补给棉花耗水比例的影响,设置了4种不同膜下滴灌灌水量(3 000,3 750,4 500,5 250m~3/hm~2)进行野外均衡场试验研究。结果表明:灌水量一定时,浅层土壤受气温影响更为显著;同一气象条件下、同一土层地温和土壤有效积温均随灌水量的增加而降低,当灌水量增加75%时,有效积温降低11.3%,同时温度变幅也相对变小;灌水量越大,棉花耗水量及地下水补给作物水量也随之增大。当灌水量从3 000m~3/hm~2增加到5 250m~3/hm~2时,棉花的耗水量增加146.3%,地下水补给比例增加540%,而棉花需水敏感期地下水补给量则增加152.93mm,需水敏感期的地下水补给量最大,但日均地下水补给量随棉花生育期的延长而增大,且各处理的水分利用效率差异不大。此外,在地温较高的夏季高温期(花铃期和吐絮期)以及灌水量较小时,夜间地下水补给作物水量大于或接近白天补给量,说明地温影响地下水的向上补给水量和补给时段。此研究可为合理高效利用农业水资源和优化膜下滴灌棉花灌溉制度提供有效依据。

Changes of Soil Temperature and Water Supply from Groundwater to Crop Under Different Irrigation Amount with Drip Irrigation Under Plastic Mulch

Drip irrigation under plastic mulch can effectively improve soil water and heat conditions,and increase crop yield.Moreover,change range of soil water,heat and crop yield as well as water supply from groundwater are maily effected by irrigation amount.To explore the effect of irrigation on soil and water consumption to groundwater recharge ratio of cotton in the growth period,four treatments with different irrigation amount(3 000 m3/hm2,3 750 m3/hm2,4 500 m3/hm2,5 250 m3/hm2)were conducted and the effects of irrigation amount on soil temperature and water supply from groundwater were investigated during the growth period of cotton by the balance plots.The results showed that,at a given irrigation amount,the shallow soil was more easily affected by the atmospheric temperature;under the same meteorological conditions,soil temperature and effective accumulated temperature at the same layer decreased with increasing irrigation amount,when the irrigation amount was increased by 75％,effective accumulated temperature decreased by 11.3％,while the temperature changes were relatively small;the greater the irrigation amount,the greater the water consumption of cotton and the amount of water in the groundwater supply.When the irrigation water was increased from 3 000 m3/hm2 to 5 250 m3/hm2,the water consumption of cotton increased by 146.3 ％,groundwater recharge rate increased by 540％,the water supply in the sensitive period of cotton increased by 152.93 mm,and the amount of groundwater recharge in the water sensitive period was the greatest,but daily groundwater recharge increased with the increase of cotton growth period,and the water use efficiency of each treatment was not significantly different.Furthermore,it was found that at the conditions of higher soil temperature in summer (flowering and boll opening stage) and the lower irrigation amount,the amount of water supply from groundwater in the night was greater than or close to that in the daytime.The results of this study will provide an effective basis for using agricultural water resources rationally and efficiently and optimizing the irrigation system of drip irrigation under plastic mulch.