Developing best management practices for late nitrogen applications in corn

包括消费者在内的整个农业食品价值链的利益攸关方沿着一再表示，他们希望粮食生产做法能够在不牺牲竞争力（价格或质量）的情况下最大限度地减少对环境的影响。为玉米生产制定更合理的氮肥管理策略将使加拿大农民同时实现这两个目标。肥料氮损失对全球氮素地球化学循环和区域养分污染有着深远的影响，但它们也代表着农民的显著经济效率低下。我们建议完善氮肥策略的基础上'晚' N肥的应用，应用N肥在本赛季远晚于传统的做法。大多数农民在种植前后施用氮肥，但晚施氮肥策略在种植季节晚得多的时候（种植后约2.5个月）施用大部分氮肥。这种策略的好处是，当玉米氮素吸收率高时，同步施用肥料氮，这降低了高氮素损失的风险。此外，由于氮肥是在中期施用的，因此后期氮肥策略也允许农民调整氮肥施用量。种植后等待2.5个月可以让农民评估天气，土壤和其他变量，以帮助他们更好地确定他们应该应用的氮量。一个农民在种植周围施氮就没有这种奢侈了。在加拿大和其他地方，随着农民对这一战略越来越感兴趣，已经进行了验证后期氮肥管理的概念验证研究。有必要制定最佳的管理措施，最大限度地提高农民后期氮肥战略的效益，减少氮肥使用的有害影响。该伙伴关系将建立后期施氮的最佳管理实践，量化粮食产量、经济回报、氮挥发损失和其他与氮相关的作物和土壤变量。

Stakeholders along the entire agri-food value chain, including consumers, have repeatedly stated their desire for food production practices that minimize environmental impacts without sacrificing competitiveness (price or quality). Developing more rational nitrogen (N) fertilizer management strategies for corn production would allow Canadian farmers to meet both goals simultaneously. Fertilizer N losses have a profound impact on global N biogeochemical cycling and regional nutrient pollution, but they also represent a significant economic inefficiency for the farmer. We are proposing to refine an N fertilizer strategy based on 'late' N fertilizer applications, applying N fertilizer much later in the season than traditionally done. Most farmers apply N fertilizer around planting, but late N strategies apply a large proportion of this N much later in the season, about 2.5 months after planting. This strategy has the benefit of synchornizing the application of fertilizer N to when corn N uptake rates are high, which reduces the risk of high N losses. Moreover, because fertilizer N is applied mid-season, late N strategies also allow farmers to refine the N rate they apply. Waiting 2.5 months after planting allows farmers to assess weather, soil and other variables to help them better determine the N rate they should apply. A farmer applying N around planting does not have this luxury. Proof-of-concept studies validating late N management have been carried out in Canada and elsewhere as farmers are increasingly interested in the strategy. There is a need to develop best management practices that maximize the benefits of late N strategies for farmers and reduce the deleterious impacts of N fertilizer use. The partnership will establish best management practices for late N applications, quantifying grain yield, economic returns, N volatilization losses and other N-related crop and soil variables.