Impact of different water and nutrient supply strategies by fertigation on corn yield and yield components in subsurface drip irrigation

In recent years, the use of subsurface drip irrigation has increased in row crops because of its high water and fertilizer use efficiencies. In the present study, the effects of different irrigation and fertilization treatments on corn grain yield, yield components, water efficiency and soil residual nitrate content (SRNC) were investigated. A 2-year field split-split-plot study was conducted on a randomized complete block design with three replications in the research field of Urmia University, Iran. The main treatment of this experiment consisted of three irrigation levels, including full irrigation (FI), 75 (DI75) and 50% (DI50) of the corn's net water requirement and sub-treatments, including three different nitrogen (N) application frequencies (weekly (S1), once time every 2 weeks (S2) and three applications (S3)) and two fertilizer injection times. The effects of irrigation levels and N application frequency were significant on grain yield, dry matter and water productivity at 0.01 and 0.05 significance levels, respectively. The highest water productivity was observed in DI75 with values of 3.02 and 3.11 kg m-3 for the 2018 and 2019 growing seasons, respectively. The SRNC was affected by irrigation and fertilization treatments at 0.01 significance level. The highest and lowest SRNCs were measured in DI50 and FI, respectively. According to the results, applying DI75 can save water with no significant reduction in crop yield. Also, N application in three splits can provide sufficient N and decrease SRNC, which prevents N losses to groundwater resources.