Achieving sustainable rice production through nitrogen-potassium harmony for enhanced economic and environmental gains
Jun Deng, Ke Liu, Xin Xiong, Tajamul Hussain, Liying Huang, Peter de Voil, Matthew Tom Harrison, Xiaohai Tian, Yunbo Zhang
Abstract
In the quest for sustainable, high-yield crop production, achieving the optimal balance between nitrogen (N) and potassium (K) stands as a pivotal goal. We carried out a 3-year field experiment to evaluate the impacts of the combined application of three N rates (90, 120,180 kg N ha−1) and three K rates (120, 160, 210 kg K2O ha−1) on rice yield, fertilizer use efficiency, greenhouse gas (GHG) emissions, global warming potential (GWP), GHG intensity (GHGI), and net ecosystem economic benefits (NEEB) in rice paddy. Our results showed that increasing K under the same N treatment proves beneficial for yield gains (average increase of 4.8 %). Such beneficial effect is also reflected in different N treatments, evidenced by the comparable grain yields between N120 × K160 (9.1 t ha−1) and N180×K120 (9.2 t ha−1). Increasing K significantly enhanced N use efficiency (NUE) through the stimulation of NR, GS/GOGAT, and GDH enzyme activities. This enhancement, along with the strengthened radiation use efficiency (4.7 %), contributed to an overall improvement in grain yield. Compared with N180×K120, both rice varieties, under N120×K160 treatment, showed higher NUE with a 47.6 % increase in PFPN, 12.1 % in NHI, 7.6 % in NUEg, and 9.5 % in NUEb, respectively. Higher NUE also reduced GHGI and improved NEEB. Compared with N180 ×K120 treatment, the GWP and GHGI under N120×K160 treatment decreased by 32.7 % and 31.0 %, while the NEEB increased by $31 ha−1. The composite sustainability scores suggested that the N120×K160 treatment was generally more sustainable compared with other treatments. These findings underscore the significance of optimizing N and K application ratios in rice paddy cultivation, not only for maximizing yields and nutrient use efficiency but also for reducing greenhouse gas emissions and enhancing economic sustainability, ultimately promoting a more environmentally and economically responsible approach to rice farming.