Soil Management Practice Effect on Water Balance of a Dryland Soil during Fallow Period on the Loess Plateau of China

Abstract

To understand the mechanisms affecting water balance partitioning during fallow on drylands could improve the fallow management practices in arable land ecosystems. A three-year field experiment was conducted to evaluate the effects of field management regimes on water balance partitioning and fallow efficiency during the fallow periods under a winter wheat (Triticum aestivum L.) fallow system on the Loess Plateau, China. The fallow management regimes tested were: (i) conventional practice, (ii) catch cropping, and (iii) no tillage with wheat straw mulching. A process-oriented ecosystem model (CoupModel) was calibrated with field measurements and then used to generate comparative simulations of the water balance partitioning. The simulations indicated that mulching increased the soil water storage change by 3871 mm during the three fallow periods, thus resulting in higher fallow efficiency by 912%, and decreased soil evaporation by 2272 mm, compared with the conventional practice. Furthermore, water reached deeper horizons, resulting in 7 mm deep percolation in a wet year under mulching but not under conventional practice or catch cropping. The simulation results also showed that the catch cropping decreased the soil water storage change by 1321 mm, although it lowered soil evaporation by 1151 mm, and altogether reduced the fallow efficiency by 39%, compared to conventional practice. On the Loess Plateau of China mulching proved to be a sound measure for ensuring certain fallow efficiency and possibly benefit to the water cycle, while catch cropping negatively partitioned the water balance. The catch cropping under mulching might be another management regime to be considered.