Nitrogen loss via runoff and leaching from paddy fields with the proportion of controlled-release urea and conventional urea rates under alternate wetting and drying irrigation.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023;
30:61741-61752. [PMID:
36934189 DOI:
10.1007/s11356-023-26480-w]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/12/2023] [Indexed: 05/10/2023]
Abstract
Alternate wetting and drying irrigation (AWD) can reduce non-point source pollution from paddy fields by mitigating field water depth. However, the influence of compounding modes of polymer-coated urea (PCU) and conventional urea (CU) on nitrogen (N) loss via runoff and leaching from paddy fields under AWD conditions remains unclear. To address this question, in this study, a 2-year field experiment was set up with three N management treatments: (a) 100% CU (N1), (b) 60% PCU + 40% CU (N2), and (c) 100% PCU (N3), at an equivalent N rate of 240 kg ha-1 that was applied to traditional continuously flooded (CI) and AWD systems. The results of this experiment showed a high-risk period of N loss from the paddy fields within 7 d after basal fertilization and 5 days after tillering fertilization. AWD reduced irrigation frequencies by 3.5 times and total input of irrigation water by 38.1%, increasing water utilization from precipitation by 44.4% than CI and reducing the volume of runoff by 46.1% and leaching water by 22.1%. This reduced the total N (TN) loss through runoff and leaching under AWD. In the N2 and N3 treatment groups, N concentration in floodwater decreased from 33.8 to 24.9%, TN loss via runoff decreased by 35.3 to 25.0%, and leaching decreased by 41.7 to 30.3% from the paddy field compared to N1. With the same N mode, AWD showed a higher N uptake (from jointing to maturity stage) and rice yield compared to CI. Besides, N2 and N3 had higher N uptake compared to N1 under the two irrigation regimes. Moreover, the AWDN3 and AWDN2 treatments resulted in the lowest and second-lowest loss of TN via runoff (2.21 to 2.66 kg ha-1) and leaching (8.14 and 10.21 kg ha-1), respectively, from the paddy fields and had the relatively high N uptake in rice in the maturity stage. Remarkably, compared with N3, N2 had a comparable grain yield under CI; however, it showed a higher yield under AWD, suggesting that there is a positive interaction in the rice yield between the AWD and compounding N (PCU + CU) fertilization practice. Thus, AWD coupled with N2 could be recommended as a useful approach to reduce N loss via runoff and leaching from paddy fields, which could increase the grain yield of middle-season rice.
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