Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland.
Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland.
Sci Total Environ. 2021 Feb 10;755(Pt 2):143551. doi: 10.1016/j.scitotenv.2020.143551. Epub 2020 Nov 6.
Soils store significant amounts of carbon (C) and thus can play a critical role for mitigating climate change. Crop roots represent the main C source in agricultural soils and are particularly important for long-term C storage in agroecosystems. To evaluate the potential of different farming systems to contribute to soil C sequestration and thus climate change mitigation, it is of great importance to gain a better understanding of the factors influencing root C allocation and distribution. So far, it is still unclear how root C allocation varies among farming systems and whether the choice of management practices can help to enhance root C inputs. In this study, we compared root C allocation in three main arable farming systems, namely organic, no-till, and conventional farming. We assessed root biomass, vertical root distribution to 0.75 m soil depth, and root-shoot ratios in 24 winter wheat fields. We further evaluated the relative importance of the farming system compared to site conditions and quantified the contribution of individual management practices and pedoclimatic drivers. Farming system explained one third of the variation in topsoil root biomass and root-shoot ratios, both being strongly positively related to weed biomass and soil organic C content and negatively to mineral nitrogen fertilization intensity. Root C allocation was significantly higher in organic farming as illustrated by an increase in root biomass (+40%) and root-shoot ratios (+60%) compared to conventional farming. By contrast, the overall impact of no-till was low. The importance of pedoclimatic conditions increased substantially with soil depth and deep root biomass was largely controlled by precipitation and soil texture, while the impact of management was close to zero. Our findings highlight the potential of organic farming in promoting root C inputs to topsoils and thereby contributing to soil organic matter build-up and improved soil quality in agroecosystems.
土壤储存着大量的碳(C)，因此在减缓气候变化方面可以发挥关键作用。作物根系是农业土壤中 C 的主要来源，对于农业生态系统中 C 的长期储存尤为重要。为了评估不同农业系统对土壤 C 固存和减缓气候变化的潜在贡献，深入了解影响根系 C 分配和分布的因素至关重要。到目前为止，人们仍不清楚不同农业系统之间根系 C 分配的差异，以及管理措施的选择是否有助于增强根系 C 的输入。在本研究中，我们比较了有机、免耕和常规三种主要旱地农业系统中的根系 C 分配。我们评估了 24 个冬小麦田的根系生物量、0.75 m 土壤深度的垂直根系分布和根冠比。我们进一步评估了农业系统相对于田间条件的相对重要性，并量化了个别管理措施和土壤气候驱动因素的贡献。农业系统解释了表土根系生物量和根冠比变异的三分之一，这两个变量都与杂草生物量和土壤有机碳含量呈正相关，与矿质氮施肥强度呈负相关。与常规农业相比，有机农业根系生物量（增加 40%）和根冠比（增加 60%）显著增加，表明有机农业根系 C 分配明显更高。相比之下，免耕的整体影响较低。土壤深度对土壤条件的重要性显著增加，深层根系生物量主要受降水和土壤质地控制，而管理的影响接近于零。我们的研究结果突出了有机农业在促进表土根系 C 输入方面的潜力，从而有助于农业生态系统中土壤有机质的积累和土壤质量的改善。
