文摘
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Summary
Understanding all components of the water balance, especially temporal rainfall patterns, is essential to optimize water use in rain-fed agriculture area. The effect of temporal rainfall patterns on water balance, evapotranspiration (ET), and crop growth was evaluated by considering root water extraction of plants in a rain-fed maize field. Soil water contents at depths of 15, 30, 60, and 90 cm were measured daily in 2-year growth seasons. A soil water balance approach was applied to estimate changes in daily soil water storage. For the detailed water partitioning of the water balance and root water extraction, the soil-water-atmosphere-plant (SWAP) model with water and crop modules was applied. Results suggested that the main depths of root water uptake occurred in the top 60 cm soil layer. Crop transpiration (T) can reach a level above 40 % of the total water consumption during all growth stages, and its reduction was mainly due to the dry condition of soil. The crop yield in 2010 was 1125 kg ha?1 higher than that in 2011, although the rainfall amount in that year was 132 mm less than the rainfall amount in 2011. The water use efficiency (WUE) was also higher in 2010. Therefore, the influence of temporal rainfall patterns was clearly more important than rainfall amounts (water partitioning into evaporation (E), T, and soil water content). Growing season T/ET can be a potential parameter for maize productivity. The field can be irrigated at pivotal growth stages under dry conditions to obtain the optimal effect in improving WUE and increasing grain yield. The SWAP model was a useful tool to analyze water partitioning in the freeze-thaw zone.
