Keynote Lectures

Description

Forages have a high N demand, a long growing season, and an effective root system all contributing to effective nutrient capture. However forages are restrictive in methods available for mitigating gaseous losses both as NH3 and as N2O, due to both practical and cost considerations. Strategies are needed to address the challenges of both N efficiency and N losses. Agronomic techniques in long term experiments can enhance estimates of N loss pathways and N efficiency, and demonstrate the importance of integrated multinutrient approaches. The dual manure stream concept divides manure into a thin fraction suitable as an N source for grass and a sludge fraction suitable as a P source for corn. While this represents an integrated approach, questions remain about alternate loss pathways. While grazing greatly reduces ammonia emissions it is not clear that grazing improves N use relative to confinement systems. The current levels of prospective mitigation of emissions are perhaps modest. However new approaches such as acidifying manure, novel nitrification inhibitor products, more durable legume stands, ongoing improvements in manure application methodology with increasing adoption by farmers, and novel integrated approaches will continue to make incremental improvements in reducing losses of nitrogenous gases and other reactive N species and improving nutrient efficiency of forages.

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Nitrogen Management of Forages in Relation to Gaseous Emissions – New Approaches and Considerations

Forages have a high N demand, a long growing season, and an effective root system all contributing to effective nutrient capture. However forages are restrictive in methods available for mitigating gaseous losses both as NH3 and as N2O, due to both practical and cost considerations. Strategies are needed to address the challenges of both N efficiency and N losses. Agronomic techniques in long term experiments can enhance estimates of N loss pathways and N efficiency, and demonstrate the importance of integrated multinutrient approaches. The dual manure stream concept divides manure into a thin fraction suitable as an N source for grass and a sludge fraction suitable as a P source for corn. While this represents an integrated approach, questions remain about alternate loss pathways. While grazing greatly reduces ammonia emissions it is not clear that grazing improves N use relative to confinement systems. The current levels of prospective mitigation of emissions are perhaps modest. However new approaches such as acidifying manure, novel nitrification inhibitor products, more durable legume stands, ongoing improvements in manure application methodology with increasing adoption by farmers, and novel integrated approaches will continue to make incremental improvements in reducing losses of nitrogenous gases and other reactive N species and improving nutrient efficiency of forages.