Effects of nitrogen reduction time on rice yield,nitrogen use efficiency and fate of fertilizer nitrogen
In order to investigate the effects of nitrogen reduction time on rice yield,nitrogen use efficiency and fate of nitrogen fertilizer,and to provide a theoretical support for formulating scientific and reasonable nitrogen reduction practice in the rice production.A field experiment was conducted during 2018-2019 and a 15N micro-plot experiment was set up in 2019.Five treatments were included:(1)no nitrogen fertilizer(N0);(2)conventional fertilization(N1,N 225 kg/hm2,basal-tillering-panicle fertilizer=N 90-67.5-67.5 kg/hm2);(3)basal nitrogen reduction(N2,N 202.5 kg/hm2,basal-tillering-panicle fertilizer=N 67.5-67.5-67.5 kg/hm2);(4)tillering nitrogen reduction(N3,N 202.5 kg/hm2,basal-tillering-panicle fertilizer=N 90-45-67.5 kg/hm2);(5)panicle nitrogen reduction(N4,N 202.5 kg/hm2,basal-tillering-panicle fertilizer=N 90-67.5-45 kg/hm2).The results showed that reducing current nitrogen rate by 10%could still maintain rice yields,compared with the N1 treatment.Whereas,nitrogen reduction times had significant effects on rice yields,and N2 treatment increased rice yields by 7.8%-9.4%,compared with N3 treatment.The N2 and N3 treatments significantly enhanced the nitrogen apparent recovery efficiency and nitrogen partial factor productivity,compared with N1 treatment,while there was no significant difference in nitrogen use efficiency between N1 and N4 treatments.Compared with N4 treatment,both N1 and N2 treatments significantly increased the uptake of 15N labelled fertilizer by rice plant.The 15N use efficiencies in nitrogen fertilized treatments were 26.0%-30.1%,of which N2 treatment was significantly higher than that of N4 treatment.The 15N-fertilizer mainly remained in 0-20 cm soil layer,accounting for about 90%of the total 15N residue.Basal nitrogen reduction(N2 treatment)could improve the 15N use efficiency and residue rate,and reduce the nitrogen loss in paddy soils.In conclusion,reducing the nitrogen application rate should reduce the basal nitrogen rate,which can not only ensure rice yield,and also improve the nitrogen use efficiency and reduce nitrogen loss in rice production.
ricenitrogen fertilizer reductionrice yieldnitrogen use efficiency15N isotope tracer
NETL
NSTL
万方数据
