Effect of Straw Pretreatment on the Soil Water-Holding Capacity and Evaporation in Low-Suction Section

The direct return of straw to soils can lead to problems of slow decomposition, disease and pest occurrence, and nitrogen immobilization by microorganisms competing with crop uptake. In this study, we have examined straw pretreatments (comminution, addition of liquid ammonia and blending with ferric hydroxide) that can be applied before returning it to the soil. We have conducted a laboratory experiment to investigate the effects of these treatments on soil water content, water-holding capacity and soil water characteristic curves. Finely-cut straw (powdery) increased soil saturated water content and improved soil water-holding capacity and water-supplying capacity, while long-cut straw (2 cm long) had smaller effects on these properties and comminuted-ammoniated straw led to a significant increase in these properties. Finely-cut straw and long-cut straw both led to rapid soil dehydration, while for the ammonia-amended straw and straw blended with ferric hydroxide the dehydration rate was lower. The above results provide a basis for the selection of the novel and efficient methods for returning straw to soils.