Comparison of land nitrogen budgets for European agriculture by various modeling approaches

A comparison of nitrogen (N) budgets for the year 2000 of agro-ecosystems is made for the EU 27 countries by four models with different complexity and data requirements, i.e. INTEGRATOR, IDEAg, MITERRA and IMAGE. The models estimate a comparable total N input in European agriculture, i.e. 23.3–25.7 Mton N yr⁻¹, but N uptake varies more, i.e. from 11.3 to 15.4 Mton N yr⁻¹ leading to total N surpluses varying from 10.4 to 13.2 Mton N yr⁻¹. The estimated overall variation at EU 27 is small for the emissions of ammonia (2.8–3.1 Mton N yr⁻¹) and nitrous oxide (0.33–0.43 Mton N yr⁻¹), but large for the sum of N leaching and runoff (2.7–6.3 Mton N yr⁻¹). Unlike the overall EU estimates, the difference in N output fluxes between models is large at regional scale. This is mainly determined by N inputs, differences being highest in areas with high livestock density.     

The promising spread of sustainable agriculture in Asia

Despite great successes in increasing food production, Asia still faces enormous food security challenges. Most commentators agree that there will have to be increases in food production from existing agricultural land, but many are pessimistic about the future, judging likelihood of success on the basis of past performance of 'modern' agricultural development. Sustainable agriculture, though, offers entirely new opportunities, by emphasising the productive values of natural, social and human capital, all assets that Asian countries either have in abundance or that can be regenerated at relatively low financial cost.
This paper sets out an assets-based model of agricultural systems, together with a typology of eight approaches for sustainable agriculture improvements. In the 16 projects/initiatives spread across eight countries that are analysed, some 2.86 million households have substantially improved total food production on 4.93 million hectares, resulting in greatly improved household food security. Proportional yield increases are greatest in rainfed systems, but irrigated systems have seen small cereal yield increases combined with added production from additional productive system components (such as fish in rice, vegetables on dykes). The additional positive impacts on natural, social and human capital are also helping to build the assets base so as to sustain these improvements in the future.
This analysis indicates that sustainable agriculture can deliver large increases in food production in Asia. But spreading these to much larger numbers of farm households will not be easy. It will require fundamental policy reform.