Determining a critical nitrogen dilution curve for sugarcane

Adequate measurements of the nitrogen (N) concentration in the aboveground biomass of sugarcane throughout the growth cycle can be obtained using the critical N dilution curve (CNDC) concept, which provides an N‐nutrition index (NNI). The aim of this work was to determine the CNDC value for Brazilian sugarcane variety SP81‐3250, establish the critical concentration of N, and determine the NNI in the aboveground biomass throughout the cane plant and first ratoon crop cycles. The study was performed in three experimental areas located in São Paulo, Brazil, during the crop cycles of 2005/2006 (18‐month cane plant) and 2006/2007 (first ratoon). The plant cane crop was fertilized with treatments of 40, 80, or 120 kg N ha^–1 and a control treatment without N. After the plant cane harvest, rates of 0, 50, 100, or 150 kg N ha^–1 were applied to the control plot and the 120 kg N ha^–1–treatment plot in a split‐plot experimental design with four repetitions. Throughout both sugarcane cycles, measurements of aboveground biomass were used to determine the dry‐mass (DM) production and N concentration for each treatment. CNDC varied between the growth cycles, with a higher N concentration observed in the initial stages of the first ratoon and a lower N dilution observed throughout the plant cane cycle. The NNI value indicated excessive N storage in the initial stages and limiting concentrations at the end of the growth cycle. CNDC and NNI allow for the identification of the N‐nutrition variation rate and the period in which the nutrient concentration limits the production of aboveground biomass. The equations for the critical N (Ncr) level obtained in this study for plant cane (Ncr = 19.0 DM^–0.369) and ratoons (Ncr = 20.3 DM^–0.469) can potentially be used as N‐nutritional diagnostic parameters for sugarcane N nutrition.     

基于叶面积指数构建滴灌玉米营养生长期临界氮稀释曲线

明确宁夏引黄灌区基于叶面积指数(leaf area index,LAI)的滴灌玉米临界氮稀释曲线模型及其适用性,探讨以氮营养指数(nitrogen nutrition index,NNI)为监测指标对滴灌水肥一体化模式下玉米氮素营养状况诊断的可行性。该研究于2017-2018年开展了不同施氮量(0~450 kg/hm^2)下4个田块的试验,采用系统分析和统计建模的方法,分析了LAI和植株氮浓度(plant nitrogen concentration,PNC)的定量关系,构建和验证基于LAI的临界氮稀释曲线模型,并建立理论框架,将基于LAI的临界氮曲线与基于植株干物质(plant dry matter,PDM)的临界氮浓度曲线关联,比较基于LAI和PDM的临界氮曲线之间的差异。结果表明,玉米营养生长期临界氮和LAI符合幂函数关系,拟合模型的评价指标均方根误差(root mean square error,RMSE)和标准化均方根误差(normalized RMSE,n-RMSE)的结果分别为0.09和4.13%,模型具有较好的稳定性。在试验氮素水平范围内,不同生育时期NNI随施氮量的增加而增加,变化范围为0.53~1.34,NNI可以准确地反映滴灌玉米氮素营养状况。在非限氮处理下,玉米植株氮素吸收与LAI成正比,LAI与PDM的异速生长参数接近理论值2/3。构建的基于LAI的临界氮曲线可以有效地识别玉米拔节期至吐丝期植株所需的氮状态,为宁夏滴灌玉米氮肥精确管理提供了一种新的评价方法。     

不同氮效率夏玉米临界氮浓度稀释模型与氮营养诊断

【目的】建立豫中地区玉米临界氮稀释曲线,比较不同氮素利用率玉米品种模型差异,探讨基于此的氮营养指数用于诊断、评价玉米氮素营养的可靠性,为实现玉米合理施用氮肥提供理论依据。【方法】以伟科702和中单909两个不同氮利用效率的品种为试验材料进行连续三年的田间定位试验,共设5个氮肥水平(0、120、180、240和360 kg/hm^2),分析不同施氮量对两个玉米品种拔节期、大喇叭口期、吐丝期、收获期干物质的影响,基于不同时期干物质和植株氮浓度建立两个品种临界氮稀释曲线,分析不同氮利用率品种玉米临界氮稀释曲线模型的差异和氮营养指数及其与相对地上部生物量和相对产量的关系。【结果】中单909的氮利用率显著高于伟科702。在各生育时期,两个玉米品种地上部生物量随施氮量变化表现为N0 –0.341,中单909 Nc=30.801DM^–0.370)具有很好的稳定性。相比中单909的模型参数,伟科702的参数a提高了15.70%,参数b降低了7.84%,且参数a变化值大于参数b。同一时期两个品种基于此模型的氮营养指数均随施氮量的增加而上升;施氮量低于180 kg/hm^2时,随着玉米生育时期的推进,氮营养指数随施氮量的增加呈先升高再降低的趋势,当施氮量超过240 kg/hm^2时,氮营养指数一直升高。氮营养指数与相对地上部生物量、相对产量相关性均达到显著水平。【结论】本文建立的豫中地区的两个品种玉米临界氮稀释曲线模型及氮营养指数,可以很好地诊断和评价玉米植株氮素营养状况。不同氮利用率品种间临界氮浓度稀释曲线模型参数存在差异,氮高效的品种具有较低的单位生物量氮浓度和较高的曲线斜率,其各时期临界氮浓度低于氮利用率低的品种。     

Determination of a critical dilution curve for nitrogen concentration in cotton

Several nitrogen (N)‐rate field experiments were carried out in cotton to define dilution curves for critical N concentrations in individual plants (i.e., the minimum N concentration required for maximum growth at any growth stage). Nitrogen application rate had a significant effect on aboveground dry matter, N accumulation, and N concentration. As expected, shoot N concentration in plants decreased during the growing period. These results support the concept of critical N concentration in shoot biomass of single plants as described by Lemaire et al. (2007) and reveal that a dilution curve for critical N concentrations in cotton plants can be described by a power equation. The pattern of critical–N concentration dilution curves was consistent across the two sites. Nitrogen concentration for a given biomass varied greatly with the supply of N. After initial flowering, the N‐nutrition index (NNI) for aboveground biomass of individual plants increased with increasing N rates. Relationships between plant total N uptake and accumulated dry matter in the aboveground biomass can be described by the allometric‐relation equations for each dose of N. Nitrogen‐dilution curves can be used as a tool for diagnosing the status of N in cotton from initial flowering to boll opening. The relationship can also be used in the parameterization and validation of growth models for predicting the N response and/or N requirement of cotton.     

关中平原不同降雨年型夏玉米临界氮稀释曲线模拟及验证

过量施氮和降雨变率大是陕西关中平原夏玉米种植中常见的2大问题,临界氮稀释曲线模型是诊断作物氮营养状况的有效手段。该研究选取关中平原主栽的6个夏玉米品种,设置了N0（0）、N1（86 kg/hm2）、N2（172 kg/hm2）和N3（258 kg/hm2）共4个施氮水平,在2013年（生育前期正常,后期大旱）和2014年（生育前期大旱,后期偏涝）这2种降雨年型下构建和验证了基于全生育期干物质的夏玉米临界氮稀释曲线。结果表明：2 a条件下临界氮浓度与地上生物量均符合幂指数关系,但模型参数存在部分差异,基于临界氮稀释曲线所建立的氮营养指数可用来诊断夏玉米氮盈亏状态,诊断结果表明氮营养指数均随着施氮量的增加而增加,且年型之间存在差异,最优施氮量介于86～172 kg/hm2之间。制定不同降雨年型下夏玉米临界氮稀释模型对于指导精确施氮及生育季氮诊断具有重要的意义。     

关中地区玉米临界氮浓度稀释曲线的建立和验证

基于临界氮浓度稀释曲线推导的氮素营养指数既可以诊断出氮素供应不足也可以诊断出氮肥供应过量。该文在整理分析关中平原8 a氮肥大田试验的基础上,分别构建了关中灌区夏玉米和渭北旱塬春玉米的地上部生物量的临界氮浓度稀释曲线模型。结果表明,关中玉米地上部临界氮浓度与生物量符合幂函数关系。利用独立试验资料对建立的临界氮稀释曲线模型进行检验,结果表明:该模型能准确诊断该区玉米植株的氮营养状况,施肥量和施肥时期对玉米植株的氮素营养状况影响较大,一般随着施氮量的增加氮素营养指数值会增大,只基施氮肥或前期施氮过多都会使玉米在生长过程中营养失衡。该研究建立的关中地区玉米的临界氮稀释模型为该区玉米氮素营养诊断和优化管理提供了较好的技术途径和理论参考。     

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.     

Grain yield and nitrogen use efficiency of various modern rice cultivars grown at different nitrogen levels

Field trials were conducted to study the responses of grain yield and nitrogen (N) use efficiency at five input rates (N₀, N_82.5, N₁₆₅, N_247.5, and N₃₃₀ kg ha^?1) in a set of nine of the most representative rice cultivars. Grain yields of rice across the nine cultivars were increased significantly by N level. All the cultivars contained a significant linear plus plateau or quadratic relationship between N levels and grain yields.The minimum yields (means of 2 years) at N₀, N_82.5, N₁₆₅, N_247.5, and N₃₃₀ level all occurred in No. 2 cultivar. Compared with the grain yield of No. 2 at different N levels, those of the maximum cultivars increased by 37.1 (No. 8), 39.1 (No. 7), 48.4 (No.3), 43.3 (No. 4), and 43.9% (No. 3), respectively. In 2011, the highest average apparent nitrogen recovery efficiency (ANRE) in grain of the 4 N levels occurred in No. 3 cultivar (45.9%), followed by No. 4, No. 6, and No. 1, and the highest average agronomic efficiency (AE) in grain of the 4 N levels occurred in No. 9 cultivar [29.0 kg (kg N)^?1], followed by No. 3, No. 1, and No. 4. For the second-season planting, the highest average ANRE occurred in No. 4 cultivar (28.4%), followed by No. 3, No. 5, and No. 6, and the highest average AE occurred in No. 5 cultivar [18.1 kg (kg N)^?1], followed by No. 4, No. 3, and No. 7. Overall, No. 3 and No. 4 cultivars were the ideal ones that not only increased the grain yield but also improved the N use efficiency.     

牛场肥水灌溉对冬小麦产量与氮利用效率及土壤硝态氮的影响

【目的】本研究利用田间小区试验,研究牛场肥水灌溉对冬小麦产量、 氮利用效率及土壤硝态氮的影响,以期为提高灌溉肥水中氮利用效率,降低养殖肥水灌溉的氮损失提供理论依据。【方法】通过田间小区定位试验,以华北平原典型冬小麦种植系统为研究对象,定量研究牛场肥水灌溉对冬小麦产量、 氮素积累、 氮效率及土壤硝态氮的影响。试验共设5个处理,分别为: 不施肥、 小麦各生育期进行清水灌溉(CK); 在冬小麦生育期内进行2次牛场肥水灌溉(越冬期和灌浆期,肥水灌溉带入氮量为160 kg/hm2),其他生育期清水灌溉(T1); 在冬小麦生育期内进行3次牛场肥水灌溉(越冬期、 拔节期、 灌浆期,肥水灌溉带入氮量为240 kg/hm2),其他生育期清水灌溉(T2); 在冬小麦生育期进行4次牛场肥水灌溉(越冬期、 拔节期、 抽穗期和灌浆期,肥水灌溉带入氮量为320 kg/hm2),不进行清水灌溉(T3); 农民习惯施肥,冬小麦播种时施复合肥(15-21-6)375 kg/hm2、 拔节期追肥尿素600 kg/hm2(氮投入量为332 kg/hm2),全生育期灌溉清水(CF)。每个处理重复3次,冬小麦全生育期灌水4次,灌水定额为830 m3/hm2,灌水量用超声波流量计计量。【结果】牛场肥水灌溉对冬小麦产量和氮的影响主要有以下几个方面: 1)连续三年冬小麦产量均随牛场肥水灌溉次数的增加表现为先增加后降低的趋势,肥水灌溉带入氮为240 kg/hm2(灌溉3次)时,冬小麦产量最高。2)牛场肥水灌溉显著增加冬小麦植株地上部氮积累量。2011年和2012年肥水灌溉的三个处理之间及与习惯施肥处理之间差异不显著,2013年T2和T3处理植株氮吸收量显著高于T1处理和习惯施肥处理。3)冬小麦肥水氮利用率和农学效率随肥水灌溉带入氮量的增加而降低。三年均以T1最高,分别为48.57%和37.15 kg/kg。4)每季冬小麦收获后,随着灌溉带入氮量的增加,0100 cm土层NO-3-N积累量增加。肥水灌溉带入氮为320 kg/hm2时,0100 cm剖面NO-3-N积累量显著高于肥水灌溉带入氮为160~240 kg/hm2处理。【结论】牛场肥水灌溉显著增加冬小麦产量,随肥水灌溉带入氮的增加冬小麦产量呈先增加后降低的趋势。冬小麦肥水氮表观利用率和农学效率均随肥水灌溉带入氮量的增加而降低,肥水灌溉带入氮为320 kg/hm2,80100 cm土层有大量NO-3-N累积,且有向下淋溶的趋势。本试验条件下,综合产量、 冬小麦植株氮积累量及氮效率等方面考虑,牛场肥水灌溉冬小麦适宜氮带入量为160~240 kg/hm2。     

滴灌条件下冬小麦施氮增产的光合生理响应

小麦籽粒产量与抽穗期之后的旗叶光合能力密切相关。为明确冬小麦施氮增产的光合生理响应,该文以充分滴灌不同N追肥量处理的冬小麦田为研究对象,抽穗期后进行3次旗叶光合-光响应曲线测定,量化并比较了旗叶光合能力(Amax)和表观光量子羧化效率(α)等参数及产量(Y)和水分利用效率(WUEa),并确定了旗叶比叶重(SLA)、N含量(N-mass和N-area)和13C同位素甄别率(Δ)对光合参数及产量的影响。分析表明:充分滴灌条件下,增施N肥能延长旗叶光合功能持续期,提高Amax和α,以高N处理(N3,207kg/hm2)处理最为显著(P=0.046),在生育中后期仍能保持较高的Amax,这也是N3处理Y较高的主要原因。而N肥对农田耗水影响不显著,高N处理的WUEa也较高。Amax的提高和维持与旗叶SLA、N-mass、N-area和Δ的变化有关,N肥处理也显著影响了Amax与SLA、N-mass、N-area和Δ之间的线性相关关系。该结果从光合生理角度阐明了冬小麦施氮增产的生理因素,可为该地区冬小麦滴灌施肥管理提供参考。     

不同灌溉措施对黄淮海地区冬小麦水氮利用及产量和品质的影响

通过设置不同灌溉处理来研究灌溉次数和时期对黄淮海地区冬小麦产量、籽粒品质和水氮利用的影响。结果表明:浇足底墒基础上拔节期灌一水不仅可获得较高的产量并提高水氮利用效率,减低硝态氮淋失风险,而且可获得较好的物理品质(硬度指数、容重)和蛋白质品质(粗蛋白、湿面筋和沉淀值)及最优的粉质仪质量指数、拉伸仪参数和降落数值。在此基础上增加冻水、开花水、灌浆水等处理的产量增加不显著,各项品质指标没有明显改善,水分利用效率降低,而且显著增加硝态氮淋失风险;因而黄淮海地区最优的节水灌溉模式是浇足底墒基础上拔节至挑旗期灌溉一水。     

平水年和欠水年渭北旱地冬小麦临界氮浓度稀释曲线构建

降雨波动大和过量施氮是限制渭北旱地冬小麦生产中氮肥高效利用和高产稳产的主要因子。该研究旨在构建2种降雨年型下冬小麦临界氮浓度稀释曲线,分析氮营养指数诊断冬小麦氮素营养状况的可行性,为考虑降雨条件下旱地冬小麦精准施氮提供理论依据。于2017—2021年在陕西合阳县开展4 a定位施氮试验,以晋麦47为试验材料,设置0、60、120、180、240 kg/hm² 5个施氮水平,其中2017—2018年和2020—2021年为平水年,2018—2019和2019—2020年为欠水年。研究2种降雨年型下施氮量对冬小麦氮素利用、产量及产量构成因素的影响,基于2种降雨年型下地上部生物量与植株氮浓度之间的关系,构建临界氮浓度稀释曲线模型和氮营养指数(nitrogen nutrition index,NNI)优化施肥方案。结果表明:1)施氮量、降雨年型及其二者互作效应对穗数、千粒质量、产量影响显著或极显著。2)2种降雨年型下冬小麦临界植株氮浓度和地上部生物量均符合幂函数关系,但模型参数之间存在差异(模型参数a在平水年和欠水年分别为3.33、2.79 g/kg,参数b在平水年和欠水年...     

密度、氮肥互作对小麦产量及氮素利用效率的影响

为了探明小麦产量和氮素利用效率同步提高的最佳施氮量和种植密度,制定合理的栽培措施,实现高产高效提供理论依据,以大穗型品种泰农18（T18）和中穗型品种山农15（S15）为试材,在大田条件下设置4个播种密度（60、75、90和105 kg/hm2）和3个施氮水平（0、180和240 kg/hm2）,研究了氮密互作对小麦子粒产量和氮素利用效率的影响。结果表明,播种密度和施氮量均显著影响冬小麦产量及构成因素,且两者间存在明显的互作效应;两因素中密度是导致产量变化的主导因素。子粒产量提高引起氮肥农学利用效率和氮肥吸收利用率的协同提高。综合考虑产量和氮素利用效率等因素,在本试验条件下,泰农18的适宜播量为102 kg/hm2,适宜的施氮量为180 kg/hm2;而山农15的适宜播量为83 kg/hm2,适宜的施氮量为180 kg/hm2。说明在冬小麦高产栽培过程中,可以通过调节施氮量和播种密度,充分利用氮密互作效应,在提高氮素利用率的同时,获得较高的子粒产量。     

Relationship between rainfall-adjusted nitrogen nutrition index and yield of wheat in Western Australia

Abstract

Insufficient nitrogen applications may contribute to yield gaps in low rainfall environments of Western Australia (WA). This study tested a nitrogen nutrition index (NNI) for wheat tailored for low rainfall regions, which is based on rainfall-scaled dilution curves. We analyzed yield, shoot biomass, and nitrogen concentration from 32 field trials in WA. An empirical rainfall threshold of 400?mm (summer?+?growing season rainfall) returned two parallel dilution curves accounting for the reduction of critical N in drier and lower yielding conditions. Scatterplots of relative yield and rainfall-adjusted NNI returned a robust boundary function that may lead to greater adoption by growers. The NNI defined in this research study can be applied and further tested by growers in WA, but may also apply to other low rainfall environments, to close nitrogen related yield gaps.     

Relationships among important traits in the nitrogen economy of winter wheat

Identification and utilization of important attributes in the nitrogen economy of wheat (Triticum aestivum L.) should provide a basis for increasing grain protein percentage (GPP). The objectives of this study were to determine the magnitude of genetic variability of some factors important in the nitrogen economy of wheat, their relationship to one another, and their influence on grain yield (GY) and GPP. Twenty‐five hard red winter wheat genotypes representing a wide range of GY, GPP, and plant stature were grown in field trials over a 2‐year period. Significant differences were found for harvest index (HI) and nitrogen harvest index (NHI). Total nitrogen at anthesis (TNA), total nitrogen at maturity (TNM), and biological yield (BY) did not differ significantly. GPP was positively correlated with TNM and BY and negatively correlated with TNA, HI, and GY. GPP was not correlated with NHI, however, stepwise regression of GPP and grain protein yield revealed NHI as a common component, with a positive coefficient. In addition, NHI was positively correlated with GY. Selection of parents with complementary traits for nitrogen‐use efficiency may allow for simultaneous increases in GY and GPP.     

基于氮素营养指数的冬小麦籽粒蛋白质含量遥感反演

基于遥感实现小麦籽粒蛋白质含量提早估测对农业生产具有重要意义。为提高预测小麦籽粒蛋白质含量的准确度,该研究引入能更好反映作物氮素营养状况的农学参数－氮素营养指数,作为衔接遥感信息与产终籽粒蛋白质含量的桥梁。在田间试验的基础上,探讨氮素营养指数与其他农学参数在诊断籽粒蛋白质含量上的优劣,并基于“遥感参数－氮素营养指数－籽粒蛋白质含量”间关系,利用主成分回归算法构建估测籽粒蛋白质含量的遥感反演模型。结果表明,相比于其他参数,冬小麦旗叶期氮素营养指数能更好的反映产终籽粒蛋白质含量;以氮素营养指数为中间变量,所建遥感反演模型能准确预测小麦籽粒蛋白质含量,模型的预测决定系数为0.48,预测标准误差为0.38%,相对误差为2.32%。     

Lowland Rice Genotypes Evaluation for Nitrogen Use Efficiency

Rice is important crop for world population, including Brazil. Nitrogen (N) is one of the most yield limiting nutrients in rice production under all agro-ecological conditions. A greenhouse experiment was conducted to evaluate N responses to 12 lowland rice genotypes. Soil used in the experiment was a Gley humic according to Brazilian soil classification system and Inceptisol according to USA soil taxonomy classification. The N rates used were 0 mg kg^?1 (low) and 300 mg kg^?1 (high) of soil. Plant height, straw yield, grain yield, panicle density, 1000 grain weight, and root dry weight were significantly increased with the addition of N fertilization. These growth, yield, and yield components were also significantly influenced by genotype treatment. Grain yield had significant linear or quadratic association with shoot dry weight, panicle number and 1000 grain weight Based on grain efficiency index genotypes were classified as efficient, moderately efficient and inefficient in N use. The N efficient genotypes were ‘BRS Tropical’, ‘BRS Jaçanã’, ‘BRA 02654’, ‘BRA 051077’, ‘BRA 051083’, ‘BRA 051108’, ‘BRA 051130’ and ‘BRA 051250’. Remaining genotypes fall into moderately efficient group. None of the genotypes were grouped as inefficient in N use efficiency.     

Effect of biochar-amended urea on nitrogen economy of soil for improving the growth and yield of wheat (Triticum Aestivum L.) under field condition

A field experiment was conducted to evaluate effect of biochar-amended urea on nitrogen economy of soil for improving the growth and yield of wheat under field condition. Experiment plan was comprised of twelve treatments with four replications including treatments without application of urea and biochar (control) and urea only. Biochar was applied at 1–10% of the weight of urea fertilizer applied each treatment. Results showed that application of biochar at 10% with recommended dose of urea significantly improved plant height, spike length, number of tillers, number of spikelet per spike, 1000 grain weight, grain yields, biomass yield, harvesting index, nitrogen (N) concentration and uptake in grain and straw, and agronomic efficiency of nitrogen by 6.0%, 11.1%, 32.0%, 55.3%, 5.4%, 38.0%, 19.0%, 9.0%, 19.0%, 26.0%, 65.0%, 50.0%, and 63.0%, respectively, as compared to treatment comprised of recommended rate of nitrogen without biochar.     

施氮模式对冬小麦/夏玉米产量及氮素利用的影响

采用大田试验,在小麦季N 250kg /hm2和玉米季N 200kg /hm2氮肥供应条件下,连续2年度（2007～2009）观测了不同施氮模式对冬小麦/夏玉米产量及氮素利用的影响。结果表明,与对照相比,常规施肥、有机无机复合肥、控释复合肥、控失复合肥以及改变氮肥基追配比处理均显著提高冬小麦/夏玉米子粒产量和干物质积累量,小麦季各处理产量大小依次为:控释复合肥控失复合肥有机无机复合肥改变氮肥基追配比常规施肥,提高幅度在107.5%～147.4%;玉米季各处理产量大小依次为:控释复合肥控失复合肥有机无机复合肥常规施肥改变氮肥基追配比,提高幅度在28.5%～56.1%。与常规施肥处理比较,控释复合肥、控失复合肥和有机无机复合肥处理冬小麦氮肥偏生产力和氮肥农学效率提高2.2～5.1 kg/kg,夏玉米提高3.6～7.6 kg/kg;但改变基追配比处理在小麦季高于常规处理,在玉米季则低于当地常规施肥处理。从产量和氮肥利用率方面综合分析,有机无机复合肥、控释复合肥、控失复合肥均可作为适宜研究区域推广的肥料品种,而改变基追配比处理相对较适宜冬小麦季。     

不同生态稻作区氮肥增产效应及其利用率

在4个典型生态粳稻区,以广适性的5个品种为材料,研究氮肥对不同稻区产量影响,并分析氮肥利用率及其不同稻区施氮效果的差异。结果表明:氮肥施用显著提高不同稻区产量,施氮增产率及其贡献率大小顺序为温暖粳稻区寒冷粳稻区籼粳交错区冷凉粳稻区,寒冷粳稻区产量提高主要是有效穗数和千粒重的增加,而其它3个稻区产量的提高主要是有效穗数和每穗粒数的增加所致。生产等量的稻谷氮肥需要量的大小顺序为寒冷粳稻区冷凉粳稻区籼粳交错区温暖粳稻区。不同稻区对氮肥的利用效率存在差异,氮肥农学利用率大小顺序为温暖粳稻区籼粳交错区冷凉粳稻区寒冷粳稻区,氮肥吸收利用率大小顺序为籼粳交错区温暖粳稻区冷凉粳稻区寒冷粳稻区,4个稻作区的土壤氮素贡献率在61.10%~66.09%之间,说明各稻作区吸收的氮肥主要来自土壤,通过培肥地力,维持较高的地力水平对稻谷的超高产、高效具有重要意义。