Chapter in book: Agriculture and climate beyond 2015. A new perspective on future land use patterns.
Changes in agricultural production systems
In this book chapter we describe the observed changes in agricultural production systems in recent decades, and assess the changes that may occur in the coming decades. The focus is on consequences of changing livestock production systems for the use of grassland and arable land, feed resource use, N fertilizer inputs and animal manure management, and consequences of changing production systems for emissions of greenhouse gases.
Increase of N in animal manure
The results indicate that the global production of N in animal manure has increased strongly in the 1970-1995 period from 83 to 104 Tg yr-1 and will continue to grow to 127 Tg yr-1 in the coming three decades. Most of this increase is the result of expanding livestock production in the developing countries, while in other countries the animal manure N production stabilizes (industrialized countries) or will show a slight increase (transition countries). The use of N fertilizers will also strongly increase in the developing countries (from 53 to 73 Tg yr-1) and less so in the industrialized countries (26 to 31 Tg yr-1).
Methane emission from ruminant production
An important environmental consequence of ruminant production is the emission of methane, one of the major greenhouse gases. Our projection suggests that the global annual methane emission will strongly increase from 85 Tg now to 120 Tg in 2030, mainly as a result of a fast growth in developing countries. Enteric fermentation will thus have a growing contribution to the global CH4 emission. Similar developements are expected for N2O and NH3. Global direct emissions of N2O from animal manure strongly increased from 1.2 to 1.4 Tg N2O-N yr-1 between 1970 and 1995. For the coming three decades a further increase to 1.7 Tg is projected. Similar increases for emissions of NH3 are foreseen. The N2O emissions from N fertilizer use increased from 0.4 Tg N2O-N yr-1 in 1970 to 1 Tg in 1995 and will rapidly increase in the coming three decades to 1.4 Tg N2O-N yr-1.
Furthermore, increasing production and further intensification in mixed/industrial livestock production systems means a concentration of activities, particularly of manure availability, which may lead to local losses to the environment (emissions to air and groundwater). In addition, there is concern about animal well-being, particularly in landless systems, which will gain importance in all world regions in the projection used.
Characteristics of livestock production
Regarding livestock production, it is clear that while the extensively used pastoral grassland and the area of intensively used grassland in mixed/industrial systems show gradual changes, the production characteristics change with trends towards intensification and integration of a growing part of livestock production in mixed crop and livestock production systems.
Turning to land-use aspects of livestock production, we see that the dependence of ruminant production on grassland resources is declining, and the importance of food crops and other feedstuffs is increasing. Despite this decreasing importance of grass as a feed resource, a fast grass production increase of 33% is needed. This increase will have to come from improved management. In addition, vast increases in arable land are required to produce the food crops needed for both ruminant and pork and poultry production.