Abstract:

Nitrogen is the indispensable nutrient to rice production. The uptake of nitrogen are affected by varietal characteristics, fertilizer application, soil condition and environment factors. Rational application technique and nitrogen use efficiency for rice in the field have been studied by many scholars, which had a direct effect on high-yield and high-efficiency production of rice. However, all of them were studied under the same soil condition. There have been limited studies on the nitrogen use efficiency and yield under different soil conditions. In fact, the difference of soil condition consequentially results in the difference of nutrient uptake in rice under the same land tillage and management in the same region. Four rice cultivars were used to study the effects of nitrogen fertilizer on nitrogen use efficiency，yield and characters of nitrogen uptake under two soil conditions(sandy and clay soil) in soil culture pool. The results were as follows：(1) Yield of rice in sandy and clay soil was increased by nitrogen application，and that in clay soil was higher than that in sandy soil，but the effect of nitrogen on yield increment was greater in sandy soil than in clay soil. (2) Nitrogen utilization of rice was different under different soil conditions. NHI and PNUE were higher in sandy soil than in clay soil. ANRE，PFP and SNDR were higher in clay soil than in sandy soil. ANUE was varied in different cultivars under different soil conditions. (3) NHI，ANUE，PNUE，PFP and SNDR significantly were decreased with the increment of amount of nitrogen applied under two soil conditions. In sandy soil，ANRE was increased with increasing the nitrogen application and reached the highest value at high nitrogen level. However，in clay soil，ANRE was increased with increasing of the nitrogen application at first，and reached the highest value at medium nitrogen level，then decreased dramatically at high nitrogen level. (4) N uptake rate for rice straw and for rice grain and total N uptake rate for rice were higher in sandy clay soil than in sandy soil，but the difference between them was relatively little. (5) Under different soil conditions，there were significant genotypic differences in effects of applying nitrogen fertilizer on nitrogen use efficiency，yield and characters of nitrogen uptake.

Key words: Rice, Soil condition, Applying nitrogen fertilizer, Nitrogen use efficiency, Effect yield increasing, Characters of nitrogen uptake