Conclusions

A number of conclusions can be drawn from the analyses discussed in this chapter for the historical period 1970-1995 and the projection towards 2030 for global crop and livestock production systems. The primary findings relate to livestock production characteristics and feed resources, consequences for land use, the global N cycle and emissions of greenhouse gases.

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

Table 5.5 Regional and global fertilizer-induced N2O emissions from N fertilizers and animal manure expressed as emission of N2O-N in Tg/yr and % of total emission from all sources for 1970, 1995 and 2030

Year

Developing

Industrialized

Transition

World

countries

countries

countries

(Tg/yr) (%)

(Tg/yr)

(%)

(Tg/yr)

(%)

(Tg/yr)

(%)

N fertilizer

1970

0.1 2

0.2

8

0.1

12

0.4

3

1995

0.7 7

0.3

13

0.1

10

1 .0

7

2030

0.9 8

0.4

16

0.1

9

1 .4

8

Animal manure

1970

0.7 11

0.3

13

0.1

20

1 .2

9

1995

1 .0 11

0.3

13

0.1

22

1 .4

10

2030

1.3 11

0.3

13

0.1

16

1.7

10

Note: Calculations are based on IPCC (1997).

Note: Calculations are based on IPCC (1997).

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.

The global production of N in animal manure has increased strongly in the 1970-1995 period from 83 to 104 Tg/yr and will continue to grow to reach a level of 127 Tg/yr 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) and less so in the industrialized countries (26 to 31 Tg/yr).

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 developments 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 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 in 1970 to 1 Tg in 1995 and will rapidly increase in the coming three decades to 1.4 Tg N2O-N/yr.

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.

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