| Autor: |
Jensen, L S, Schjoerring, J K, van der Hoek, K W, Poulsen, Hanne Damgaard, Zevenbergen, J F, Pallière, C, Brentrup, F, Jongbloed, Aa W, Willems, J, van Grinsven, H |
| Jazyk: |
angličtina |
| Rok vydání: |
2011 |
| Zdroj: |
Jensen, L S, Schjoerring, J K, van der Hoek, K W, Poulsen, H D, Zevenbergen, J F, Pallière, C, Brentrup, F, Jongbloed, A W, Willems, J & van Grinsven, H 2011, Benefits of nitrogen for food, fibre and industrial production . in The European Nitrogen Assessment : Sources, Effects and Policy Perspectives . Cambridge University Press, pp. 32-61 . |
| Popis: |
Nature of the issue • Reactive nitrogen (N r ) has well-documented positive effects in agricultural and industrial production systems, human nutrition and food security. Limited N r supply was a key constraint to European food and industrial production, which has been overcome by N r from the Haber–Bosch process. • Given the huge diversity in N r uses, it becomes a major challenge to summarize an overall inventory of N r benefits. This full list of benefi ts needs to be quantified if society is to develop sound approaches to optimize N r management, balancing the benefi ts against the environmental threats. Approaches • When reviewing trends in European N r production rates, including those from chemical and biological fi xation processes, and the consumption of this N r in human activities, agriculture is by far the largest sector driving N r creation. • Particular attention has been given to relationships between N application rates, productivity and quality of products from major crops and livestock types, including consideration of the mechanisms underlying variations in N response/outputs and the derived impacts on land use and land requirements. Key findings/state of knowledge • The economic value of N benefi ts to the European economy is very substantial. Almost half of the global food can be produced because of N r from the Haber–Bosch, and cereal yields in Europe without fertilizer would only amount to half to two-thirds of those with fertilizer application at economically optimal rates. • There is a wide variety in N responses at field level. For cereals, nitrogen productivity, also termed the agronomic efficiency, averages 41 kg grain per kg applied fertilizer N across the EU countries, with significant variation between the member states. Variation reflects differences in crop type, farm type, cropping practices, area, region, soil fertility and climate. • Farmers have an economic incentive to apply only the economically optimal rate of fertilizer N, but there is no strong incentive to increase N use effi ciency as the economic return on using fertilizer N is very robust, especially in high value crops. However, recent initiatives to reduce environmental impacts of N r losses have led to an increase of N use effi ciency in both crop and livestock production. • Increasing fertilizer prices and climate change will create new incentives to increase N use effi ciency. Th ere are ample options to achieve this via N-conserving field practices such as catch crops, reduced soil tillage, better estimation of crop N requirements and improved timing and placement of N inputs. Also modifications to livestock diets, enhanced recycling of livestock wastes, prevention of ammonia loss from animal housing and fi eld manure application can enhance benefits per unit applied N r . Plant materials with improved composition of major storage compounds and novel feed additives, e.g. proteins from bio-fuel production, can also improve feed N responses per unit mass N r used. Recommendations • Legislative drivers to reduce N r use, including mineral fertilizer, must take account of the nitrogen benefi ts in agricultural production needed to maintain food and energy security, given the limited options to increase arable land area. • New technological tools should be implemented to improve nitrogen-effi ciency and the overall benefi ts of N r use. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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