Rational irrigation and nitrogen supply methods improving grain yield and water-nitrogen use efficiency of seed maize

Abstract: Ridge planting-furrow irrigation has been widely used, but information on rational irrigation and nitrogen (N) supply methods under ridge planting-furrow irrigation has received only limited attention. To improve harvest index (HI) and resource use efficiency of crop through different irrigation and N supply methods in arid areas, we carried out field experiments to investigate the effect of different irrigation and N supply methods on HI and water-nitrogen use efficiency of seed maize (Zay mays, Gold northwestern 22) grown in the arid area of northwest China in 2013 and 2014. All experimental ridges were built in a west-east direction. The experiment was comprised of 3 irrigation methods and 3 N supply methods in 2013. The 3 irrigation treatments included alternate furrow irrigation (AI), fixed furrow irrigation (FI) and conventional furrow irrigation (CI). In the CI treatment, all the furrows were irrigated for every irrigation event. In the AI treatment, the 2 neighboring furrows were alternately irrigated during consecutive watering events. In the FI treatment, only 1 (south furrow) of the furrows was irrigated. At each irrigation treatment, the 3 N supply treatments were used and they included alternate N supply (AN), fixed N supply (FN) and conventional N supply (CN). In the CN treatment, N fertilizer was applied to all furrows. In the AN treatment, N fertilizer was alternately applied to 1 of the neighboring 2 furrows in consecutive fertilization. In the FN treatment, N fertilizer was only supplied to 1 of every 2 furrows. Evapotranspiration (ET) during maize grown season, and biomass, grain yield and its components as well as nitrogen uptake at maturity stage of maize were measured. The HI, water use efficiency (WUE) and nitrogen use efficiency (NUE) were calculated. Based on the results of 2013, the fixed treatments (fixed furrow irrigation and fixed nitrogen supply) were excluded in 2014. The results showed that, the grains per row per plant were greatly affected by irrigation and nitrogen supply methods. Thousand seed weight was only influenced by irrigation method. The ET during maize grown season was only influenced by irrigation method, and AI significantly reduced ET compared to the other irrigation methods. The WUE of maize for AN and CN was higher than that for FN in any irrigation method; AI had the highest WUE, followed by CI and FI in any nitrogen supply method. Nitrogen uptake, HI and NUE of maize showed similar results compared to WUE. AI coupled with CN achieved the highest HI, WUE and NUE in 2013, and these increased by 5.46%, 11.41% and 19.73%, respectively if compared with CI coupled with CN. AI coupled with AN (irrigation and N fertilization were conducted within a same furrow) showed a similar result compared to AI coupled with CN. The 2014 experiment verified the above results. Therefore, alternate furrow irrigation coupled with conventional nitrogen supply and alternate furrow irrigation coupled with alternate nitrogen supply (irrigation and N fertilization were conducted within a same furrow) are useful to improve grain yield and water-nitrogen use efficiency of seed maize.