A groundbreaking study published in the journal Biochar emphasizes the critical importance of feedstock selection on the long-term agronomic benefits of biochar application in maize cultivation, particularly under water-limited conditions. This research, spearheaded by scientists from Northwest A&F University in China and the University of Copenhagen, reveals that the residual effects of biochar heavily depend on whether it is derived from wheat-straw or softwood. The findings resoundingly indicate that wheat-straw biochar, when integrated with an alternate partial root-zone drying (APRD) irrigation system, substantially boosts maize productivity and resource use efficiency for multiple growing seasons after just a single application.
Biochar, a porous, carbon-rich material created through pyrolysis of biomass, has generated growing interest due to its potential to enhance soil properties, improve nutrient cycling, and sequester carbon. While many studies have evaluated its immediate impact on crop growth, this investigation delves deeper, focusing on the sustained influences of two distinct biochar types on maize nitrogen uptake, biomass accumulation, and both water and nitrogen use efficiencies. The researchers employed rigorous greenhouse experiments over two consecutive years to assess how varying biochar feedstocks interact with irrigation modalities to influence soil microbial dynamics and crop performance.
The experimental setup involved applying softwood and wheat-straw biochars into soils supporting maize growth under three irrigation regimes: full irrigation, deficit irrigation, and the more nuanced alternate partial root-zone drying. APRD is an increasingly recognized water management strategy in which only one side of the root system receives water at a time, prompting plants to develop resilience to drought stress through alternating root zone wetting. This method stimulates physiological responses that improve water and nutrient uptake efficiencies while conserving scarce water resources, making it a promising technique for arid and semi-arid agricultural regions.
Crucially, the results starkly contrasted the outcomes associated with the two biochar types. Wheat-straw biochar consistently enhanced maize total biomass by up to 30%, elevated water use efficiency by 27%, and improved nitrogen use efficiency by roughly 10% compared to treatments without biochar under APRD. These notable improvements are attributed to wheat-straw biochar’s positive modulation of soil microbial activity and increased nitrogen availability. Enhanced microbial respiration under this treatment stimulated root proliferation and nutrient absorption, thereby bolstering crop resilience against water deficit stress.
Conversely, softwood biochar exhibited an initial deleterious effect on soil microbial respiration and nitrogen dynamics, leading to reduced root development and suppressed maize yields in the first growing season. This phenomenon is likely due to the more recalcitrant nature of softwood biochar’s stable carbon structure, which temporarily limits nutrient mineralization and microbial accessibility. However, the study observed a gradual attenuation of these negative impacts in the subsequent season as the soil microbial community adapted, indicating a delayed but eventual stabilization of soil biological functions in the presence of woody biochar.
The synergy between irrigation strategy and biochar type was also a focal point of the investigation. APRD irrigation alone significantly influenced nitrogen mineralization and enhanced water conservation, but its benefits were maximized when combined with wheat-straw biochar amendment. The alternating cycles of drying and rewetting inherent to APRD appear to activate soil microbial processes that facilitate nutrient release, while fostering deeper and more efficient root systems capable of sustaining crop productivity during intermittent water scarcity.
Lead author Heng Wan highlights the transformative potential of integrating crop-residue-derived biochar with precision irrigation techniques for sustainable agriculture. This integrative approach not only maintains soil fertility and promotes steady crop outputs under water-limited conditions but also reduces dependence on external inputs such as synthetic fertilizers and excessive water use. These multi-seasonal benefits align with broader goals of enhancing agroecosystem resilience in the face of climate change-induced drought risks.
At a mechanistic level, the contrasting effects of biochar types elucidate the complex interactions between biochar physicochemical properties, soil microbial ecology, and plant root dynamics. Wheat-straw biochar’s more labile carbon fractions likely serve as substrates for soil microbes, fostering a vibrant microbial community that facilitates nutrient cycling. Meanwhile, softwood biochar’s carbon matrix presents a more structurally recalcitrant environment, initially hindering microbial activity but eventually contributing to soil organic matter stabilization.
This pioneering research underscores the necessity for targeted biochar selection based on feedstock origin to optimize agronomic outcomes across diverse irrigation regimes. The ability of wheat-straw biochar to sustain maize growth under APRD irrigation emphasizes its suitability for water-scarce environments, where maximizing crop productivity with minimal resource inputs is paramount. Furthermore, understanding the temporal shifts in biochar effects provides critical insights into managing soil amendments for long-term agroecological benefits.
The implications extend beyond immediate crop yields, touching on broader sustainability challenges. By enhancing nitrogen use efficiency, straw-derived biochar reduces the risk of nitrogen leaching and associated environmental pollution, while improving water use efficiency mitigates stress on increasingly constrained freshwater resources. Such integrated soil-water-nutrient management strategies are vital for advancing dryland agriculture and ensuring food security in arid regions globally.
In summary, this comprehensive study charts a promising path forward for sustainable intensification of agriculture by marrying biochar technology with precision irrigation. These innovations hold the promise of transforming marginal lands into productive agroecosystems that are both environmentally sound and economically viable. As water scarcity and soil degradation continue to threaten global food systems, the findings provide a robust scientific foundation for deploying crop-residue biochar in concert with advanced irrigation techniques to secure future agricultural productivity.
The research is a clarion call for policymakers and farmers to rethink conventional soil amendment and irrigation practices, promoting a more nuanced, resource-efficient paradigm that harmonizes plant physiology, microbial ecology, and water management. Through such interdisciplinary approaches, the quest for resilient, high-yielding, and sustainable cropping systems becomes attainable.
Subject of Research: Not applicable
Article Title: Contrasting residual effects of different biochar types on maize nitrogen uptake, biomass accumulation, water and nitrogen use efficiency under alternate partial root-zone drying irrigation
News Publication Date: 20-Oct-2025
Web References:
References:
Wan, H., Hong, M., Fang, L. et al. Contrasting residual effects of different biochar types on maize nitrogen uptake, biomass accumulation, water and nitrogen use efficiency under alternate partial root-zone drying irrigation. Biochar 7, 115 (2025).
Image Credits: Heng Wan, Mei Hong, Liang Fang, Yazen Al-Salman, Loes van Schaik, Zhenhua Wei, Fei Li, Violette Geissen & Fulai Liu
Keywords: Agriculture, Agronomy, Microbiology, Soil science, Environmental sciences
