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Chinese Journal of Applied Ecology ›› 2023, Vol. 34 ›› Issue (4): 993-1001.doi: 10.13287/j.1001-9332.202304.009

• Original Articles • Previous Articles     Next Articles

Effects of N fertilizer reduction combined with straw biochar application on the yield, Si, and N nutrition of double-cropping rice

NING Chuanchuan1,2,3, CHEN Yuegui1,2,3, LIU Rui1,2,3, LI Tongxin1,2,3, CHEN Hailang1,2,3, TIAN Jihui1,2,3, CAI Kunzheng1,2,3*   

  1. 1College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China;
    2Ministry of Agriculture and Rural Affairs Key Laboratory of Tropical Agro-Environment, South China Agricultural University, Guangzhou 510642, China;
    3Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, South China Agricultural University, Guangzhou 510642, China
  • Received:2022-09-13 Accepted:2023-02-16 Online:2023-04-15 Published:2023-10-15

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Abstract: Nitrogen (N) and silicon (Si) are important nutritional elements for rice. However, excessive N fertili-zer application and the ignorance of Si fertilizer are common in practice. Straw biochar is rich in Si, which can be used as a potential Si fertilizer. In this study, we conducted a consecutive 3-year field experiment to explore the effects of N fertilizer reduction combined with straw biochar application on rice yield, Si and N nutrition. There were five treatments: conventional N application (180 kg·hm-2, N100), 20% N reduction (N80), 20% N reduction with 15 t·hm-2 biochar (N80+BC), 40% N reduction (N60), and 40% N reduction with 15 t·hm-2 biochar (N60+BC). The results showed that compared with N100, 20% N reduction did not affect the accumulation of Si and N in rice; 40% N reduction reduced foliar N absorption, but significantly increased foliar Si concentration by 14.0%-18.8%; while combined application of biochar significantly increased foliar Si accumulation, with an increase of Si concentration by 38.0%-63.3% and Si absorption by 32.3%-49.9%, but further reduced foliar N concentration. There was a significant negative correlation between Si and N concentration in mature rice leaves, but no correlation between Si and N absorption. Compared with N100, N reduction or combined application of biochar did not affect soil ammonium N and nitrate N, but increased soil pH. Nitrogen reduction combined application of biochar significantly increased soil organic matter by 28.8%-41.9% and available Si content by 21.1%-26.9%, with a significant positive correlation between them. Compared with N100, 40% N reduction reduced rice yield and grain setting rate, while 20% N reduction and combined application of biochar did not influence rice yield and yield components. In summary, appropriate N reduction and combined with straw biochar can not only reduce N fertilizer input, but also improve soil fertility and Si supply, which is a promising fertilization method in double-cropping rice fields.

Key words: nitrogen reduction, straw biochar, rice yield, silicon, nitrogen