Effects of nitrogen-contaminated irrigation methods on the growth and development of rice and nitrogen movement through cultivation layers in the Red River Delta, Vietnam

Abstract

The experiment was conducted in the field to evaluate the effect of nitrogen-contaminated irrigation methods on the growth, development, and yield of rice (Oryza sativa L.) and the movement of nitrogen through the cultivation layers. The experiment was arranged in a Randomized Complete Block Design with three replicates. It was conducted in the summer season of 2022 at the rice experiment area of the Faculty of Environment, Vietnam National University of Agriculture, with three treatments, namely: T1 (control; continuous flooding (CF) with clean water), T2 (alternate wetting and drying (AWD) with nitrogen-contaminated water), T3 (CF with nitrogen-contaminated water). Experimental results indicated that different irrigation methods with nitrogen-contaminated water affect the growth, development, and yield of rice and the movement of nitrogen in the cultivated soil layers (at 35 cm depth, 70 cm – depth, 120 cm – depth). T2 treatment was the best irrigation method for reducing the amount of water for irrigation of rice and limiting the amount of excess nitrogen on the arable soil layers, which affects the quality of shallow groundwater. The movement of nitrogen nitrates through shallow groundwater was less than that of ammonium nitrogen form, and there was no difference in nitrogencontaminated irrigation using water-saving (T2) and flooded irrigation (T3) methods and within the safe threshold (QCVN 09-MT:2015/BTNMT).