Agriculture Reference
In-Depth Information
typically values in the range from 45-60% would be possible under best crop
management practices (Cassman et al. 2002).
The necessary increases in staple food supplies in the next 20 years in Asia,
equaling those achieved in the recent past, will have to be realized mainly on highly
productive land where yields are high and labour becomes increasingly scarce.
There is, however, the complication of stagnating cereal yields in those areas where
long-term mono-cropping has been practiced - such as the Indo-Gangetic plains
with its rice-wheat systems or the humid tropics of South-east Asia with multiple
(double or triple) rice systems (Aggarwal et al. 2001; Dobermann et al. 2000;
Cassman and Harwood 1995).
As shown by recent research results from several DLO-IC projects in Asia (such
as VEGSYS, MAMAS, RMO Beijing and IRMLA; see De Jager et al. 2007),
diversification of agricultural production - away from rice and towards vegetable
and livestock production - creates substantial additional environmental pressures
that require a whole set of new management practices and policy interventions to
avoid serious damage to the environment (Wolf et al. 2003; Hengsdijk et al. 2007;
Van den Berg et al. 2007).
Another serious constraint to food production in Asia is water scarcity. In the North
China plain, known as the granary of China, water tables have been dropping con-
tinuously over the last two decades as a consequence of excessive extraction (Figure 8).
In short, current resource management practices cannot cope with the challenges
facing East and South-east Asia. Past productivity growth was based on the
increasing use of resources, but future developments should be aimed at more
efficient use of resources.
Groundwater table (m)
0
-5
-10
-15
-20
-25
-30
-35
-40
1980
1986
1992
1998
Ye a r
Figure 8.
Dynamics of groundwater table depth (m) over the past 25 years in Hebei province,
China (based on Jianxia et al. 2005)
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