Abstract

The experiment was undertaken in order to investigate the effect of soil matric potential (SMP) on wolfberry yield, evapotranspiration (ET), water use efficiency (WUE) and the implications for soil water management under drip irrigation in the Yinchuan Plain arid region of Northwest China. The experiment consisted of five treatments, which maintained SMP at a depth of 0.2 m immediately under a drip emitter releasing water at -10 (S1), -20 (S2), -30 (S3), -40 (S4) and -50 kPa (S5), respectively, after wolfberry had been planted. The results showed that during the growing season, the target SMP value of the five different treatments was maintained within the experimental design range and the irrigation volume and ET declined as the target SMP value decreased. The temporal and spatial soil water content (SWC) changes observed in the soil profile suggested that the S1 and S2 treatments could meet the crop water absorption demand because the soil moisture was over 15 % and soil water was in excess of crop needs. However, the soil water content for S3, S4 and S5 was less than 15 %, which produced visible water stress in the crop. Statistical analysis for the change values in the electrical conductivity of the saturated soil-paste extract (ECe) showed the significant differences between the different SMP treatments in the middle layer (40 – 80 cm) and the plots S2 (-20 kPa) had the better effect of the soil salinity leached. The highest yield was achieved in the S2 plots and the lowest fresh to dry weight ratio was found in the S3 plots, which also produced the highest quality seed. WUE was in the order S3 > S5 > S2 > S4 > S1. Based on a comprehensive analysis that included irrigation volume, ET value, crop yield and WUE, it is recommended that the SMP threshold should be controlled in the range from -20 to -30 kPa, which was the most favorable drip irrigation schedule for increasing yields and irrigation efficiency. The study should provide information that could be used in other regions suffering from drought and water scarcity.

Key words: Deep percolation, irrigation volume, soil salinity, soil water content (SWC), vacuum tensiometers.