Nitrogen losses under simulated rainfall conditions in rice-wheat rotation of Taihu lake watershed plain

Field trials of rainfall simulation were carried out to study effects of different rainfall intensities and nitrogen fertilizer application rates on nitrogen losses in rice-wheat rotation of Taihu Lake Watershed.It was showed that the mean concentration and accumulated amounts of runoff losses of nitrogen were highly correlated with N-application rates.With same total rainfall,runoff lasted longer under the low rainfall intensity than that under the higher one,but the total runoff amount is more under the higher rainfall intensity.While accumulated amounts of runoff losses of nitrogen under low rainfall intensity is more than that under higher rainfall intensity,which was more obvious with middle and high N-application rates.The experiment indicated that the lower rainfall intensity treatment,lasting longer time,caused more losses amounts of runoff nitrogen than that under the high rainfall intensity with same total rainfall amount.