Abstract: Mid-and long-term experiment was designed to study the release rate of soil P,K and fertilizer effects under different fertilization systems at Liaohe Plain,and the process of building macro nutrients pool.The results showed that the effects of N and P fertilizer for increasing maize production were significant.But Kfertilizer had not such effects.As far as soybean was concerned,Pand Kfertilizer all had obvious effects.The difference between quantity of nutrients and yields under different fertilization treatment was similar.However,the changed extent was different.The former was greatly higher than the latter,which indicated that the increase of grain yield and nutrients exhaustion were not proportional.The ability of P-supplication in soybean fields was better than that in maize fielels.With time running after fertilization,the quantity of residual P and K that come into available nutrients pool declined,and varied with different element.

Key words: Nitric oxide, Water stress, Poplar, Chlorophyll fluorescence parameter, Protection