东北黑土区土壤侵蚀对"作物产量-土壤水分响应关系"的影响

Black soils have high productivity due to its rich organic matter content and made the northeastern China be the commercial crop base area, while soil erosion extended seriously currently in this region. Most cropland are rain fed in this region, so it is very important to understand how the soil erosion to have impacts on crop yields responding to the soil water. This study focuses on the black soils with different erosion degrees. The aims are to understand variations of soil water holding and infiltrating capacities resulted from soil erosion firstly based on the soil physical and chemical feature analyses, to determine the responding functions of crop yields to soil water secondly by potted crops under soil water content control for soils with 3 erosion levels, to conclude the soil water balance and its impacts on crop root growth and distribution in the soil profiles thirdly through the field soil water content and crop growth monitoring, and to validate the functions of crop yields responding to soil water under different soil erosion degree lastly. The study could guide the farmland management and soil conservation planning in addition to supply the cases for farmland soil water budget models and land surface models such as models of crop growth, soil erosion and hydrologic processes. .

东北黑土因富含有机质具有高生产力而成为我国重要的商品粮基地，但土壤侵蚀已对黑土资源构成严重威胁。该区以旱农为主，土壤水分对产量的影响至关重要，弄清土壤侵蚀对土壤水分及作物产量-土壤水分响应关系的影响机理，是进行农田管理、指导水土保持耕作措施规划、进而提高土壤质量及其生产力水平的科学基础。本项目首先通过不同侵蚀程度黑土样品的理化性质分析，研究土壤侵蚀导致的持水和入渗特征变化，及其与土壤理化性质的关系；然后通过不同侵蚀程度黑土的作物盆栽控水实验，揭示这种关系对作物生长过程和产量形成的影响机理与程度，建立侵蚀条件下的作物产量-土壤水分响应函数；最后通过不同侵蚀程度大田土壤水分和作物生长动态及产量监测，阐述侵蚀对农田土壤水分平衡的影响和土壤水分对根系生长及分布的影响，并进行模型验证。研究成果不仅是对农田土壤水分平衡和土壤侵蚀影响土地生产力定量评价的重要补充，而且能为农田水土保持管理提供理论指导。

东北黑土区侵蚀对生产力的影响已成为不争的事实。该地区以旱作农业为主，弄清侵蚀如何影响土壤持水能力，进而如何影响作物产量，是科学实施水土保持耕作措施的重要理论基础。本项目在东北典型黑土区选择不同侵蚀强度土壤，通过分析其土壤持水能力变化，以及盆栽控水试验和大田作物生长监测，揭示了侵蚀对土壤供水和持水能力的影响，建立了作物产量-水分响应关系，并利用大田监测结果和作物生长模型验证了上述关系。主要结果包括：（1）由于黑土黏重，轻到中度侵蚀对土壤持水和供水能力影响不显著，当侵蚀使砂粒含量明显增高后，才使其发生显著改变。改变之前可用VG模型模拟土壤水分特征曲线，之后则不适宜。（2）无论是最优供水还是水分胁迫，轻到中度侵蚀的产量-水分响应关系一致，达到重度侵蚀后，响应关系发生变化。减少相同土壤水分情况下，轻度和中度侵蚀土壤的胁迫系数大于重度侵蚀，即前者对水分的响应较重度更为敏感。（3）大田监测结果表明，侵蚀10cm土壤，导致产量减少约7%。作物模型的模拟结果不仅验证了不同土壤侵蚀强度的作物水分响应关系，也验证了侵蚀导致的产量下降速率。应进一步深入研究侵蚀影响下的水肥协调机制。