Abstract: The daily precipitation data from 1951 to 2002 recorded by 93 weather stations in Northeast China were used to study the temporal and spatial distribution of extreme precipitation and dryness events in this part of China, and the causes of intensifying drought and flood disasters were analyzed from the viewpoint of the changes in the frequency and strength of these events. The results showed that in last 52 years, sprinkle had an obvious decreased frequency, rainstorm had a little change of its frequency but an obvious increased intensity, severe dryness was obviously increased, while severe wetness was obviously decreased. Under the background of a little change of total precipitation, precipitation events had an obvious trend of extremeness, and the distribution of precipitation became more asymmetric, which might be one of the main causes of the higher frequency and enhanced intensity of drought and flood, and bring with negative effects on the eco-environment, and especially the agricultural production of Northeast China.

Key words: Winter wheat, Fertilizer combinations, Water-supply-demand status, Water use efficiency