Effects of Nitrogen Application Level on Rice Nutrient Uptake and Ammonia Volatilization

The effects of different nitrogen application levels on nutrient uptake and ammonia volatilization were studied with the rice cultivar Zheyou 12 as a material. The accumulative amounts of nitrogen, phosphorus and potassium in rice plants across all growth stages showed a trend to increase with increasing nitrogen application levels from 0 to 270 kg/hm(2), but decreased at nitrogen application levels exceeding 270 kg/hm(2). Moreover, the accumulative uptake of nitrogen, phosphorus and potassium by the rice plants was increased by application of organic manure in combination with 150 kg/hm(2) nitrogen. The nitrogen uptake was high during the jointing to heading stages. Correlation analysis showed that rice yield was positively correlated with the accumulative uptake of nitrogen, phosphorus and potassium by the rice plants. The highest correlation coefficient observed was between the amount of nitrogen uptake and rice yield. The rate and accumulative amounts of ammonia volatilization increased with increasing nitrogen fertilizer application level. Compared with other stages, the rate and accumulative amount of ammonia volatilization were higher after base fertilizer application. The ammonia volatilization rates in response to the nitrogen application levels of 270 kg/hm(2) and 330 kg/hm(2) were much higher than those in the other treatments. The loss of nitrogen through ammonia volatilization accounted for 23.9% of the total applied nitrogen at the nitrogen application level of 330 kg/hm(2).