中国玉米小麦产量与氮肥利用效率同步提高的研究进展

Achieving both high yield and high nitrogen use efficiency (NUE) simultaneously has become a major challenge with increased global demand for food, depletion of natural resources, and deterioration of environment. As the greatest consumers of N fertilizer in the world, Chinese farmers have overused N and there has been poor synchrony between crop N demand and N supply because of limited understanding of the N uptake-yield relationship. To address this problem, this study evaluated the total and dynamic N requirement for different yield ranges of two major crops (maize and wheat), and suggested improvements to N management strategies. Whole-plant N aboveground uptake requirement per grain yield (N _req) initially deceased with grain yield improvement and then stagnated, and yet most farmers still believed that more fertilizer and higher grain yield were synonymous. When maize yield increased from < 7.5 to > 12.0 Mg ha^-1, Nreq decreased from 19.8 to 17.0 kg Mg^-1 grain. For wheat, it decreased from 27.1 kg Mg^-1 grain for grain yield < 4.5 Mg ha^-1 to 22.7 kg Mg^-1 grain for yield > 9.0 Mg ha^-1. Meanwhile, the percentage of dry matter and N accumulation in the middle-late growing season increased significantly with grain yield, which indicated that N fertilization should be concentrated in the middle-late stage to match crop demand while farmers often applied the majority of N fertilizer either before sowing or during early growth stages. We accordingly developed an integrated soil-crop system management strategy that simultaneously increases both grain yield and NUE.     

中国玉米小麦产量与氮肥利用效率同步提高的研究进展（英文）

Achieving both high yield and high nitrogen use efficiency(NUE) simultaneously has become a major challenge with increased global demand for food,depletion of natural resources,and deterioration of environment.As the greatest consumers of N fertilizer in the world,Chinese farmers have overused N,and there has been poor synchrony between crop N demand and N supply because of limited understanding of the N uptake-yield relationship.To address this problem,this study evaluated the total and dynamic N requirement for different yield ranges of two major crops(maize and wheat),and suggested improvements to N management strategies.Whole-plant N aboveground uptake requirement per grain yield(N_(re)q) initially deceased with grain yield improvement and then stagnated,and yet most farmers still believed that more fertilizer and higher grain yield were synonymous.When maize yield increased from 7.5to 12.0 Mg ha~(-1),Nreq decreased from 19.8 to 17.0 kg Mg~(-1) grain.For wheat,it decreased from 27.1 kg Mg~(-1) grain for grain yield 4.5 Mg ha~(-1) to 22.7 kg Mg~(-1) grain for yield 9.0 Mg ha~(-1).Meanwhile,the percentage of dry matter and N accumulation in the middle-late growing season increased significantly with grain yield,which indicated that N fertilization should be concentrated in the middle-late stage to match crop demand while farmers often applied the majority of N fertilizer either before sowing or during early growth stages.We accordingly developed an integrated soil-crop system management strategy that simultaneously increases both grain yield and NUE.     

Developing nitrogen management strategies under drip fertigation for wheat and maize production in the North China Plain based on a 3‐year field experiment

The intensive winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) cropping systems in the North China Plain (NCP) rely on the heavy use of mineral nitrogen (N) fertilizers. As the fertigated area of wheat and maize in the NCP has grown rapidly during recent years, developing N management strategies is required for sustainable wheat and maize production. Field experiments were conducted in Hebei Province during three consecutive growth seasons in 2012–2015 to assess the influence of different N fertigation rates on N uptake, yield, and nitrogen use efficiency [NUE: recovery efficiency (RE_N) and agronomic efficiency (AE_N)]. Five levels of N application, 0 (FN₀), 40 (FN_40%), 70 (FN_70%), 100 (FN_100%), and 130% (FN_130%) of the farmer practice rate (FP: 250 kg N ha^?1 and 205.5 kg N ha^?1 for wheat and maize, respectively), corresponding to 0, 182.2, 318.9, 455.5, and 592.2 kg N ha^?1 y^?1, respectively, were tested. Nitrogen in the form of urea was dissolved in irrigation water and split into six and four applications for wheat and maize, respectively. In addition, the treatment “drip irrigation + 100% N conventional broadcasting” (DN_100%) was also conducted. All treatments were arranged in a randomized complete block design with three replications. The results revealed the significant influence of both N fertigation rate and N application method on grain yield and NUE. Compared to DN_100%, FN_100% significantly increased the 3‐year averaged N recovery efficiency (RE_N) by 0.09 kg kg^?1 and 0.04 kg kg^?1, and the 3‐year averaged N agronomic efficiency (AE_N) by 2.43 kg kg^?1 and 1.62 kg kg^?1 for wheat and maize, respectively. Among N fertigation rates, there was no significant increase in grain yield in response to N applied at a greater rate than 70% of FP due to excess N accumulation in vegetative tissues. Compared to FN_70%, FN_100%, and FN_130%, FN_40% increased the RE_N by 0.17–0.57 kg kg^?1 and 0.03–0.34 kg kg^?1and the AE_N by 4.60–27.56 kg kg^?1 and 2.40–10.62 kg kg^?1 for wheat and maize, respectively. Based on a linear‐response relationship between the N fertigation rate and grain yield over three rotational periods it can be concluded that recommended N rates under drip fertigation with optimum split applications can be reduced to 46% (114.6 kg N ha^?1) and 58% (116.6 kg N ha^?1) of FP for wheat and maize, respectively, without negatively affecting grain yield, thereby increasing NUE.     

Changes in N leaching and crop production as a result of measures to reduce N losses to water in a 6‐yr crop rotation

The effects of various measures introduced to increase nitrogen (N)‐use efficiency and reduce N losses to water in a 6‐yr crop rotation (winter wheat, spring barley, green manure, winter wheat, spring barley, spring oilseed rape) were examined with respect to N leaching, soil mineral N (SMN) accumulation and grain yield. An N‐use efficient system (NUE) with delayed tillage until late autumn and spring, direct drilling of winter wheat, earlier sowing of winter and spring crops and use of a catch crop in winter wheat was compared with a conventional system (CON) in a field experiment with six separately tile‐drained plots in south‐western Sweden during the period 1999–2011 (two crop rotation cycles). Total leaching of NO₃‐N from the NUE system was significantly 46 and 33% lower than in the CON system during the first and second crop rotation cycle, respectively, with the most pronounced differences apparently related to management strategies for winter wheat. Differences in NO₃‐N leaching largely reflected differences in SMN during autumn and winter. There was a tendency for lower yields in the NUE system, probably due to problems with couch grass. Overall, the measures for conserving N, when frequently used within a crop rotation, effectively reduced NO₃ concentrations in drainage water and NO₃‐N leaching losses, without severely affecting yield.     

种植密度对冬小麦氮素吸收利用和分配的影响

为了探讨实现冬小麦籽粒产量与氮素利用效率协同提高的途径,为制定高产、高效栽培管理措施提供理论依据,在大田条件下,以大穗型小麦品种"泰农18"和中穗型小麦品种"山农15"为试验材料,根据品种特性分别设置4个种植密度("泰农18":135万苗.hm 2、270万苗.hm 2、405万苗.hm 2和540万苗.hm 2;"山农15":172.5万苗.hm 2、345万苗.hm 2、517.5万苗.hm 2和690万苗.hm 2),研究了种植密度对籽粒产量、氮素吸收积累和运转分配、氮素利用效率以及土壤中硝态氮、铵态氮和无机态氮总积累量的影响。研究结果表明,随种植密度增加,两种穗型冬小麦品种成熟期植株氮素积累量、籽粒产量、氮肥吸收利用效率和氮肥偏生产力均表现为先增加后降低,籽粒氮积累量、氮素收获指数和籽粒氮含量下降,花前营养器官氮素转运量和对籽粒氮的贡献率升高。随种植密度的增加,"泰农18"的氮素利用效率随密度的增大先增大后减小,"山农15"随密度的增大而减小。土壤中硝态氮、铵态氮和无机态氮总积累量随密度增加而降低。在本试验条件下,"泰农18"和"山农15"兼顾高产和高效利用氮素的适宜种植密度分别为270万苗.hm 2和345万苗.hm 2。     

EFFECT OF NITROGEN MANAGEMENT ON PRODUCTIVITY,NITROGEN USE EFFICIENCY AND NITROGEN BALANCE FOR A WHEAT-MAIZE SYSTEM

Over-application of nitrogen (N) in North Central China is primary reasons for yield restriction and low nutrient use efficiencies. This study was to determine N management practices on grain yield, N efficiency, and N balance in China. Results from four season crops indicated that no significant yield differences across different N rates for the first season wheat were observed. Treatments with N rates lower than 75 kg N ha^?1 manifested yield reduction for the following seasons, and no much yield differences existed for the rest treatments. The accumulated N recovery efficiency (NREac) values ranged from 10.1% to 44.2% over the four seasons, and over N fertilization led to low NREac. The net N balance increased with N applied. Results from current study provided the proof that in the current rotation system the N₁₅₀N₁₅₀ treatment was the best economic treatment for achieving both higher yield and N use efficiency.     

秸秆覆盖与氮肥运筹对杂交稻根系生长及氮素利用的影响

【目的】在我国稻-麦、稻-油等多熟制区域,富含氮素的小麦、油菜等水稻前茬作物秸秆被大量弃置、焚烧,造成极大浪费和环境污染,与此同时,稻季氮肥投入量却在逐年增加,因此在水稻生产中研究秸秆覆盖与氮肥配合施用的理论与技术,对实现秸秆还田与减少氮肥用量具有重要意义。本试验研究油菜、小麦2种秸秆覆盖方式下,3种不同的氮肥运筹方式对杂交稻主要生育时期根系生长、氮素吸收利用特征及产量的影响,并探讨其根系生长与氮素利用及产量间的关系,以期寻求最佳的秸秆还田与氮肥运筹搭配模式。【方法】本试验以杂交稻F优498为材料,采用两因素裂区试验设计,主区为小麦秸秆覆盖(S1)、油菜秸秆覆盖(S2)和无秸秆覆盖(S0);副区为氮肥运筹模式,在135 kg/hm2总施氮量条件下,设置基肥∶蘖肥∶穗肥为5∶3∶2(N1);基肥∶蘖肥∶穗肥为3∶3∶4(N2);基肥∶蘖肥∶穗肥为3∶1∶6(N3)3种氮肥运筹模式,以不施氮肥(N0)为对照。研究各处理杂交稻在移栽后20 d、移栽后30 d、齐穗期和成熟期根系生长及形态、各生育期的干物质与氮素积累,水稻茎鞘的干物质转运、产量及其构成因子以及各时期氮素积累及利用效率,同时对各生育时期根系生长与氮素利用及产量间的关系进行分析。【结果】结果表明,小麦秸秆覆盖均可有效促进杂交稻各生育时期的根系生长、改善根系形态、增加各时期的干物质与氮素积累,提高氮肥的利用效率及稻米产量。在不同种类秸秆覆盖下,基肥∶蘖肥∶穗肥(倒4叶龄期施入)为3∶3∶4(N2)时,可及时地对杂交水稻主要生育时期的根系生长进行调控,有效促进抽穗至成熟期的干物质积累与转运率,提高水稻主要生育时期的氮素积累及氮肥利用效率,显著增加稻谷产量,为本试验中最优的氮肥管理模式;而氮肥后移比例过高(基肥∶分蘖肥∶穗肥运筹比例为3∶1∶6),会限制齐穗期根系的生长,导致稻谷产量及氮肥利用效率降低。相关性分析表明,秸秆覆盖与氮肥运筹下主要生育时期根干重、根体积、总根长与产量及氮素吸收利用均存在显著或极显著的正相关(r=0.38*0.78**),尤其以齐穗期的根体积与总根长、根干重与氮素累积、产量及氮素回收利用率的相关性最好。【结论】小麦秸秆、油菜秸秆覆盖能够有效促进杂交稻根系的生长,增加干物质与氮素积累,提高氮肥利用效率,且小麦秸秆覆盖效果更显著。秸秆覆盖条件下,氮肥运筹以基肥∶蘖肥∶穗肥为3∶3∶4时的水稻根系生长旺盛,物质生产能力强,氮肥利用效率最高。因此,小麦秸秆覆盖与基肥∶蘖肥∶穗肥以3∶3∶4的比例配合的水稻的产量最高,为最优组合。     

Optimizing nitrogen management strategy under wheat straw incorporation for higher rice production and nitrogen use efficiency

Nitrogen (N) application plays an important role in rice production. Limited attention has already been paid to optimizing N fertilizer management strategy for higher grain yield and nitrogen use efficiency (NUE) of rice with crop residue incorporation. Field experiments were conducted with the objective to determine the response of several N application methods to rice production and to evaluate their NUE. Three N fertilizer application methods, i.e., local farmers' N fertilizer practice (FNP), modified farmers' N fertilizer practice (MNP), and increased the amount of N fertilizer practice (INP), were adopted with zero N application as control (CK). The results showed that, compared with that under FNP, grain yield was significantly higher under MFP, owing to signficantly enhanced total spikelets as a result of more panicles per unit area. Relative to FNP, MNP markedly increased nitrogen agronomic efficiency (AE_N), nitrogen recovery efficiency (RE_N), nitrogen physiological efficiency (PE_N) and nitrogen partial factor productivity (PFP_N), but AE_N, PE_N and PFP_N of INP were significantly lower. Further analysis showed that the number of tiller, leaf area index, aboveground biomass, SPAD value, plant N content and N uptake at the early vegetative stage were improved significantly under MNP compared to those under FNP, contributing to higher total aboveground biomass and total N uptake.     

硝化抑制剂影响小麦产量、N2O与NH3排放的研究

通过田间小区试验研究不同施氮水平下,施用硝化抑制剂CP对小麦产量、氮素利用率、氧化亚氮(N_2O)排放与氨(NH_3)挥发的综合影响规律。结果表明:在施氮水平为140 kg/hm2与180 kg/hm2时,施用CP促使小麦产量分别显著增加17.8%和15.4%,在同一施氮水平下,施用CP促进小麦氮素利用率提高11.3%~25.2%。施用硝化抑制剂CP可以降低麦季(特别是基肥与穗肥施用时期)土壤N_2O的排放速率,并显著减少39.3%~53.7%的累积N_2O排放量。但是在两个施氮水平下,施用CP导致麦季NH_3挥发量增加1.46~1.75倍,而且此效应主要发生于基肥与穗肥观测期。本研究说明:在麦季施用硝化抑制剂CP可以提高氮素利用率,从而提高小麦产量,并且能减少N_2O排放,但同时会导致一定程度的NH_3挥发增加,需加以控制。     

Integrated agronomic practice management decreases soil carbon emission and increases environmental ecological benefits of summer maize

Integrated agronomic practice management (IAPM) is an effective strategy for increasing nitrogen (N) use efficiency (NUE) and yield during crop production. Although various studies have evaluated the mechanism of a single agronomic management practice to increase yield and production efficiency and decrease environmental costs, few have investigated the effects of IAPM systems. A field experiment was conducted using four IAPM systems, a local smallholder farmers’ practice system (T1), an improve...     

氮、硫配施对冬小麦氮素利用效率及产量的影响

【目的】氮(N)、硫(S)是生物所必需的营养物质,对小麦籽粒产量和品质起着重要作用。硫素供应不足,特别是在当前大量氮素供应情况下引起的作物生理性缺硫将导致作物产量和含硫氨基酸蛋白质含量下降。本文旨在探索氮、硫配施对冬小麦氮素利用效率和籽粒产量的促进效果并提出合理的区域氮、硫施肥技术。【方法】20122013年,在河南温县以国审冬小麦品种豫麦49-198为供试材料,进行大田试验。设置不同施氮量0、120、180、240和360 kg/hm2(分别以N0、N120、N180、N240和N360表示)和施硫0和60 kg/hm2(S0和S60)试验,调查氮、硫对冬小麦干物质积累、氮素积累分配、籽粒产量和氮素利用效率的影响。【结果】对冬小麦生育后期干物质积累分析表明,干物质积累随施氮量增多而提高,相同施氮量条件下施硫较不施硫小麦干物质积累量显著提高,其中成熟期干物质积累量N180S60、N240S60和N360S60分别较N180S0、N240S0和N360S0提高2225、3607和3120 kg/hm2,而且氮素低的处理添加硫后干物质积累量高于氮素高不加硫处理,如N180S60N240S0、N240S60N360S0,处理间差异均达显著水平。随施氮量增多,冬小麦植株氮素积累总量增加,在N 240和360 kg/hm2水平,硫素供应显著增加小麦植株氮素积累。不同施氮量条件下施硫较不施硫均显著提高了小麦籽粒产量,分别提高了10.5%、18.3%、5.2%、5.6%和4.9%。随施氮量增多,氮肥偏生产力下降,氮回收效率、生理效率和农学效率则均以N 180达最高值。不同施氮水平下,施硫均显著提高了冬小麦氮素回收效率,但对氮生理效率影响不显著,其中在施N量为120、180和240kg/hm2时,施硫较不施硫氮肥偏生产力和农学效率均显著提高。【结论】在当前小麦生产中,采用控氮或减氮增硫技术措施,可实现小麦氮利用效率和籽粒产量的同步提高。在本试验地区小麦生产中,达到冬小麦稳产高效或增产高效的适宜施氮量为180 240 kg/hm2配合60 kg/hm2硫肥施用。     

Choice of nitrogen fertilizer affects grain yield and agronomic nitrogen use efficiency of wheat cultivars

Abstract

Nitrogen use efficiency (NUE) is low in cereals especially in wheat. Different wheat cultivars may vary in NUE due to inherited biological nitrification inhibition (BNI) potential. In this study, three wheat cultivars (Punjab-2011, ARRI-2011 and Millat-2011) were fertilized at the rate of 140?kg ha^?1 with three N sources [nitrophos (NP), urea and calcium ammonium nitrate (CAN)]. The soil nitrate (NO₃^?)-N contents were significantly enhanced coupled with simultaneous decrease in ammonium (NH₄⁺)-N contents in the rhizosphere of cultivar Punjab-2011, fertilized with NP; however, cultivar Millat-2011 receiving urea behaved in contrast. Wheat cultivar Punjab-2011 fertilized with NP had the highest grain yield and agronomic NUE than other treatments due to significant increase in chlorophyl contents, allometric and yield parameters. The highest net benefit was recorded from the cultivar Punjab-2011 fertilized with CAN. In conclusion, use of NP in Punjab-2011 enhanced the grain yield and agronomic NUE.     

Agronomic Assessment of Nitrogen Use Efficiency in Spring Wheat and Interrelations with Leaf Greenness Under Field Conditions

Four spring wheat genotypes (Triticum aestivum L.) were grown without (N0 = 0 kg N ha^?1) and under ample (N1 = 250 kg ha^?1) nitrogen (N) fertilizer in field experiments in two seasons. The aim was to assess genotypic variation in N use efficiency (NUE) components and N-related indices during grain filling thus to identify superior wheat genotypes. Leaf chlorophyll (SPAD) readings at crucial growth stages were employed to help differentiate genotypes. Interrelations between yield and N-related indices with SPAD, where also assessed to explain possible pathways of improving NUE early in the growing season. Results showed that genotypic effects on NUE were mostly evident in 2000, a year with drier preanthesis and wetter postanthesis than the normal periods. ‘Toronit’ almost always had the highest biomass yield (BY) and grain yield (GY). Except in 1999 under N0, ‘L94491? showed the highest % grain N concentration (GNC). Genotypes affected SPAD at almost all stages and N fertilization delayed leaf senescence for all genotypes and growth seasons. Correlations between SPAD at different growth stages and GY, N biomass yield at maturity (NBYM) and GNC were significant (P≤ 0.001), positive and strong/very strong (>r = 0.7). N translocation efficiency (NTE) was inversely related to PANU (~r = ? 0.77, P≤ 0.001), suggesting that N after anthesis is being preferentially transported to the ears to meet the N demand of the growing grains. It is concluded that there is still a large potential for increased NUE by improved N recirculation, use of fast and inexpensive crop N monitoring tools and high yielding, N uptake efficient genotypes.

Abbreviations: NUE, Nitrogen use efficiency; SPAD, Minolta SPAD-502 chlorophyll meter, NHI, nitrogen harvest index; HI, Harvest index; NTE, N translocation efficiency from vegetative plant parts to grain; DMTE, dry matter translocation efficiency; CPAY, contribution of pre-anthesis assimilates to yield; PANU, Post-anthesis N uptake, d.a.s., days after sowing, N0, zero (0) kg ha^?1 applied N fertilizer, N1, 250 kg ha^?1 applied N fertilizer.     

Timing and Method of 15Nitrogen-Labeled Fertilizer Application on Grain Protein and Nitrogen Use Efficiency of Spring Wheat

ABSTRACT

Grain protein content is one of the most important quality constraints for bread wheat (Triticum aestivum L.) production in eastern Canada. A field experiment was conducted for two years (1999 and 2000) on the Central Experimental Farm, Ottawa, Canada, to study whether split application of nitrogen (N) fertilizer improved grain protein content and nitrogen-use efficiency (NUE). Two cultivars (‘Celtic,’ as N-responsive and ‘Grandin’, as N-non-responsive) were grown using three different N doses and application methods: (1) 100 kg N ha^?1 as NH₄NO₃, soil-applied at seeding with ¹⁵N₂-labeled NH₄NO₃ to microplots, (2) 60 kg N ha^?1 soil-applied at seeding plus 40 kg N ha^?1 foliar-applied at the boot stage with ¹⁵N₂-labeled urea to microplots, and (3) 90 kg N ha^?1 as soil-applied at seeding plus 10 kg N ha^?1 foliar-applied at the boot stage with ¹⁵N₂-labeled urea to microplots. Plants were sampled at heading and maturity. While dry-matter production and grain yields were not affected by the treatments in either year, N application methods influenced tissue N concentration and NUE. In 1999, extended drought stress led to significant yield reduction; in 2000, foliar application of 10 kg N ha^?1 at the boot stage significantly increased grain N concentration when grain protein was under the limit for bread quality, suggesting that later-applied N can contribute to grain protein content. At maturity, the average NUE was 22.3% in 1999 and 34.5% in 2000, but was always greater when all N was applied at seeding (42.5%) than when N was foliar-applied at the boot stage (18.5% to 24.5%). We conclude that application of a small amount of fertilizer N at the boot stage can improve the bread-making quality of spring wheat by increasing grain protein concentration.     

Effect of nitrogen rate on plant nitrogen loss in winter wheat varieties 1

Gaseous nitrogen (N) loss from winter wheat (Triticum aestivum L.) plants has been identified, but has not been simultaneously evaluated for several genotypes grown under different N fertility. Two field experiments were initiated in 1993 and 1994 at the Agronomy Research Station in Stillwater and Perkins to estimate plant N loss from several cultivars as a function of N applied and to characterize nitrogen use efficiency (NUE). A total of five cultivars were evaluated at preplant N rates ranging from 30 to 180 kg·ha^‐1. Nitrogen loss was estimated as the difference between total forage N accumulated at anthesis and the total (grain + straw) N at harvest. Forage, grain, straw yield, N uptake, and N loss increased with increasing N applied at both Stillwater and Perkins. Significant differences were observed among varieties for yield, N uptake, N loss, and components of NUE in forage, grain, straw, and grain + straw. Estimates of N loss over this two‐year period ranged from 4.0 to 27.9 kg·ha^‐1 (7.7 to 59.4% of total forage N at anthesis). Most N losses occurred between anthesis and 14 days post‐anthesis. Avoiding excess N application would reduce N loss and increase NUE in winter wheat varieties. Varieties with high harvest index (grain yield/total biomass) and low forage yield had low plant N loss. Estimates of plant loss suggest N balance studies should consider this variable before assuming that unaccounted N was lost to leaching and denitrification.     

Yield and nitrogen use efficiency of wheat increased with root length and biomass due to nitrogen,phosphorus, and potassium interactions

Balanced applications of nitrogen (N), phosphorus (P), and potassium (K) are known to increase grain yield of wheat but the impact of the interactions among N, P, and K on root growth and nitrogen use efficiency (NUE) have not been proven. The aim of this study was to investigate the effect of balanced applications of N, P, and K on the rooting patterns and NUE of wheat. Two glasshouse experiments were conducted. A rhizobox study was used to assess the impact of interactions among N, P, and K fertilisers on total root length, biomass, specific root length, root length density, N use efficiency (NUE), and N uptake efficiency of the shoots (NUpE_shoot) and N nutrition index. In a separate pot study, plants were grown to maturity to confirm the effect of the observed changes in root growth on NUE, NUpE_grain, and grain/biomass yield. In the rhizobox experiment when plants were supplied with N+P+K, total root biomass increased approximately six‐fold relative to plants grown with N alone or with no fertiliser. Plants exposed to N+P+K had NUpE_shoot and NUE values that were five and ten times higher, respectively, than plants that received just fertiliser N. Plants supplied with N+P or N+P+K had N nutrition indices close to one (N‐adequate), while plants that only received N had an index of 0.62 (N‐deficient). The pot study confirmed that the changes in root length and biomass in plants exposed to N+P+K resulted in significant increases in NUE, NUpE_grain, shoot biomass, and grain yield at maturity. Interactions among fertiliser N, P, and K played a critical role in influencing root biomass and length, which was associated with increases in NUE, NUpE_shoot and NUpE_grain.     

Winter wheat fertilizer nitrogen use efficiency in grain and forage production systems

Abstract

Nitrogen use efficiency (NUE) is known to be less than fifty percent in winter wheat grain production systems. This study was conducted to determine potential differences in NUE when winter wheat (Triticum aestivum L.) is grown strictly for forage or grain. The effects of different nitrogen rates on plant N concentrations at different growth stages and on grain yield were investigated in two existing long‐term winter wheat experiments near Stillwater (Experiment 222) and Lahoma (Experiment 502), OK. At both locations in all years, total N uptake was greater when wheat forage was harvested twice (Feekes 6 and flowering) compared to total N uptake when wheat was grown only for grain. Percent N content immediately following flowering was much lower compared to percent N in the forage harvested prior to flowering, indicating relatively large losses of N after flowering. Averaged over locations and years, at the 90 kg N ha^?1 rate, wheat produced for forage had much higher NUE (82%) compared with grain production systems (30%). While gaseous N loss was not measured in this trial, the higher NUE values found in the forage production systems were attributed to harvesting prior to anthesis and the time when plant N losses are known to be greater.     

Grain yield,nitrogen use efficiency and tillage intensity in wheat as affected by precision nutrient management

ABSTRACT

The present studies were conducted to evaluate the effect of different nutrient management practices under two tillage options in wheat. The experiments were laid out in split-plot design with a combination of two varieties (WH 1105 and HD 2967) and two tillage options (Conventional and No tillage) in the main plot and six precision nutrient management practices [absolute control, site-specific nutrient management with Nutrient Expert for wheat (SSNM-NE)(170 kg nitrogen (N)/ha), SSNM NE+GreenSeeker (GS)(153/158 N kg/ha), N₁₂₀ (120 kg N/ha) before irrigation, N₁₂₀ after irrigation and N Rich (180 kg N/ha)] in subplot replicated thrice. The grain yield and quality characters in no tillage (NT) and conventional tillage (CT) were similar but agronomic efficiency was higher in NT. Both the varieties (WH 1105 and HD 2967) gave similar grain yield and quality. Wheat variety WH 1105 recorded significantly higher sodium dodecyl sulfate sedimentation (SDS) and gluten index. The treatment SSNM NE+GS had resulted in 107.1% higher grain yield than no nitrogen control but similar to enriched N plot (180 kg N/ha). The grain protein, SDS and gluten index in need-based nutrient management (SSNM+GS) treatment were found to be similar as recorded in SSNM-NE (170 kgN/ha) and N enriched plot (180 kg N ha^?1). The agronomic efficiency and recovery efficiency in SSNM+GS were also better than SSNM NE.     

黄土高原南部旱地冬小麦生长期N2O排放特征与基于优化施氮的减排方法研究

为了解陕西黄土高原南部旱地冬小麦季N2O排放规律,探索旱地N2O减排方法,采用密闭式静态箱法,以不同施氮处理[CK:对照,不施氮;CON:当地农民习惯施氮,施氮量220 kg·hm-2;OPT:优化施氮加秸秆还田,施氮量150 kg·hm-2;OPT+DCD:优化施氮加秸秆还田,同时施用施氮量5%的硝化抑制剂DCD;OPT(SR):优化施氮(所用肥料为包膜型缓控释肥)加秸秆还田]为基础,研究黄土高原南部旱地冬小麦农田N2O季节排放特征和减排措施。结果表明:黄土高原南部旱地冬小麦季N2O排放具有首月持续、大量排放,末月雨后瞬间排放,中期低排放的特点。各处理中,OPT+DCD和OPT(SR)在播种—返青期能显著减少N2O排放水平,而返青—成熟期,各优化处理差异不显著。从整个小麦季N2O排放总量来看,各优化处理能够减少N2O排放量,提高作物产量,降低单位产量N2O排放量。具体表现为:1与CON处理的N2O排放量相比,OPT、OPT+DCD和OPT(SR)处理分别减排29.2%(P0.01)、38.7%(P0.01)和39.3%(P0.01),但3个优化处理间差异不显著;2与CON处理的产量相比,OPT、OPT+DCD和OPT(SR)处理分别增产3.8%(P0.05)、15.2%(P0.05)和9.5%(P0.05);3与CON处理的单位产量N2O排放量相比,OPT处理单位产量N2O排放量减少31.7%(P0.05);而相对于OPT处理,OPT+DCD处理和OPT(SR)处理分别减少了单位产量排放量的22.1%(P0.05)和18.9%(P0.05)。本研究表明,减少施氮量至150 kg·hm-2,并施用秸秆是减少N2O排放的重要手段,而施用缓控释肥或一定量的DCD可提升作物产量。     

ENHANCING NITROGEN USE EFFICIENCY BY COMBINATIONS OF NITROGEN APPLICATION AMOUNT AND TIME IN WHEAT

Nitrogen (N) is one of the most important impact factors on development and growth of wheat. In this study the effects of nitrogen use efficiency on quantity and quality of grains were studied by agronomic management of N fertilizers on spring wheat (Triticum aestivum L.) grown under field conditions for two years. The experiments were performed at 16 combinations of N application amount and time, including four levels of N at 0, 60, 120 and 180 kg N ha^?1 that were used as pre-plant fertilizers, sub-treated with four levels of the same N amount used as top-dress fertilizers. As a result, with an increase in total N fertilizers, grain yield increased in a cubic equitation, but partial factor productivity (PFP_N, kg grain yield per kg N applied) decreased exponentially. With total fertilizers, N content and accumulation in vegetative tissues and grains increased linearly, but N uptake efficiency (UtE_N, kg nutrient taken up per kg N applied) decreased exponentially. When N was over-applied (>360 kg N ha^?1 in this study), grain yield clearly declined, due to decrease in productivity from per unit N. The high N level (240～300 kg N ha^?1), the reasonable distribution between pre-plant and top dress from the same amount N fertilizer not only increased grain yield but also enhanced N use efficiency.