间套作农田土壤水分运移和作物生长模型构建

Crop growth, water and nutrient use under different soil, climate, and water fertilizer managements can be accurately evaluated and predicted by soil-plant system model which had greatly benefit for food security and environment protection. However, Most of these models were developed in abroad. Because some special soil-crop processes and agriculture management with regional characteristic were not considered in these models, the model applicability was restricted and model simulation accuracy was declined in China. Thus it was necessary to develop a new model which based on the regional characteristic in China. Intercropping system is widely utilized in China as the cultivation practice. The major resources are distributed as strips among crop bands (e. g. radiation, temperature, water and nutrition). The intercropping soil-crop system model can also be used in the agriculture managements with band style such as band plastic film covering and irrigation. With the help of science foundation, the effect mechanism of crop canopy and root characteristic on solar radiation and soil water distribution in intercropping system would be investigated through the field trial. A soil water movement and crop growth model in intercropping system would be created, and the model would be parameterized and evaluated by experimental data. This model also was a good base for the development of a soil-crop system model satisfied for regional requirement in our country.

土壤-作物系统模型能够对不同土壤条件，气候因素，水肥管理等因素综合下的作物生长和水肥利用进行评价和预测，对农业生产和环境保护具有重要意义。然而目前常用模型大多源自于国外，众多具有我国区域特点的土壤过程和生产管理方式并未包含在模型框架中，从而限制了模型的使用和模拟精度。因此构建一个自主拥有源代码并契合实际需求的土壤-作物系统模型在我国科研和生产上都有重要意义。间套作是我国一种常见的种植模式，该模式光热水肥资源存在条带状的分配差异，因此以间套作为基础构建土壤-作物系统模型还可以进一步运用到一系列带状农田管理方式中，譬如条带覆膜，灌溉等技术。本基金将通过试验明确间套作条件下作物冠层和根系差异对太阳辐射分配和水分运移的动力学影响机制，并建立间套作土壤水分运移和作物生长模型框架，通过试验数据对模型的适用性进行论证。同时为今后将该模型进一步完善成适宜我国特征区域的土壤-作物系统模型奠定基础。

土壤-作物系统模型在农业生产和环境保护中应用广泛。构建一个自主拥有源代码并契合我国实际需求的土壤-作物系统模型在我国科研和生产上都有重要意义。本项目以我国广泛分布的玉米-大豆间作模式为切入点，设置了不同条带宽幅的玉米大豆间作以及作物单作试验处理，监测了作物种植区域对应土壤剖面水分动态，玉米-大豆间作体系辐射分布，以及作物生长和产量特征。同时完成了间套作土壤水分运移和作物生长模型程序源代码开发、参数本地优化以及模型的初步评价工作。重要结果如下：1）玉米-大豆间作模式对应的土地当量产出要显著高于全田玉米和大豆处理。2）间套作处理相比全田作物处理并没有显著提高光合有效辐射截获比例，玉米截获了更多的辐射同时大豆接受的辐射量降低。3）玉米-大豆间作模式下玉米和大豆种植区域对应的土壤水分动态没有出现显著性的差异。4）项目构建的间套作土壤作物系统模型共设置了水分入渗，水分平衡，光分配，作物生长四个模块。其中在光分配模块中的光合有效辐射分配采用几何机理模型进行描述，相比传统模型有大幅度提升，该模块能对不同条带带宽下的间套作模式的辐射分配进行准确地模拟，增强了模型的适用性。5）系统模型对于玉米大豆产量的预测值与实测值比较对应RMSE为461 kg ha-1，模型预测精度较高，同时偏差较小。6）运用该系统模型对一系列玉米和大豆条带宽幅组合的间作模式进行产量预测，预测结果认为在研究区具有最高当量土地产出的玉米-大豆间套作模式为1行玉米3行大豆，考虑机械化条件下，4行玉米6行大豆间作是最佳的种植方式。本项目开发的模型和本地化的参数适用于我国间作模式下的土壤水分过程和作物生长和产量模拟预测，是未来间套作生长相关研究的有益科学工具，同时也为未来开发适用于更多我国特有农业模式的土壤-作物系统模型奠定了很好的基础。