| The tow years location test field experiment was carried out to study the effects of nitrogen application on yield, environment, soil nitrogen supplying capacity, nitrogen and biomass accumulation and translocation characteristics, nitrogen metabolism and simplified nitrogen application technology of slow-release nitrogen fertilizer combined with urea in Sci-tech Park (35.17(?),114.14(?) of Hebi Agricultural Academy in Henan Provience. Main conclusions were:1. The wheat and maize yields were increased linearly firstly and then kept stable with the increasing of nitrogen amount. The suitable amount of nitrogen fertilizer application of wheat and maize should be270.0kg/hm2and318.7kg/hm2, respectively, to generate the highest yield. The nitrogen uptake showed a linear variation, nitrogen use efficiency and agronomy efficiency of winter wheat showed a parabola change, while the two efficiencies were decreased in maize with the increasing of nitrogen amount. In the same harvested time, nitrate nitrogen accumulation in the same soil layer was increased and the difference between different treatments was increased following with crops for rotation going on. When nitrogen fertilizer application rate more than270kg/hm2, the soil nitrate nitrogen not only obviously accumulated in the0-100cm depth, but also in deeper layer. The results of N equilibrium analysis showed that Nmin was the main N surplus at low N application, whereas apparent N loss was the main N surplus at high N application. When the nitrate nitrogen was controlled in165kg/hm2in the0-100cm depth, it would get high yields given consideration of environment safety. The nitrogen application rate of wheat was247.3kg/hm2and maize was230.6kg/hm2. The total yield of wheat and maize was21736.1kg/hm2in the rotation cycle.2. Under high soil fertility in the experiment, soil showed relatively high nitrogen supplying capacity. When there was no nitrogen application, summer maize yield was higher than wheat. Wheat yield was80.1%-86.2%of control and maize yield was60.9%-71.2%of control when no nitrogen applied. The crop yield declined over time when there was no nitrogen applied. It indicated that soil nitrogen supplying capacity was reduced. Soil nitrogen supplying capacity could be improved by increasing nitrogen application, but over-application of N could lead to Nmin accumulation and environmental risk. Our results showed that N fertilizes rate should be270kg/hm2to keep high soil nitrogen supplying capacity and achieve sustainable crop yields. 3. In continuous nitrogen application condition of the winter wheat-summer maize high-yield rotation, With nitrogen application rate increased, nitrogen accumulation in vegetative organs and grain of winter wheat and summer maize were both increased, nitrogen distribution ratio in leaf ratio showed decreased trend in mature period; both transfer rate and contribution ratio to grain of winter wheat nutrition organs were increased, respectively range from108.86kg/hm2to161.19kg/hm2,73.80-79.55%, and the transfer rate decreased gradually, range from74.72%to66.15%; ratio of vegetative organs dry matter accumulation contribution to grain decreased gradually, range from45.37%to26.11%, before winter wheat anthesis; nitrogen requirement rate (N) of100kg grain was increased, and the highest requirement was2.95g which increased by18.1%compared to control. In summer maize maturity stage, nitrogen distribution ratio in grain and leaf were decreased trend, and reduced scope was7.4%and13.9%, compared to no nitrogen application treatment, respectively, however, it was increased in stem in which the highest ratio was26.26%, and increased by41.3%compared to control; nitrogen accumulation and translocation were increased in vegetative organs, after silking, nitrogen transport rate and contribution to grain were decreased in vegetative organs. They were reduced23.7%and29.7%, compared to no nitrogen application treatment, respectively; dry matter distribution ratio to vegetative organ was increased and the highest ratio was25.61%which was3.9-fold higher than control after silking, however, the distribution ratio to grain was decreased with the lowest ratio of72.95%which reduced22.0%compared to control; nitrogen requirement rate (N) of100kg grain was increased, and the highest requirement was1.89g which increased by17.4%compared to control. When grain yield of winter wheat-summer maize rotation was more than22500kg/hm, nitrogen accumulation of winter wheat and summer maize were271.15kg/hm2,236.95kg/hm2, dry matter accumulation of winter wheat and summer maize were21044.71kg/hm2,24972.83kg/hm2, respectively, in mature period; Nitrogen transport rate of vegetative organs was159.81kg/hm2, nitrogen transport ratio of vegetative organs and nitrogen contribution ratio from vegetative organs nitrogen to grain were respectively69.64%,79.55%, dry matter transport rate of vegetative organs was2731.62kg/hm, dry matter transport ratio of vegetative organs and dry matter contribution ratio from vegetative organs dry matter to grain were respectively19.59%,27.78%, after winter wheat flowering; Nitrogen transport amount of vegetative organs was42.39kg/hm2, nitrogen transport ratio of vegetative organs and nitrogen contribution ratio from vegetative organs nitrogen to grain were respectively31.80%,29.03%, dry matter accumulation was16325.62kg/hm2, distribution ratio of vegetative organs and grain derived dry matter accumulation were16.95%,83.05%respectively, after summer maize silking; Requirement rate (N) of100kg grain of winter wheat and summer maize was2.76kg,1.75kg, respectively.4. Nitrogen application significantly increased soluble protein content, chlorophyll content, photosynthetic electron transport relative rate, NR and GS activity of winter wheat and summer maize leaf. In every growth period of winter wheat and summer maize, with nitrogen application rate increased, total nitrogen content, soluble protein content, chlorophyll content, nitrate nitrogen and ammonium nitrogen content, NR and GS activity and photosynthetic electron transport rate relative rate of winter wheat and summer maize leaf were increased. When nitrogen application rate was more than210kg/hm2, leaf chlorophyll content and GS activity winter wheat leaf were no significant difference. When nitrogen application rate was more than270kg/hm2, soluble protein content and nitrate nitrogen content of winter wheat leaf did not reached significant difference level. When nitrogen application rate was more than270kg/hm, function leaf total nitrogen content had no significant differences before silking of summer maize, in summer maize after silking stage, leaf nitrate nitrogen content were maintained a higher level. When nitrogen application rate was more than330kg/hm2, chlorophyll content of summer maize leaf had no significant difference.5. In continuous nitrogen application condition of the winter wheat-summer maize high-yield rotation, results of simplified fertilization indicated:in winter wheat season, compared with conventional urea application in one base and three topdressing mode (CK1),100%slow release urea (T1) in one base and one topdressing mode showed that there were no significant influence on yield, aboveground portion nitrogen accumulation rate, nitrogen use efficiency and nitrogen agronomic efficiency; in summer maize, yield, aboveground portion nitrogen accumulation rate, nitrogen use efficiency and nitrogen agronomic efficiency in treatments of100%slow release urea (T1),80-20slow release-conventional urea combination (T2) and60-40slow release-conventional urea combination (T3) were higher than CK1, with the highest in the treatment of T2. Inorganic nitrogen concentrations of winter wheat in treatment of T1was higher than CK1at the after filling stage. In summer maize, Inorganic nitrogen concentrations in treatment of T2 was also higher than other treatments at the silking-15d. yield, aboveground portion nitrogen accumulation rate, nitrogen use efficiency and nitrogen agronomic efficiency of T2and T1were higher than CK1, and yields of winter wheat-summer maize in the two treatments were up to22500kg/hm2, it realized the target of high yield and high efficiency and simplified fertilization in winter wheat-summer maize rotation system. |
PDF Full Text Request