Biochar and Nitrogen Fertilizer Promote Alfalfa Yield by Regulating Root Development, Osmoregulatory Substances and Improve Soil Physicochemical Properties

Jinlong Chai, Hang Yang, Zhen Chen, Weifang Li, Dongqing Li and Xiaojun Yu ()
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Jinlong Chai: College of Grassland Science, Gansu Agricultural University, Lanzhou 730070, China
Hang Yang: College of Grassland Science, Gansu Agricultural University, Lanzhou 730070, China
Zhen Chen: Key Laboratory of Cultivated Land Conservation Technology, Ministry of Agriculture and Rural Affairs, Gansu Yasheng Agricultural Research Institute, Co., Ltd., Lanzhou 730010, China
Weifang Li: Key Laboratory of Cultivated Land Conservation Technology, Ministry of Agriculture and Rural Affairs, Gansu Yasheng Agricultural Research Institute, Co., Ltd., Lanzhou 730010, China
Dongqing Li: Key Laboratory of Cultivated Land Conservation Technology, Ministry of Agriculture and Rural Affairs, Gansu Yasheng Agricultural Research Institute, Co., Ltd., Lanzhou 730010, China
Xiaojun Yu: College of Grassland Science, Gansu Agricultural University, Lanzhou 730070, China

Agriculture, 2025, vol. 15, issue 3, 1-19

Abstract: In artificial grassland systems, the extensive use of inorganic nitrogen (N) fertilizers has greatly enhanced grassland yields but also caused significant environmental issues. The combined use of biochar and N fertilizer is recognized as an effective and sustainable approach to reducing environmental risks while boosting crop production. However, the specific impacts of biochar and N on alfalfa yield, soil properties, and root morphology remain unclear. This study examined the effects of three biochar application rates (0, 10, 20 t hm −2 ) and four N application levels (0, 47, 94, 188 kg N hm −2 yr −1 ) on alfalfa growth and soil characteristics. Results revealed that biochar notably promoted root development and increased osmoregulatory substance content. It enhanced root biomass by improving root nodule count, root neck bud formation, and root neck diameter, while N application reduced root nodule numbers. Biochar and N application reduced soil bulk density by 0.8–10.5%, with biochar further increasing available phosphorus and potassium levels. Additionally, their combined use significantly elevated soil nitrate and ammonium concentrations. Overall, the synergy of biochar and nitrogen application enhances alfalfa yield by fostering better root growth and improving soil fertility.

Keywords: N use efficiency; alfalfa biomass; root morphology; soil characteristics; correlation (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2025
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