L. Zhou - College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling ۷۱۲۱۰۰, Shaanxi Province, China.
Hao Feng - Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling ۷۱۲۱۰۰, Shaanxi Province, China.
Y. Zhao - College of Natural Resources and Environment, Northwest A&F University, Yangling ۷۱۲۱۰۰, Shaanxi Province, China.
Zh. Qi - Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling ۷۱۲۱۰۰, Shaanxi Province, China.

Sandy fields have been reclaimed to exploit the grain production potential in northwestChina. A 2-year statistically replicated field study was conducted to determine the effects ofmulched drip irrigation on soil water, soil nitrate, shoot root growth and yields of maize on asandy field in the Hetao irrigation district. Treatments included border irrigation (BI), fullymulched drip irrigation (FMDI) and partially mulched drip irrigation (PMDI). Low frequencyfertigation and high frequency fertigation were applied in 2014 and 2015, respectively. Theresults showed that high frequency mulched drip irrigation (MDI) maintained soil moisture andNO3--N at suitable levels and improved soil water uniformity (Cus). Soil NO3--N was adequatefor the FMDI treatment of both high and low frequency fertigations, but it was insufficient forthe PMDI treatment under low frequency fertigation. Soil water and Cus regulated root-shootvia leaf areas and surface root areas were described well by the ratio of root surface area to leafarea (Sr/l). Higher Cus tended to cause a lower Sr/l. Compared with the BI treatment, a higheryield and harvest index (HI) was obtained under the MDI treatments primarily due to the highnumber of grains per spike. The FMDI and PMDI treatments resulted in no yield differencesunder high frequency fertigation. Therefore, high frequency PMDI management with irrigationamounts based on the reference evapotranspiration after the jointing stage were recommended inthe sandy maize field based on economic considerations. Under low frequency fertigation, theFMDI treatment was recommended for a higher yield, which was attributable to the higher drymatter of the vegetative organs and maintaining higher levels of soil NO3--N in the upper sandlayer when compared to the PMDI treatment.

Soil water uniformity, Harvest index, Mulched drip irrigation, Shoot-root regulation, Sand-layered soil