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上的利益攸关方一再表示，他们渴望在不牺牲竞争力(价格或质量)的情况下将对环境的影响降至最低。为玉米生产制定更合理的氮肥管理策略将使加拿大农民能够同时实现这两个目标。氮肥损失对全球氮素生物地球化学循环和区域养分污染有着深远的影响，但对农民来说也是一种严重的经济低效。我们建议在“迟施”氮肥的基础上改进氮肥策略，在本季度比传统的氮肥施用量晚得多。大多数农民在种植期间施用氮肥，但迟施氮肥策略在季节较晚的时候，大约在种植后2.5个月，施用大部分氮肥。这一策略的好处是在玉米吸氮率高的时候同步施氮，从而降低了氮素高损失的风险。此外，由于氮肥是在季节中期施用的，晚施氮策略还允许农民改进他们的施氮量。在种植后等待2.5个月，农民可以评估天气、土壤和其他变量，以帮助他们更好地确定他们应该施用的氮肥用量。在种植周围施氮的农民就没有这种奢侈。随着农民对这一战略越来越感兴趣，加拿大和其他地方已经进行了验证后期氮素管理的概念验证研究。有必要制定最佳管理做法，使农民最大限度地受益于迟施氮肥战略，并减少氮肥使用的有害影响。该伙伴关系将为迟施氮肥建立最佳管理实践，量化谷物产量、经济收益、氮素挥发损失和其他与氮素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.