Coupling evapotranspiration partitioning with water migration to identify the water consumption characteristics of wheat and maize in an intercropping system

Abstract

Climate change will likely intensify water shortages, so more attention should be given to the efficient use of agricultural water in agricultural production, especially under rainfed conditions. Therefore, studying and understanding crop water consumption amounts and patterns is of great importance. However, the amount of water consumed by the component crops in strip intercropping systems has received little attention. To close this knowledge gap, a two-year field experiment of sole wheat (Triticum aestivum L.), sole maize (Zea mays L.), and wheat/maize strip intercropping was carried out under rainfed conditions. Soil water content, sap flow, soil water evaporation, and evaporation of canopy interception were measured both in intercrops and sole crops. Soil water movement between strips, evapotranspiration components, and water use efficiency were calculated. Compared with corresponding sole crops, intercropping increased water consumption of wheat and maize during the growing period of each crop. Intercropped wheat obtained soil water from the adjacent maize strip during the co-growth period, while intercropped maize obtained soil water from the adjacent wheat strip after wheat harvest. The amount of water obtained by maize was much less than the amount of water obtained by wheat. The transpiration of intercropped wheat was greater than that of sole wheat, but the transpiration of intercropped maize was lower than that of sole maize. Compared with sole cropping, intercropping increased the sap flow rate of wheat in border rows but reduced sap flow rate of maize in border rows, and this phenomenon was pronounced in the case of drought. After wheat harvest, soil water evaporation from the intercropped wheat strip was less than that from sole wheat, and evaporation from the intercropped maize strip was significantly higher than that of sole maize. The two-year average water use efficiency of intercropped wheat was 32% more than that of sole wheat, and water use efficiency of intercropped maize was 10% less than that of sole maize. These results can improve the understanding of water consumption in wheat and maize of intercropping from the point of evapotranspiration partitioning, and provide implications for water management of intercropping system under rainfed conditions.