To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Farms represent operational units which determine N-use efficiency and incorporation into products and, collectively, at the wider scale, determine the extent of environmental losses from agriculture.
The basic principles and objectives of using N, from whatever source, pertain to different systems across the wide range of farming types across Europe.
In addition to managing external inputs (fertilisers), there is much opportunity to improve N transfers within the farm. Mineral fertilisers are added to balance supply/demand for crops. Some systems rely on legume-N which, once incorporated into farm cycles, behaves in the same way as other N forms.
Farm N cycles, their constituent parts and controlling influences are described and generalised principles identified.
Farm budgets for a range of systems, focussing on typical practice in NW Europe are shown which illustrate some general, important differences between farming systems.
Key findings/state of knowledge
Benefits of using N effectively are far reaching with immediate impact in promoting production. Use of N also provides an effective and flexible management tool for farmers.
Crop N requirements are determined from response curves and economic optima. Advice is supplied to farmers from various sources but the extent to which it is taken depends on many factors. New technologies are available to improve N-use efficiency. The basis of good N management is to optimise efficiency of added and soil N by increasing the temporal and spatial coincidence between availability and uptake of N.
Reactive nitrogen (Nr) has well-documented positive effects in agricultural and industrial production systems, human nutrition and food security. Limited Nr supply was a key constraint to European food and industrial production, which has been overcome by Nr from the Haber–Bosch process.
Given the huge diversity in Nr uses, it becomes a major challenge to summarize an overall inventory of Nr benefits. This full list of benefits needs to be quantified if society is to develop sound approaches to optimize Nr management, balancing the benefits against the environmental threats.
When reviewing trends in European Nr production rates, including those from chemical and biological fixation processes, and the consumption of this Nr in human activities, agriculture is by far the largest sector driving Nr 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 benefits to the European economy is very substantial. Almost half of the global food can be produced because of Nr 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.
Email your librarian or administrator to recommend adding this to your organisation's collection.