Response of nitrogen use efficiency and soil nitrate dynamics to soil mulching in dryland maize (Zea mays L.) fields

Abstract

Plastic film (FM) and gravel mulching (GM) have been used extensively to increase dryland agricultural productivity. Understanding mulching effects on nitrogen (N) use efficiency (NUE) and soil nitrogen dynamics is important for optimizing N management strategies. A 3-year field experiment was performed on the Loess Plateau of China to investigate the GM and FM effects on plant N accumulation, N translocation, N harvest index (NHI), NUE and soil NO₃⁻-N dynamics in dryland maize fields. Compared with the control (CK, non-mulching), the mulching treatments markedly promoted plant N accumulation and especially maintained higher N uptake rates during the post-silking stage. At harvest, the total N accumulation was 12.8–41.2 and 33.2–55.8 % higher in the GM and FM treatments, respectively, than in the CK treatment. The NHIs of the mulching treatments were significantly higher by 9.6–32.4 % than the CK treatment, primarily due to greater N translocation and N accumulation post-silking. Overall, compared with the CK treatment, the GM and FM NUEs increased significantly by 17.1 and 28.3 % in 2010, 70.3 and 87.6 % in 2011, and 16.7 and 38.2 % in 2012, respectively. In the wet years of 2010 and 2011, the increased amount of soil NO₃⁻-N in the 100–200 cm layer after harvest was 27.1–57.1 and 47.9–85.7 % lower in the GM and FM treatments, respectively, than in the CK treatment, indicating a lower NO₃⁻-N leaching loss. These results suggest that mulching (especially FM) is an effective measure for increasing NUE and grain yield and decreasing N leaching loss in dry farmland.