Abstract: A six years field experiment was conducted at the lower reaches of Liaohe River Plain to study the effects of different application rate of phosphorous (P) fertilizer on the use efficiency of applied fertilizer P, establishment of soil P pool, and the release rate of soil P. The results showed that P fertilization increased crop yield, and the yield increment of soybean was greater than that of maize. However, when the P application rate exceeded 25 kg·hm-2 per year, the yield-increasing effect was not significant. Phosphorous fertilization also increased the P uptake by crops, and the increment was higher than yield increment. When the P application rate was 25 kg·hm-2 per year, the fertilizer P use efficiency was about 30%. With the increase of P application rate, the use efficiency of fertilizer P decreased, but the proportion of soil available P transformed from residual fertilizer P increased. After the P fertilization, the transformation rate of residual fertilizer P into soil less-available P reached as high as 80%, and the proportion of the transformed soil less-available P increased with increasing P application rate, which was of significance in the establishment of soil P pool.

Key words: Exserohilum monoceras, Echinochloa crus-galli, Herbicide, Synergism, Paddy field