Elucidating the role and contribution of cover crop roots to soil fertility and crop nutrition in organic cropping systems

阐明有机耕作系统中覆盖作物根系对土壤肥力和作物营养的作用和贡献

• 批准号: RGPIN-2016-05273
• 负责人: Halde, Caroline
• 金额: $ 1.68万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=709632
• 关键词: Elucidating; role; contribution; cover; crop

Nitrogen budgeting is a complex task in organic cropping systems, because crop fertilization is based on organic fertilizers (animal manures, cover crops, compost, etc.) rather than readily available mineral fertilizers. Many unknowns remain on the contribution of these organic fertilizers to the nutrition of subsequent crops, and particularly on the contribution of cover crop roots to soil N budget. Indeed, generally, only the shoot biomass of cover crops is considered when estimating the contribution of cover crops to nitrogen budget and fertilization plan. However, cover crop roots are hypothesized to contribute considerably to the soil N supply of agricultural soils. No research has previously addressed these important and innovative research questions. The long-term objective of the proposed research program is to elucidate the mechanisms of contribution of cover crop roots to soil fertility and crop nutrition. The short-term objectives of the proposed research program are 1) to quantify and differentiate the contribution of cover crop shoots and roots to the soil N dynamics; 2) to improve the current conceptual model of transfer of cover crop residue N into various soil organic and inorganic fractions; 3) to elucidate the temporal dynamics of N derived from the decomposition of cover crop roots in the soil-plant continuum; and 4) to synchronize the N supply from decomposing cover crops with N uptake of cash crops grown under organic management. Two field experiments and one incubation study will be conducted to achieve the research objectives. The field experiment #1 will compare the shoot and root characteristics of different cover crop species incorporated at different termination stages, and their contribution to organic corn nutrition. The long-term incubation study will quantify the contribution of cover crop roots and shoots to soil N supply. A second field experiment will be conducted using cover crop material grown in 15N-enriched environment, to address specific unknowns about N partitioning in various soil N fractions. My research will provide a fundamental understanding of cover crop root decomposition and associated soil N supply to plants and to the replenishment of the soil reserve and to plants. This will allow for better estimation of the soil N supply to subsequent crops and, therefore, for better forecasting of the need for other N organic amendments. Knowledge of the actual contribution of cover crop roots will be integrated in farm N budgets, therefore conceptually advancing the cover cropping and nutrient budgeting in organic cropping systems. Moreover, increase in crop yield due to better N management and timing would represent important gains in revenues to farmers. On a broader scale, gathering information on soil N budget may help to reduce N losses from cover crop-based cropping systems like organic farming systems.

在有机种植系统中，氮预算是一项复杂的任务，因为作物施肥是基于有机肥料（动物粪便、覆盖作物、堆肥等），而不是现成的矿物肥料。这些有机肥料对后续作物营养的贡献仍然存在许多未知数，特别是覆盖作物根部对土壤氮预算的贡献。事实上，在估计覆盖作物对氮预算和施肥计划的贡献时，通常只考虑覆盖作物的地上部生物量。然而，据推测覆盖作物根部对农业土壤的土壤氮供应有很大贡献。此前还没有研究解决这些重要且创新的研究问题。 拟议研究计划的长期目标是阐明覆盖作物根系对土壤肥力和作物营养的贡献机制。拟议研究计划的短期目标是 1）量化和区分覆盖作物芽和根对土壤氮动态的贡献； 2）改进目前将覆盖作物残留物氮转移到各种土壤有机和无机部分的概念模型； 3）阐明土壤-植物连续体中覆盖作物根系分解产生的氮的时间动态； 4) 使腐烂覆盖作物的氮供应与有机管理下经济作物的氮吸收同步。 为了实现研究目标，将进行两项现场实验和一项孵化研究。田间实验#1将比较在不同终止阶段纳入的不同覆盖作物品种的芽和根特征，以及它们对有机玉米营养的贡献。长期孵化研究将量化覆盖作物根和芽对土壤氮供应的贡献。第二项田间实验将使用在富含 15N 的环境中生长的覆盖作物材料进行，以解决有关各种土壤氮组分中氮分配的具体未知问题。 我的研究将为覆盖作物根部分解以及相关的土壤氮向植物的供应以及土壤储备和植物的补充提供基本的了解。这将有助于更好地估计后续作物的土壤氮供应，从而更好地预测其他氮有机改良剂的需求。有关覆盖作物根部实际贡献的知识将纳入农场氮预算，从而从概念上推进有机耕作系统中的覆盖作物和养分预算。此外，由于更好的氮管理和时机而导致的作物产量的增加将为农民带来重要的收入收益。在更广泛的范围内，收集有关土壤氮预算的信息可能有助于减少有机耕作系统等以覆盖作物为基础的耕作系统的氮损失。