The Application of Soil Water Characteristic Curve in Determination of Lower Limit of Suitable Soil Moisture in Crop Non-sufficient Irrigation

Water always flows from higher water potential to the lower one in SPAC system.And water potential is the main element that influences the plant water uptake rate.Compared with the soil water content,it will be much more scientific to use the soil water potential as the lowest limit index of crop non-sufficient irrigation and be easier to be applied and extended.The experimental results show that-200 kPa is a more suitable lower limit of soil water potential to the tomato in greenhouse.During application of the above index,the soil water characteristic curve must be determined and then find out the corresponding soil water content of the water potential.Finally through controlling of soil water content to control the soil water potential and then realizes precise irrigation.