土壤-地膜-植物-大气系统水热传输机理及其与作物生长的耦合模拟

Plastic film mulching has been widely used in the arid region of Northwest China, due to its distinctive effect on increasing temperature and retaining moisture of the soil. Study on the energy distribution and water/heat transfer mechanism in the soil-mulch-plant-atmosphere system (SMPAS), as well as their interactions with the crop growth, is significant to the high efficient utilization of agricultural water resources, the prevention of soil salinization, the improvement of soil microorganism environment and the control of greenhouse gas emission. .Batch experiments will be conducted to study the influence of the main control factors of field mulching, e.g., the optical property of the mulch, the thickness of the gap between the mulch and the ground surface, the mulch ratio or the area of opening holes etc., on the water/heat flux through the ground surface. Soil column experiment will be conducted to investigate the water/heat transfer with alternate evaporation and infiltration under typical mulching methods. Field experiment will be conducted to monitor the water/heat transfer in SMPAC and the crop growth under field mulching/without mulch and various irrigation treatments for typical crops. Based on the statistical analysis of the experimental data, targeting simulation examination and scenario predictions, the parameters among the main processes will be quantified. Then the coupled model of water/heat transfer in SMPAS and the crop growth will be established. The research aims at quantifying the effect of main control factors of field mulching on the ground net radiation, surface water/heat flux and water/heat dynamics inside the soil, as well as understanding the coupled influence of mulching and water saving irrigation on the water/heat transfer in SPAC and the crop growth and yield, so as to obtain the optimum mode with both field mulching and water saving irrigation benefiting the high efficient utilization of agricultural water resources.

地膜覆盖具有明显增温保墒作用，广泛应用于我国西北旱区农业。研究土壤-地膜-植物-大气系统（SMPAS）的能量分配和水热传输机理及其与作物生长的耦合模拟对农业水资源高效利用、防治土壤次生盐碱化、改善土壤微生物环境和控制温室气体排放具有重要意义。本研究拟进行覆膜控制因子（薄膜光学特性、薄膜与地面间隙厚度、覆膜面积等）对地面水热通量影响的批量试验和典型覆膜方式入渗蒸发过程中土壤水热动态试验，并进行典型作物农田覆膜/不覆膜和不同灌水处理下的土壤、冠层水热传输和作物生长监测。通过机理分析、统计回归、针对性的模拟验证和情景预测量化主要过程参数，进而建立SMPAS水热传输和作物生长耦合模拟模型。旨在探索覆膜控制因子对地面能量分配、地表水热通量及土壤水热动态的影响机理，明晰覆膜和节水灌溉联合作用对农田SPAC水热传输和作物产量的影响规律，探索促进农业水资源高效利用的农田覆膜和灌溉制度综合优化方案。

地膜覆盖具有明显增温保墒作用，广泛应用于我国西北旱区农业。研究土壤-地膜-植物-大气系统（SMPAS）的能量分配和水热传输机理及其与作物生长的耦合模拟对农业水资源高效利用具有重要意义。本项目通过土柱试验和田间试验，结合理论分析和模型模拟，研究了不同覆膜控制因子对地面水热通量的影响，并探究了制种玉米农田覆膜和灌水量对农田水热动态与作物生长的影响，主要成果体现在：（1）覆膜减少土壤蒸发，增加生育前期土壤温度，加快生育进程，促进作物生长，提高作物产量和水分利用效率。（2）基于覆膜对土壤蒸发、降雨截留、土壤温度和作物生长发育阶段的影响构建覆膜条件下的AquaCrop、SWAP、CropSPAC模型。在构建的覆膜条件下CropSPAC模型中，考虑了地膜对净辐射收支与能量分配过程、地面与大气之间显热交换和潜热消耗的影响。（3）覆膜条件下AquaCrop、SWAP、CropSPAC模型对土壤水热动态与作物生长模拟效果均较好。相比AquaCrop和SWAP模型，CropSPAC模型模拟效果最好，适用性最广泛。（4）在西北旱区制种玉米田，适宜采用覆盖比例为60%-80%的透明膜覆盖土壤，生育期内适宜的灌溉制度可设置为：7-10d的灌水间隔，70%的作物需水量作为灌水定额。此研究成果可丰富地膜覆盖下SMPAC水热传输与作物生长的耦合作用的理论研究，为农业节水提供科学指导。