Agricultural Water Management (Apr 2024)

Straw-derived biochar optimizes water consumption, shoot and root characteristics to improve water productivity of maize under reduced nitrogen

  • Ru Guo,
  • Rui Qian,
  • Luning Du,
  • Weili Sun,
  • Jinjin Wang,
  • Tie Cai,
  • Peng Zhang,
  • Zhikuan Jia,
  • Xiaolong Ren,
  • Xiaoli Chen

Journal volume & issue
Vol. 294
p. 108722

Abstract

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Optimizing water and nitrogen (N) utilization to enhance crop yields under resource constraints is crucial. Straw and its biochar, combined with N fertilizer, are commonly used to improve soil carbon storage and crop growth. However, the effects of straw and N fertilizer management on water consumption, root and shoot characteristics, N uptake, and maize productivity remain unclear. To address this knowledge gap, a three-year (2019–2021) field experiment was conducted in Northwest China. We compared two straw incorporation methods [straw (SI) and straw-derived biochar (BI)] with straw removal (NI) at four N application rates [0 (N0), 225 (N225), 300 (N300), and 375 kg ha–1 (N375)]. Results indicated that compared with NI, both SI and BI significantly increased grain yield (GY), N uptake, and water productivity (WP) (SI < BI; P < 0.05). The maximum GYs were achieved with SIN300 and BIN225, respectively. Notably, compared with SIN300, BIN225 significantly enhanced GY by 10.8% and 5.8% and improved WP by 19.2% and 9.9% (P < 0.05). This improvement was mainly attributed to the increased water consumption after tasseling and crop transpiration (T) in evapotranspiration (ET). Furthermore, N application resulted in increased root distribution in shallow soil layers (0–0.3 m). Under BIN225, roots exhibited a longer, thinner and deeper profile, minimizing root redundancy and enhancing root efficiency in water and N absorption during the reproductive stage of maize. In contrast, SIN300 resulted in shorter, thicker, and shallower roots, leading to a reduced shoot-root ratio of 12.2% (P < 0.05). Based on the normalization and fitting curves, BI combined with reduced N (240 kg ha–1) improved WP by 24.5%, achieving 98.7% of the maximum GY for drip-irrigated maize (16.98 Mg kg–1). Overall, these findings provide a novel straw strategy for sustainable field management in arid irrigation agriculture and similar ecosystems.

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