单作与间作的棵间蒸发量差异及其主要影响因子

在甘肃河西走廊区, 通过大田试验, 研究了不同供水水平下小麦间作玉米与单作小麦、单作玉米的耗水量和棵间蒸发量差异, 探讨了影响作物棵间蒸发量的关键因子。结果表明, 小麦间作玉米的耗水量较单作小麦、单作玉米耗水量的平均值增加了41.44%~47.15%; 间作全生育期的总棵间蒸发量显著大于单作, 但间作的日均棵间蒸发量显著低于单作玉米、高于单作小麦; 间作的棵间蒸发量占总耗水量的比重显著低于单作玉米, 说明间作可提高农田水分利用的有效性。随灌水水平的提高，间作总耗水量显著增加，单作相邻灌水处理间的差异不显著；灌水水平对单作玉米、间作棵间蒸发量的影响不显著，说明间作耗水量增加主要是由蒸腾作用造成的。作物的日均棵间蒸发量与0~30 cm的土壤含水量、0~25 cm的土壤温度、全生育期的平均叶面积指数均呈显著正相关关系。单作玉米日均棵间蒸发量较大的主要原因是0~30 cm的土壤含水量、0~25 cm的土壤温度均相对较高。小麦间作玉米可提高作物的土地利用率, 其水分利用效率较单作平均提高25%以上。

Soil evaporation under sole cropping and intercropping systems and the main driving factors

Several studies have shown that compared to sole cropping, well managed intercropping improves agricultural resources utilization efficiency, include radiation, nutrient, water and land. However, high productivity of traditional intercropping system has mainly depended on high input of agricultural resources. With severe water shortages in recent years (especially in mainland China), intercropping system of farming has continuously declined. The scientific challenge therefore is the determination of water consumption characteristics and systematic development of high-efficiency water-saving theories and technologies of intercropping system. In this study, a field experiment (comprising of wheat or maize sole cropping and wheat-maize intercropping systems under three different irrigation schemes) was conducted in 2008 in the Hexi Corridor oasis region. The study investigated soil evaporation characteristics and associated driving factors under the different cropping systems and treatments with the aim of laying the scientific basis for developing optimized irrigation techniques. The study showed that evapotranspiration (ET) under wheat-maize intercropping was 41.44%~47.15% higher than the average ET under wheat and maize sole cropping systems. Total soil evaporation (E) of intercropping system was significantly higher than that of sole cropping systems. However, daily E of intercropping system was significantly lower than that of maize sole cropping system. Also compared with sole cropping system of maize, wheat-maize intercropping system enhanced E/ET ratio. With increasing irrigation, total water consumption increased significantly under intercropping. However, the difference in water consumption between two adjacent irrigation treatments under sole cropping systems of wheat and maize was insignificant. The difference in E of sole cropping maize and intercropping wheat-maize was insignificant for different irrigation schemes. It then implied that high water consumption of intercropping system was mainly driven by high transpiration. Average daily E was positively correlated with water content in the 0~30 cm soil profile, temperature in the 0~25 cm soil profiles and average leaf area index of the crops. High E was driven by high water content in the 0~30 cm soil profile and temperature in the 0~25 cm soil profile of maize sole cropping system. On the average, wheat-maize intercropping not only reduced water consumption but also increased water and land use efficiency compared to sole cropping. This cut down wasteful crop transpiration, which was an effective means of water-saving irrigation.