407In this model diagram, the flat land (first zone) at the foot of hill has the best
ecological conditions; it could only grow a variety of dryland cash crops after basic
food supply was guaranteed in the past. Rainwater-harvesting system provides a
certain amount of available water resource, which can be used for introducing the
cash crops with high additional value in flat lands, such as off-season greenhouse
vegetables, flowers, fruits and so on. However, these lands only consisted of a small
proportion of total lands, i.e. generally less than 5 % in hilly and gully region.
The second zone comprises most of the remaining flat fields and the lower ter-
race lands. This lands have the advantages as fine soil quality, excellent production
conditions, and high suitability for developing food production. This zone can take
the advantage of favorable terrains to introduce ridge-furrow system with film
mulching and also develop supplemental irrigation agriculture in the flat areas under
the support of rainwater storage system. Moreover, it can ensure self-sufficient sup-
ply of food production, and provide a certain degree of crop products for the market
and accordingly achieve economic benefits.
The third zone is allocated at general terraces and the lands with a gentle slope.
It is the major component of land use. In the past, food production is in a very low
level for this zone, where for the lands are much influenced by human activities, and
Fig. 7 Dryland landscape agroecological model based on rainwater harvesting technology. This
system returned from cropland almost all in the hillside before to diverse ecosystems distributed in
a hillside, which is beneficial to increase in local farmer household income, to promote land use/
land coverage optimization, social development and regional sustainable development (Modified
from Li et al. 2003 )
Integrated Dryland Agriculture Sustainable Management in Northwest China