Recipes for Restoring Desertified Agricultural Grasslands - Successes and Challenges.

Grasslands formerly occupied one third of the earth’s land surface, the natural biome adapted to a semi-arid climate which receives less than 600 mm of rainfall annually. Over millennia, grasslands have been almost universally impacted by agricultural practices including vegetation clearing, tillage and livestock overgrazing, which have resulted in chronic erosion, soil health degradation and desertification. There is an urgent need to restore these grassland ecosystems, and particularly the soil organic matter which provided a critical mechanism for capturing and storing scarce rainfall. For the past five years, an international team of researchers has been investigating strategies for jumpstarting the restoration of desertified grassland soils in the Yellow River Valley of Ningxia, China. Microcosm experiments and field plot studies clearly demonstrate that amendments of coarse wood chips in the top soil layers provide a mechanism for capturing more rainfall and maintaining higher soil moisture contents between infrequent rain events. These benefits can be enhanced via an aboveground branch lattice which shades and cools the soil. Our studies further indicate that natural grass canopies efficiently reduce overall evaporative losses and capture night-time condensation, providing an alternative water source. When supplemented with fertilizer, the amended soils supported significantly increased wheat production and sustainable grass growth with reduced irrigation demand. Our approach has been tested successfully in soils at the Northern Great Plains Research Lab in Mandan, North Dakota. This 2016 SSSA Special Session is being held to overview the research results and to develop a network of researchers interested in testing and tailoring the methodology elsewhere in the Great Plains and globally.