Maintaining rice grain yield under two irrigation regimes while reducing water-nitrogen input using acidified nitrogen-loaded biochar

Qi Wu, Fuzheng Gong, Xiaofeng Jia, Meitao Tan, Wenzhong Zhang and Daocai Chi

Agricultural Water Management, 2023, vol. 287, issue C

Abstract: Excessive water and nitrogen (N) input can lead to environmental problems in irrigated areas. By using acidified N loaded biochar with hydrophilic functional groups, it may be possible to reduce water and N usage in rice fields. Therefore, a two–year pot experiment was conducted in northeast China in 2019 and 2020, using a two–factor randomized block design with two irrigation regimes including alternate wet–dry irrigation (IAWD) and continuous flooding irrigation (ICF) as the first factor. The second factor was combinations of NH4Cl acidified N–loaded biochar (NB) and N reduction including the control (local practice, 100%NC0), 10 t ha−1 or 20 t ha−1 NB and 25% less N fertilizer (75%NC1, 75%NC2), and 10 t ha−1 or 20 t ha−1 NB and 50% less N fertilizer (50%NC1, 50%NC2). The effects of NB on N concentrations in surface water, water consumption, N use and water productivity (WP), yields and its components under different irrigation regimes were studied. Results show that exposed to 25% and 50% less N input, the grain yield of C2 was 2.96% and 3.74% higher than that of C1, respectively (two–year average), indicating that NB treatment improved the stability of yield. Stable effective panicles and increased grains per panicle were the main reasons of NB for stabilization of rice grain yield. Compared to the 100%NC0 treatment, 75%NC1 and 75%NC2 significantly reduced the total water consumption by 9.6% and 10.4%, respectively, across two irrigation regimes. The IAWD reduced water consumption during all growth stages, resulting in an average reduction of total water consumption by 10.5%. As a result, the 75%NC2 treatment (1.26 g kg−1, 64.76 g pot−1) had the highest statistical WP and yield. IAWD resulted in the highest increase in surface water ammonium N for the 75%NC1 and 75%NC2 treatments. Under IAWD, from 59 to 99 days after transplanting, the surface water ammonium N concentrations of 75%NC1 and 75%NC2 were 9.7% and 22.5% higher than that of 100%NC0, respectively. This effect was most evident in the later growth stages, resulting in a 5.9% increase in panicle N accumulation and a 10.7% increase in root N accumulation. In summary, using 75%NC2 combined with IAWD was the most effective way to save irrigation water by 10.4%, reduce N input by 25%, promote N uptake in panicles and roots while maintaining rice yield stability.

Keywords: Water productivity; Nitrogen uptake; Surface Water; Soil amendment; Rice (search for similar items in EconPapers)
Date: 2023
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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:287:y:2023:i:c:s0378377423002974

DOI: 10.1016/j.agwat.2023.108432

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