Wood chip biochar coupled with moderate water stress enhances peanut nutrient uptake, yield, and water use efficiency

Biochar application can improve soil conditions, enhance nutrient uptake, and increase crop productivity, particularly under water stress. However, the comparative effects of biochar derived from different feedstocks on peanut growth and yield remain unclear. A two-year pot experiment was conducted to examine the impacts of maize straw biochar (B M ) and wood chip biochar (B W ) on peanut growth, nutrient uptake, water use efficiency (WUE), and soil nitrogen (N) and potassium (K) availability under three irrigation regimes: well-watered (I WW ), moderate water stress (I MS ), and severe water stress (I SS ). Water stress (I MS and I SS ) increased soil NH 4 + -N, NO 3 – -N, and available K relative to I WW , likely due to reduced plant nutrient uptake. Nevertheless, total N and K uptake by plants declined under stress, leading to 15.7–47.5% yield reductions. Biochar application mitigated these effects, improving plant height by 5.3–18.2%, leaf area by 4.1–13.4%, N uptake by 2.8–20.0%, K uptake by 11.6–21.6%, yield by 10.1–54.6%, and WUE by 1.4–46.0%, compared with the control. Notably, B W outperformed B M in promoting nutrient uptake and yield, particularly under stress, due to its higher intrinsic N and K, and superior cation exchange capacity. The I MS B W combination produced the highest N and K uptake and yield, achieving yields comparable to well-watered controls (I WW B 0 ) but with reduced water use, resulting in significantly higher WUE. These results suggest that wood chip biochar application under moderate water stress offers a sustainable strategy to enhance peanut productivity in arid regions.