Effect of sprinkler irrigation on microclimate in the winter wheat field in the North China Plain

Sprinkler irrigation, as one of the useful technologies to increase crop production and water use efficiency, has been extensively used in the North China Plain. However, few researches related to the season-long microclimatic changes under sprinkler irrigation in this region. A field experiment was carried out to investigate the long-time effect of sprinkler irrigation on microclimate in a winter wheat (Triticum aestivum L.) field and compare the microclimate under both sprinkler and surface irrigation conditions from April 2001 to June 2003 in two experimental stations in the North China Plain. Results showed that air temperature, air temperature gradient from 1 to 2 in above ground surface and vapor pressure deficit (VPD) were significant lower (P < 0.05) in the sprinkler-irrigated field with respect to those in surface irrigation field after the first sprinkler irrigation during three winter wheat seasons. The maximum reduction in air temperature and VPD in the sprinkler-irrigated field in comparison with the surface irrigated field occurred on sprinkler irrigation days. During daytime (between 08:00 and 20:00 h), air temperature and VPD were significantly affected by sprinkler irrigation respected to night-time (between 20:00 and 08:00 h) at sprinkler irrigation intervals. Cumulative water surface evaporation, measured by using a standard pan (20 cm in diameter) placed at the top of canopy, was about 3-11% lower in the sprinkler-irrigated field respected to in the surface irrigated field from April 11 to June 4 in the three seasons. The reduction in values of difference in air temperature, vapor pressure deficit and pan evaporation in the sprinkler-irrigated field in comparison with surface irrigated field were bigger when it was hot, dry and windy with concentrated precipitation. (c) 2006 Elsevier B.V. All rights reserved.