 |
This plot shows
the very close relationship between grain yields and fertilizer application in China
between 1952 and 1993 (R > 0.98). In the 1950s, when fertilizer application was around
50 kg/ha, typical grain yields ranged between 1,200 and 1,500 kg/ha. In the early 1990s,
when more than 300 kg of chemical and organic fertilizers were applied per hectare, crop
yields were around 4,000 kg/ha.
However, this bivariant correlation probably somewhat overestimates the
relationship, because it does not take into account the important effects of other
cofactors of crop yield increases, such as irrigation, pesticide use, and other
agricultural management techniques.
Yet there can be no doubt that the increase of fertilizer application - especially the
increase of chemical fertilizer consumption - is a major factor in China's increase in
crop productivity.The data for the plot were
taken from the following source: Wang, Q. / Halbrendt, C. / Johnson, S.R. (1995):
Grain Production and Environmental Management in China's Fertilizer Economy. In: Journal
of Environmental Management, Vol. 47, 283-296. And: China Statistical Yearbook, 1998.
State Statistical Bureau, People's Republic of China, Beijing. p.393 |
