Root characteristics, utilization of water and nitrogen, and yield of maize under biodegradable film mulching and nitrogen application

Abstract

The biodegradable film is an alternative to polyethylene film due to polyethylene residue pollution, but whether the biodegradable film can replace polyethylene film in terms of root growth, utilization of water and nitrogen, yield, and reducing N application remains unclear. Therefore, two-year field trials, involved two films (biodegradable film and polyethylene film) as the main plots and four nitrogen levels (0 (N0), 90 (N1), 180 (N2), and 270 (N3) kg N ha–1) as the subplots, were conducted. The results showed that compared with N0, N application significantly increased root length density (0–20 cm layer), root surface area density (0–10 cm layer), root weight (0–10 cm layer), and root/shoot ratio by 41.6%, 38.8%, 89.8%, and 33.0% on average for biodegradable film and by 40.3%, 33.9%, 61.5%, and 23.3% for polyethylene film, respectively. However, N application only significantly increased the root-bleeding sap per unit area (RBS) by 20.1% for biodegradable film compared to N0. Furthermore, N-fertilization significantly increased shoot dry matter, evapotranspiration (ET), water use efficiency (WUE), nitrogen use efficiency (NUE) (except for N3), and yield by an average of 31.8%, 9.5%, 33.2%, 7.9%, and 46.1% (biodegradable film), 24.8%, 11.6%, 34.4%, 7.5%, and 50.3% (polyethylene film), respectively, compared with N0. Compared with polyethylene film, root length densities, root surface area densities, root weights in the 0–10 cm layer, and WUE were significantly lower, but RBS (except for N0), ET, and NUE were significantly higher under biodegradable film. Path analysis showed that both improving root length density and root weight were conducive to increasing dry matter accumulation, WUE, and yield for two films. The optimum N rate was also found at 173.2 kg ha−1 for biodegradable film and 182.1 kg ha−1 for polyethylene film, which could increase NUE. Therefore, ridge-furrow with biodegradable film mulching combined with 173.2 kg N ha−1 could achieve the goal of replacing polyethylene film in terms of high yield, efficient utilization of nitrogen, and reducing N application.