Can Cover Crops Reduce Nitrous Oxide Emissions from Agricultural Soils?

覆盖作物可以减少农业土壤中的一氧化二氮排放吗？

基本信息

批准号：
RGPIN-2018-06454
负责人：
Tenuta, Mario
金额：
$ 3.72万
依托单位：
University of Manitoba
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=712986
关键词：
Cover Crops Reduce Nitrous Oxide

项目摘要

Despite recent emission reductions of greenhouse gases (GHG) by most economic sectors in Canada, agriculture is lagging. This is because doubling in synthetic N fertilizer use in the past several decades for crop production has increased emissions of the greenhouse gas, nitrous oxide (N2O). Lowering emissions from Canadian agricultural soils is imperative if as a nation, we are to meet international commitments to greenhouse gas reductions. Further, crop production must modernize to limit nitrogen loss to the environment and increase fertilizer N utilization by crops. Ultimately, we must strive to create new agricultural systems that don't emit greenhouse gases and conserve nutrients in crops. Organic food production systems are thought to decrease net GHG emissions compared to conventional systems. However, the common practice of incorporating legume forages as green manures results in carry over of nitrate nitrogen over winter and very large emissions of N2O during the following thaw, if the soil is saturated. Thaw emissions also occur in conventional crop production accounting for 15-50% of annual N2O emissions from agricultural soils in the cold winter climates of Canada. Farmers are adopting cover cropping where plants sown following harvest of annual grains or oilseeds provide soil cover from fall through spring. There are multiple benefits to cover cropping including lowering soil nitrate levels going into winter. What the impact of this lowering of nitrate levels has on thaw emissions of N2O is not known for our climate. Past studies in warmer climates indicate that cover crops can increase emissions by feeding soil organisms producing N2O. Thus, it is important to know if the increasingly popular practice of cover cropping is decreasing or increasing N2O emissions. As part of the journey of my laboratory toward its long-term goal of changing how food is produced to be a net non-emitter of GHGs from soil, this Discovery Grant program focuses on answering the following questions; a) do covers reduce or increase thaw N2O emissions following alfalfa ploughdown in organic production?, b) do covers reduce or increase thaw emissions in conventional production?, c) can covers lower nitrate and soil moisture to limit thaw emissions?, d) what is the net result of feeding soil organisms and lowering nitrate with covers on N2O emissions; does moisture affect the balance?, e) how do microbial genes producing N2O relate to thaw emissions and effects of covers, management, and soil conditions?, and f) can the widely used simulation model, DNDC, predict cover effects on emissions?. The outcome of this program is to foster practices to decrease N2O emissions from crop production. The implications are to help in reversing the recent trend for increasing N2O emissions from agricultural soils and meet commitments to actually reduce them.

尽管加拿大大多数经济部门最近都减少了温室气体（GHG）排放，但农业仍然滞后。这是因为过去几十年来，农作物生产中合成氮肥的使用量增加了一倍，增加了温室气体一氧化二氮 (N2O) 的排放量。如果作为一个国家，我们要履行减少温室气体排放的国际承诺，那么降低加拿大农业土壤的排放势在必行。此外，作物生产必须实现现代化，以限制氮素向环境的流失，并提高作物对肥料氮的利用率。最终，我们必须努力创建不排放温室气体并保存作物养分的新农业系统。与传统系统相比，有机食品生产系统被认为可以减少温室气体净排放量。然而，如果土壤饱和，将豆科牧草作为绿肥的常见做法会导致硝酸氮在冬季滞留，并在随后的解冻过程中排放大量氧化亚氮。在加拿大寒冷的冬季气候下，传统作物生产中也会产生解冻排放，占农业土壤年氧化亚氮排放量的 15-50%。农民正在采用覆盖种植，即在收获一年生谷物或油籽后播种植物，以提供从秋季到春季的土壤覆盖。覆盖作物有多种好处，包括降低冬季土壤硝酸盐水平。硝酸盐水平的降低对 N2O 解冻排放量的影响尚不清楚。过去在温暖气候下的研究表明，覆盖作物可以通过喂养产生氧化亚氮的土壤生物来增加排放量。因此，了解日益流行的覆盖种植做法是否会减少或增加 N2O 排放量非常重要。作为我的实验室实现改变食品生产方式，使其成为土壤温室气体净非排放者的长期目标的一部分，该发现资助计划重点回答以下问题： a) 覆盖物是否会减少或增加有机生产中紫花苜蓿耕作后的解冻 N2O 排放？, b) 覆盖物是否会减少或增加常规生产中的解冻排放？, c) 是否可以覆盖较低的硝酸盐和土壤湿度以限制解冻排放？, d) 什么是喂养土壤生物和降低硝酸盐并覆盖 N2O 排放的最终结果；水分会影响平衡吗？e) 产生 N2O 的微生物基因与解冻排放以及覆盖物、管理和土壤条件的影响有何关系？以及 f) 广泛使用的模拟模型 DNDC 能否预测覆盖物对排放的影响？该计划的成果是促进减少农作物生产中氧化亚氮排放的实践。其影响将有助于扭转近期农业土壤氧化亚氮排放量增加的趋势，并履行实际减少排放量的承诺。