Abstract
This study analyses the spatial distribution and interannual change in grain production in the transect along 38°N of North China Plain (NCP) by using statistical data at county level and evaluates the interrelationships among grain production, land condition including groundwater resources, climate, and socio-economic factors. The western part of the NCP shows high and stable productivity of grain production, which is highly determined by the availability of fresh water from groundwater flow system in alluvial fan. Whereas the eastern lowland shows low and unstable productivity, caused by high total dissolved solids (TDS) concentrations in shallow groundwater. The zones of the high TDS concentrations in shallow groundwater were formed at discharge areas of groundwater flow systems corresponding to geomorphologic units. In the lowland area of eastern NCP, grain productions are sensitive to climatic variation because of the low availability of fresh water. The local hydro-geomorphological and hydro-geological characteristics are the fundamental elements in understanding grain production. Secondly, grain production in every county has an increasing trend until the middle of 1990s. This corresponds to the increase in productivity per unit area owing to the improvement of agricultural technology. The stagnancy in grain productions in late 1990s suggests the influence of the cost for grain productions. The consistent steady decline of watertable will promptly raise the pumping cost. This phenomenon may become a limiting factor to grain production in the future when the ultimate level of water stress is reached.
