Effects of Different Nitrogen Application Levels on Rice Nutrient Uptake and Ammonium Volatilization

The effects of different nitrogen application levels on nutrient uptake and ammonium volatilization were studied in a field experiment with rice variety Zheyou 12 as material.The results showed that the accumulative amounts of nitrogen,phosphorus and potassium showed an increasing tendency with the increasing nitrogen application level from 0 to 330 kg/hm2.The accumulative amounts of nitrogen,phosphorus and potassium decreased when the nitrogen application level was above 270 kg/hm2.The accumulative amounts of nitrogen,phosphorus and potassium increased with organic manure addition at 150 kg/hm2 nitrogen application level.The nitrogen uptake peaked from jointing stage to heading stage,and also increased with the increasing nitrogen application level from 0 to 270 kg/hm2.The rice grain yields were positively correlated with the accumulative amounts of nitrogen,phosphorus and potassium.Among those,the accumulative nitrogen amount was most closely correlated with rice yield.Velocity and accumulative amounts of ammonium volatilization increased with the increasing nitrogen application level.Compared with other stages,faster ammonium volatilization velocity and higher ammonium accumulative amount were observed several days after the basal fertilizer was applied.Ammonium volatilization velocity at nitrogen application rate of 270 kg/hm2 and 330 kg/hm2 were far higher than those in other treatments.The ammonium nitrogen volatilization loss accounted for 23.9% of the total applied nitrogen at the nitrogen application level of 330 kg/hm2.