To find optimum application rate of nitrogen under drip irrigation in the semi-arid region of Jilin province

two years (2015 - 2016) field experiments were conducted in spring maize fields mulched with plastic film to study the effects of different nitrogen application rates (0

70

140

210

280 and 350 kg/hm2) on yield

nitrogen absorption and utilization

inorganic nitrogen accumulation in soil profile (0 - 200 cm) and nitrogen balance under drip irrigation. The results indicated that maize yield increased with the increase of nitrogen application rate when the nitrogen application rate was in the range of 70 ~ 210 kg/hm2

and no significant difference was found among treatments when the nitrogen application rate was over 210kg/hm2. Based on the fitting model between maize yield and nitrogen application rate

the optimal parameter was 195.1 and 201.0 kg/hm2

respectively. Nitrogen application significantly increased nitrogen accumulation at different growth stages of maize

and the highest nitrogen accumulation showed in the treatment supplied with 210 kg/hm2 of nitrogen at the grain filling stage and the mature stage. Recovery efficiency

agronomic efficiency and partial factor productivity of nitrogen all decreased with the increasing of it application rate. At the mature stage of maize

NO3--N and NH4+-N contents both gradually reduced with the increasing depth of soil profiles (0 - 200 cm). Compared with the control

NO3--N and NH4+-N contents of 0 - 200 cm soil layers were both increased in treatments applied with nitrogen

and NO3--N contents of 40 - 200 cm soil layers in treatments supplied with 280 and 350 kg/hm2 of nitrogen were significant higher than those in other treatments. Nitrogen absorption of maize

soil inorganic nitrogen accumulation and nitrogen apparent loss were positively correlated with the nitrogen application rate

and they accounted for 21.6% ~ 23.3%

33.0% ~ 37.4% and 41.0% ~ 43.7% of the nitrogen input. Under the experimental conditions

according to the comprehensive yield

nitrogen absorption and utilization

soil inorganic nitrogen content and nitrogen balance and other factors

the appropriate amount of nitrogen fertilizer for spring maize should be controlled at 195 ~ 210 kg/hm2 under drip irrigation with plastic mulching in the semi-arid region of Jilin province.