Hydraulic lift: processes, methods, and practical implications for society

Soil water is an essential factor in soil–water–plant studies and larger-scale hydrological investigations. It is considered more critical than other factors that limit plant growth and also affects many fundamental biophysical processes. New strategies are needed to overcome drought and to maintain environmental sustainability. Hydraulic lift (HL) or hydraulic redistribution (HR) processes are one of these strategies found in soil–plant systems, but their effects on crop production and the environment have not been well documented. This article reviews (1) the process of HL, (2) methods showing evidence of HL using soil water potential (Ψs) and sap flow techniques, (3) hydraulically-lifting plants, and (4) practical implications for society. The HL is whereby soil water may be transported upward by deep roots of trees and grasses from the moist region (subsurface) to dry region (surface) at night. Thus, HL provides water to areas planted to shallow rooted plants at the upper soil layers. The HL of water by roots from wet to dry soil layers is a potential approach for better use of water resources for crop/grass growth. Also, increases in soil water by HL improve root growth and function which include soil carbon decomposition or nutrient mineralization rates, and this can probably be associated in nutrient cycling. Another benefit is that mycorrhizal fungi play a relevant role in HL and in the redistribution of this water among plants. Thus, HL provides many soil, agricultural, and environmental benefits.