Sustainable Use of Soil Water Resources and Crop High-Quality Production in Water-Limited Regions

Crop can effectively produce plant productions and services to meet the needs of the people. However, because land use changes alter the plant water relationship, resulting in soil dryness, soil degradation and crop failure in dry years, or waste of soil water resources in wet year in water-scarce areas, both are unfavorable for the sustainable utilization of soil water resources and crops high- quality production. Therefore, it is necessary to adjust the unbalanced plant water relationship, obtain the maximum yield and services to realize the sustainable utilization of soil water resources by plants and crops high-quality management. However, there is not a universally accepted theory to provide guidance of regulation of plant water relationship in practice. Here we show that the theory of sustainable use of soil water resources includes the Soil Water Resources Use Limit by Plants (SWRULP) and Soil Water Vegetation Carrying Capacity (SWVCC). The SWRULP is the soil water resources in the Maximum Infiltration Depth (MID) in which the soil water content in every soil layer equal to wilting coefficient. The wilting coefficient is expressed by the wilting coefficient of indicate plant in the community. When soil water resources in the MID is lower than SWRULP, the plant water relation enters the Critical Period of Plant Soil Relationship Regulation (CPPSRR). The day on which the soil water resources in the MID is lower than SWRULP belong to soil water resources shortage period. If present plant density is more than SWCCV in the critical period of plant soil relationship regulation, plant soil relationship regulation has to be regulated based on SWCCV and then realize sustainable use of soil water resources and get the maximum yield and service. SWVCC is the population or density of indicator plants in a plant community when the soil water supply is equal to soil water consumption in the root zone in the CPPSRR, which changes with plant community type, site condition and time.