河北低平原区咸水滴灌棉田水盐耦合模拟与适宜灌溉指标

As water shortage and land conflicts between grain and cotton production are becoming increasingly serious, to develop the cotton planting in saline dryland and saline water irrigation techniques has become an inevitable trend. Based on our investigations on secure utilization of saline water for cotton in recent years, a further study on effects of different combinations of irrigation water salinity and lower control limit for cotton with mulched drip irrigation upon soil water-salt migration, soil environmental quality as well as cotton growth processes will be carried out. Coupling simulation of soil water-salt movement in cotton field was established. Soil salt balance and corresponding regulation mechanism will be discussed, salt tolerance and water demanding of cotton will be developed. The influences of different treatments upon soil environment, water utilization, cotton yield and fiber quality will be investigated, thereafter, the availability of saline water under mulched drip irrigation will be presented. The suitable irrigation indices and irrigation schedule will be determined to achieve the efficient use of saline water resources, soil environment protection and high yield of cotton with top quality. The study is helpful for the well reclamation of dry land and saline land in the Hebei Low Plain, and ensure food security and cotton growing area, which has profound significance for the sustainable development of regional social economy and ecological environment.

随着淡水资源短缺和粮棉争地形势的日益严峻，大力发展盐碱旱地植棉和棉花咸水安全灌溉技术成为必然趋势。本项目拟在申请者近几年棉花咸水安全利用研究的基础上，进一步研究膜下滴灌方式下不同灌溉水矿化度和灌水控制下限相组合对棉田水盐运移过程、土壤环境质量以及棉花生长发育的影响效应，建立棉田水盐耦合运移模型，探讨土壤盐分均衡和调控机制，揭示棉花耐盐特性与需水规律。结合不同处理对土壤环境及棉花产量、品质和水分利用的综合影响，明确膜下滴灌方式下咸水的可利用范围，并提出相应的适宜灌溉指标与灌溉制度。以期达到合理高效利用咸水资源，实现土壤环境保护及棉花高产优质的目标。本研究对于指导河北低平原旱地与盐碱荒地开发利用、确保粮食安全、稳定棉花种植面积、以及促进区域社会经济与生态环境可持续发展具有重要的科学意义。

摘要：为合理高效利用河北低平原区浅层地下咸水资源，本项目研究了膜下滴灌方式下不同灌溉水矿化度（1、3、5、7、9 g/L）与不同灌水控制下限（60%田持和70%田持）相组合对土壤水盐变化及棉花生长的影响，模拟了咸水滴灌棉田土壤水盐运移过程，探讨了咸水灌溉棉田土壤质量评价方法，明确了咸水滴灌棉花的灌水指标，并提出了适宜灌溉制度。主要结果如下：（1）阐述了咸水滴灌棉田土壤水盐时空变化规律。棉花生长期间，土壤水分和盐分均呈现随灌溉水矿化度增加而增大的趋势，盐分尤为明显；咸水滴灌棉田同一土层水盐横向分布存在差异，滴灌带下方和覆膜行中心处土壤水盐含量总体上大于裸露行中心；土壤盐分变化量及盐分淋洗率或积盐率可用于表征咸水灌溉棉田土壤盐分平衡状况，与试验开始时相比，试验结束时大于5 g/L灌水处理棉田主要根系层呈现积盐。（2）揭示了棉花生长对咸水滴灌的响应特征。棉花成苗率、地上地下部形态生长指标和籽棉产量随滴灌水矿化度增加均呈现出先增大后减小的趋势，高水分和低水分条件下籽棉产量开始降低时对应的灌溉水矿化度阈值分别为6.2 g/L和7.3 g/L。（3）探明了咸水滴灌棉花耗水规律。不同矿化度咸水滴灌棉花的耗水规律相似，但耗水组成存在差异，棉花全生育期耗水量随灌溉水矿化度的增加先增大后降低，处理间水分利用效率的差异不显著。（4）对HYDRUS-2D模型参数进行了属地化修正，确定了适宜的模拟区域和边界条件，较好的实现了咸水滴灌棉田水盐运移模拟，剖面土壤水分和盐分浓度模拟的平均误差分别控制在了15%和26%以内。（5）明确了咸水滴灌对棉田耕层土壤理化性质的影响效应，提出了土壤质量评价方法，土壤质量有随灌溉水矿化度增加而降低的趋势。综合考虑土壤盐分变化、土壤质量安全及棉花生长响应，推荐河北低平原区咸水膜下滴灌棉花的灌溉水矿化度≤5 g/L，灌水下限为田持的60%，灌水定额为20 mm。研究结果丰富了棉花咸水灌溉技术体系，对于保护农田生态环境、促进区域经济社会发展具有重要意义。