Soil Amendments for Improving Soil Chemical Properties and Enhancing Plant Growth in Desertified Soils of Ningxia, China.

Desertification is one of the most serious problems affecting grassland ecosystem health and agricultural production in semi-arid regions globally. In Ningxia, China, thousands of years of agriculture have chronically degraded the soils resulting in 98% sand content with less than 1% organic matter and high pH (9.0). An international team of researchers has been investigating the use of coarse woody amendments to increase soil organic matter content and jumpstart the restoration of degraded grassland soils in Ningxia. Wood chips derived from tree branches of four available tree species (poplar, elm, locust, and grapevine), as well as wheat straw, rice husks and cow manure were incorporated into the top soil layers and compared for their effects on soil physical and chemical properties in a series of replicated microcosm experiments. The results clearly demonstrated that incorporated organic materials reduced evaporation, improved water holding capacity and water storage, and enhanced soil microbial activity and biomass. Both fertilizer and cow manure additions resulted in decreasing pH to nearly neutral levels. Supplementing soils with fertilizer as well as organic matter resulted in an increased total biomass, root development and SPAD of wheat plants. A field experiment was conducted to evaluate similar treatments on growth of native and exotic grass species. After one year of irrigation to allow establishment, the grasses and especially native Achnatherum splendens, were growing successfully with little or no supplemental watering. These results strongly indicate that a recipe of ingredients, including organic matter from selected species and fertilizer, added to soils can successfully improve soil health and support better plant growth in desertified soils.