覆膜和降雨强度对玉米耗水过程及土壤水分入渗的影响

【目的】研究农田作物生长过程中,覆膜和降雨特征等因素对玉米耗水过程和土壤入渗产生影响。【方法】根据北京地区典型年降雨量设计和模拟春玉米生育期降雨过程,利用群集式测坑和挡雨棚及附设人工降雨装置,开展了不同地表覆盖条件下降雨强度对玉米耗水及水分利用效率的影响研究。降雨强度包括小雨强0.5 mm/min和大雨强1.5 mm/min,覆盖和种植条件包括膜下滴灌(MDI)、地面滴灌(SDI)和对照无作物种植(NP)。【结果】①MDI处理水分利用效率较SDI处理高13.5%。与SDI处理相比,MDI处理作物耗水量减小了40.6 mm,覆膜主要提高20～60 cm土层储水量。②大雨强条件下土壤深层渗漏量增多了3.4%～15.6%;降雨和灌溉对土壤水分影响深度主要为0～150 cm土层,相对于SDI处理,MDI和NP处理土壤储水量大大增加。③小雨强时表层0～20cm土壤入渗NP处理最快,大雨强时MDI处理入渗最快。作物根区40 cm深度处,小雨强时MDI处理的土壤水分最快达到峰值,而大雨强时NP处理最快达到峰值。60 cm深度处不同覆盖条件下在2种雨强时土壤水分变化速率一致,达到峰值速率表现为NP处理>MDI处理>SDI处理。【结论】覆膜具有较好的节水增产效应;降雨强度越大,土壤水分下渗越快;相同降雨量时小雨强降雨更有利于土壤水存储。不同的降雨强度对土壤水分入渗和再分布影响不同。研究结果可为雨水资源的合理利用从而提高农田水分利用效率提供理论依据。

Effects of Mulching and Rainfall Intensity on Soil Water Infiltration and Water Consumption for Maize

With increasing shortage of water resources in irrigation district in North China, it is in need and very important to make full use of rainfall and improve the water use efficiency in agricultural production. 【Objective】Under this situation, the key studies are to learn the rule of soil water infiltration, movement, and redistribution at different surface mulching and irrigation method. 【Method】In this paper, multiple lysimeters were employed to carry out experiments of maize water consumption in different rainfall intensity and ground cover, companying with the rain shelter and artificial rainfall facility. Artificial rainfall amount and their process in crop growth season were designed and simulated based on frequency analyses of 60 years in Beijing area. 2 rainfall intensities were 0.5 mm/min(small) and 1.5 mm/min(big). There were 3 treatments set up to compare the maize water consumptions and soil water infiltration, including of Mulching Drip Irrigation(MDI), Surface Drip Irrigation(SDI) and contrast treatment of bare soil(No Plant, NP), respectively. 【Result】①The water use efficiency of MDI increased by 13.5%than SDI, which indicated that mulching had significant effect on water saving and increasing crop yield. Water consumption of MDI decreased 40.6 mm comparing with the SDI. Mulching supported significant contribution to soil moisture in 20～60 cm depth. ②The soil deep seepage increased 3.4%～15.6% than small one at 1.5 mm/min rainfall intensity. The main soil depth in crop root zone was 0 ～ 150 cm affected by rainfall and irrigation to soil water movement. The soil water storages of MDI and NP were larger than the SDI in 0 ～ 240 cm. However, the rainfall intensity had less effect to the soil water storage in whole 0～240 cm. But the small rainfall intensity profited it at same rainfall. ③At the top of 0～20 cm, soil infiltration rate was biggest in NP treatment at rainfall intensity of0.5 mm/min, and the MDI was the biggest at 1.5 mm/min. The soil water content reached peak at the depth of 40 cm under MDI treatment at rainfall intensity of 0.5 mm/min and the NP was the fastest at 1.5 mm/min. At the depth of60 cm, the soil water filtration appeared as order by NP > MDI > SDI, whatever at small rainfall intensity or big. At the same time, the soil water content change rate was faster at rainfall intensity of 1.5 mm/min than the small.【Conclusion】Infiltration rate of soil water sends up clearly when rainfall intensity increase. Rainfall intensity affect the soil water infiltration and redistribution. Those results could support the high utilization of natural rainfall resources and promoting water use efficiency in agricultural field.