Soil sorptivity enhancement with crop residue accumulation in semiarid dryland no-till agroecosystems

摘要

Water capture and precipitation use efficiency are of great importance in dryland cropping systems because the world's dependence on food produced in dryland areas continues to increase. Growing season evapotranspiration potential greatly exceeds growing season precipitation rates in dryland areas, creating a water deficit for crops. Management practices that positively impact soil physical properties increase the potential for soils to capture water. One way to assess the ability of soils to capture water is through the measurement of sorptivity. Sorptivity is defined as the cumulative infiltration proportionality constant and is governed by surface soil physical properties such as texture, degree of aggregation and aggregate stability. A study was conducted to determine how crop residue accumulation after 12 years of no-till management affects surface soil sorptivity under semi-arid dryland conditions and how sorptivity is related to surface soil physical properties known to be related to crop residue accumulation. Surface soil sorptivity, bulk density, porosity (total and effective) and aggregation measurements were made across cropping systems and soil positions representing a wide gradient of crop residue accumulation at 3 sites in eastern Colorado. Results show that increasing crop residue accumulation will have the indirect effect of increased sorptivity via improvements in soil aggregation, bulk density, and porosity that are conducive to water infiltration. Management practices that result in greater amounts of crop residue returned to the soil system lead to beneficial soil physical properties that increase water sorptivity, greatly reducing the potential for runoff and erosion, and thereby increase the precipitation use efficiency of the system