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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=652828
• 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.

氮素预算在有机种植系统中是一项复杂的任务，因为作物施肥是以有机肥(动物粪便、覆盖作物、堆肥等)为基础的。而不是现成的矿物质肥料。关于这些有机肥对后茬作物营养的贡献，特别是覆盖作物根部对土壤氮素收支的贡献，仍有许多未知之处。事实上，在估计覆盖作物对氮素收支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，覆盖作物的根系被认为对农业土壤的土壤氮素供应有相当大的贡献。以前还没有研究解决这些重要的和创新的研究问题。*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。该研究计划的短期目标是：1)量化和区分覆盖作物地上部和根部对土壤氮素动态的贡献；2)改进现有的覆盖作物残留物N向土壤有机和无机形态转移的概念模型；3)阐明覆盖作物根部分解产生的N在土壤-植物连续体中的时间动态；4)使覆盖作物分解的N供应与有机管理下种植的经济作物的N吸收同步。*将进行2个田间试验和1个培养研究，以实现研究目标。大田试验1将比较不同覆盖作物品种在不同终止阶段的地上部和根部特征，以及它们对有机玉米营养的贡献。长期培养研究将量化覆盖作物的根和地上部对土壤氮素供应的贡献。第二个田间试验将使用在富含15N的环境中生长的覆盖作物材料进行，以解决关于N在不同土壤N组分中分配的具体未知问题。*我的研究将提供对覆盖作物根系分解和相关土壤N向植物以及土壤储备和植物补给的基本理解。这将允许更好地估计土壤对后续作物的氮素供应，从而更好地预测对其他有机氮素改良剂的需求。关于覆盖作物根系实际贡献的知识将被整合到农场N预算中，因此从概念上促进了有机种植系统中的覆盖种植和养分预算。此外，由于更好的氮素管理和时机，作物产量的增加将为农民带来重要的收入增长。在更广泛的范围内，收集有关土壤氮素收支的信息可能有助于减少有机耕作等以覆盖作物为基础的种植制度造成的氮素损失。