Improving water resilience with more perennially based agriculture

摘要

Land conversion from natural to managed ecosystems, while necessary for food production, continues to occur at high rates with significant water impacts. Further, increased rainfall variability exposes agricultural systems to impacts from flood and drought events. In many regions, water limitations are overcome through technological approaches such as irrigation and tile drainage, which may not be sustainable in the long term. A more sustainable approach to combat episodes of floods and droughts is to increase soil water storage and the overall green water efficiency of agroecosystems. Agricultural practices that promote continuous living cover, such as perennial grasses, agroforestry and cover crops, can improve water management relative to annual crop systems. Such practices ensure living roots in agricultural systems throughout the year and offer an approach to agroecosystem design that mimics ecological dynamics of native perennial vegetation. We review how these practices have been shown to improve elements of the water balance in a range of environments, with an emphasis on increased soil hydrologic function. A specific focus on the agriculturally intensive state of Iowa provides insight into how land use centered on agroecological principles affords greater water resilience, for individual farms as well as for broader community and ecosystem health.