公顷产10000kg小麦氮素和干物质积累与分配特性

以泰山23和济麦22为试验品种,通过连续2年的田间试验,对单产高达10 000 kg hm^-2的小麦进行了施氮量和氮素吸收转运和分配特性的研究。在2006-2007年生长季,随着施氮量的增加,小麦籽粒产量先增加后降低,施纯氮240 kg hm^-2 (N240)和270 kg hm^-2(N270)处理的产量分别达9 954.73 kg hm^-2和10 647.02 kg hm^-2,比不施氮肥处理(N0)分别增加11.20%和18.93%。与N0处理相比,施氮处理显著增加了小麦植株氮素积累量、籽粒氮素积累量和开花后营养器官氮素向籽粒的转运量;随着施氮量的增加,成熟期小麦植株氮素积累量呈先增后降趋势,以N270处理最高;开花后营养器官氮素向小麦籽粒转运量和转运率先升后降,转运量以N270处理最大,为213.78 kg hm^-2;而转运率以N240处理最高,为67.98%。随施氮量的增加,小麦成熟期各器官干物质积累量、花后营养器官干物质再分配量和再分配率先增后降,均以N270处理最高;开花后干物质积累对籽粒的贡献率亦呈先增后降的趋势,以N240处理最高。2005-2006年的试验结果呈相同变化趋势。在本试验条件下,小麦产量水平达10 000 kg hm^-2时的适宜施氮量为240~270 kg hm^-2,可供生产中参考。     

公顷产10000kg小麦氮素和干物质积累与分配特性

以泰山23和济麦22为试验品种,通过连续2年的田间试验,对单产高达10 000 kg hm^-2的小麦进行了施氮量和氮素吸收转运和分配特性的研究。在2006—2007年生长季,随着施氮量的增加,小麦籽粒产量先增加后降低,施纯氮240 kg hm^-2 (N240)和270 kg hm^-2(N270)处理的产量分别达9 954.73 kg hm^-2和10 647.02 kg hm^-2,比不施氮肥处理(N0)分别增加11.20%和18.93%。与N0处理相比,施氮处理显著增加了小麦植株氮素积累量、籽粒氮素积累量和开花后营养器官氮素向籽粒的转运量;随着施氮量的增加,成熟期小麦植株氮素积累量呈先增后降趋势,以N270处理最高;开花后营养器官氮素向小麦籽粒转运量和转运率先升后降,转运量以N270处理最大,为213.78 kg hm^-2;而转运率以N240处理最高,为67.98%。随施氮量的增加,小麦成熟期各器官干物质积累量、花后营养器官干物质再分配量和再分配率先增后降,均以N270处理最高;开花后干物质积累对籽粒的贡献率亦呈先增后降的趋势,以N240处理最高。2005—2006年的试验结果呈相同变化趋势。在本试验条件下,小麦产量水平达10 000 kg hm^-2时的适宜施氮量为240~270 kg hm^-2,可供生产中参考。     

麦季氮肥运筹对冬小麦–夏玉米种植体系物质生产及氮肥利用的影响

2009-2011年在山东临沂冬小麦-夏玉米生产田,探讨了麦季施氮水平和施氮时期对两季作物干物质积累与分配、籽粒产量、氮肥农学利用率和氮肥偏生产力的影响。施氮量设4个处理,分别是0 (N0)、168.75 (N1)、225 (N2)和281.25 kg hm^-2 (N3);氮肥追施时期设2个处理,分别为拔节期(S1)和拔节期+开花期(S2)。在S1条件下,冬小麦和夏玉米的籽粒干物质积累量及夏玉米和周年生物产量均表现为N3>N2>N1,冬小麦和夏玉米的籽粒产量N2和N3处理间无显著差异;氮肥农学利用率和氮肥偏生产力在麦季随施氮量增加显著降低,而在玉米季则逐渐升高,但玉米季氮肥偏生产力N3与N2处理间无显著差异。S2条件下麦季施氮量由N2处理增加25% (N3),冬小麦和夏玉米籽粒干物质积累量、生物产量和籽粒产量无显著变化,氮肥农学利用率和氮肥偏生产力在麦季显著降低、在玉米季无显著变化。与S1相比,S2有利于提高N1和N2条件下冬小麦籽粒与营养器官的干物质积累量、生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力,但对N3条件下的这些指标无显著影响;而在玉米季,3个施氮量水平下夏玉米的各项指标均显著升高。综合周年生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力结果,麦季总施氮量225 kg hm^-2及拔节期+开花期追氮是本试验条件和种植模式下的最佳麦季氮肥运筹模式。     

氮肥用量及钾肥施用对稻麦周年产量及效益的影响

为探明优化施氮量与高施氮量下不同钾肥施用处理对稻麦周年产量及效益的影响。本试验于2010年5月–2011年7月在江苏省如皋市农业科学研究所试验基地的田间稻麦轮作条件下,对常规粳稻品种镇稻11和春性中筋品种扬麦16设置了两个氮肥用量下不同钾肥用量及施用方法处理,测定稻麦周年的产量和组成因子,成熟期不同器官的氮、钾浓度和累积量,氮、钾利用效率及经济效益。试验结果表明,钾肥的施用显著提高了周年稻麦的产量,同时提高了稻麦的有效穗数、穗粒数和结实率,钾肥的利用效率和经济效益。稻麦周年钾肥(K₂O)的偏生产力(PFP)、农学效率(AE)、回收利用率(RE)和经济效益均以周年钾肥(K2O)土壤施用150 kg hm^-2 + 叶面喷施16.2 kg hm^-2 (K_S150 + K_F16.2)处理最高。氮肥用量的结果表明,相对于优化施氮量,高施氮量有利于提高水稻的氮素营养而增产,但对稻麦周年产量的影响不显著,且优化施氮量的氮肥利用效率及经济效益均高于高施氮量。因此,综合考虑土壤环境因素、经济效益和肥料资源管理,本地区最佳氮肥(N)用量为水稻200 kg hm^-2,小麦180 kg hm^-2;最佳钾肥(K₂O)用量及方法为水稻土壤施用90 kg hm^-2 + 叶面喷施9.7 kg hm^-2 (K_S90 + K_F9.7),小麦土壤施用60 kg hm^-2 + 叶面喷施6.5 kg hm^-2 (K_S60 + K_F6.5)。     

Winter Wheat Cultivar Responses to Fungicide Application are Affected by Nitrogen Fertilization Rate

Foliar fungicides are important management inputs for winter wheat (Triticum aestivum L.) in high-yielding areas of Europe, but their effectiveness may interact with cultivar selection and nitrogen (N) fertilization. No information is available on the potential use of fungicides in reducing yield losses from foliar diseases in Croatia, where wheat crop is extensively grown under low N inputs. Field experiments were conducted during 2000–02 to evaluate the agronomic responses of six winter wheat cultivars to fungicide application (tebuconazol around heading) compared with untreated plots at low (67 kg N ha⁻¹) and high (194 kg N ha⁻¹) N fertilization rates. Grain yields tended to increase in all years following fungicide treatment at high N rate by an average of 10.1 % (773 kg ha⁻¹), but improved significantly in one year only at low N rate. When these occurred, yield increases were associated with larger grain weight per ear primarily due to heavier 1000-kernel weight. Cultivars differed in their responses to fungicide application across growing seasons and N fertilization rates. Under low disease pressure in 2000 and 2001, improved yields with fungicide use occurred for few susceptible cultivars only, whereas all cultivars significantly increased yields under higher disease severity in 2002 by an average of 383 kg ha⁻¹ (5.0 %) at low N rate and 1443 kg ha⁻¹ (19.0 %) at high N rate. Following fungicide application at high N rate, some susceptible cultivars outyielded resistant cultivars, whereas opposite responses occurred in untreated plots. High N fertilization rate consistently produced larger grain yields except under high disease severity and no fungicide sprayed in 2002, when it had no benefits at all over low N rate. Fungicide application showed limited importance for wheat performance at low N rate; however, cultivars significantly differed in yield responses as well as in rankings after fungicide use at high N fertilization rate.     

Exogenous Glycinebetaine Enhances Grain Yield of Maize, Sorghum and Wheat Grown Under Two Supplementary Watering Regimes

Drought occurring at critical growth and developmental stages in cereals affects productivity by reducing biomass accumulation, grain set, and grain yield and quality. Maize (cv. SR-73), sorghum (cv. Trump), and wheat (cv. Spear) were established in drought-prone field conditions in Perth, Western Australia, in l994. The plants were then subjected to optimal and suboptimal supplementary watering regimes at growth stages that were sensitive to water availability. Glycinebetaine in aqueous solution was applied to leaves at three rates (2, 4 and 6 kg ha^?1 and a control) to establish whether its application could ameliorate the effects of drought on the yield of the crops. Above-ground biomass production was measured at the beginning and at termination of the watering regimes. Leaf tissue glycinebetaine concentrations were determined 1 and 3 weeks after application. At physiological maturity, grains from the crops were harvested and grain yield, number of grains m^?2 and single grain weight were recorded. Drought significantly reduced above-ground biomass production in maize (P = 0.047), but not in sorghum and wheat. Grain yield of maize, number of grains m^?2 of maize and sorghum, and single grain weight of sorghum were significantly depressed by drought. Foliar application of aqueous glycinebetaine marginally enhanced biomass production in the three crops and significantly increased grain yield of maize (P = 0.001) and sorghum (P = 0.003). It also resulted in more grains m^?2 of maize, sorghum and wheat (P = 0.001, 0.001 and 0.003, respectively), with interactions between water and glycinebetaine treatments for sorghum and wheat (P = 0.001 and 0.001. respectively). Residual tissue glycinebetaine levels remained high 3 weeks after application to the crops. The positive effects of glycinebetaine treatment appear to be linked to its physiological role as a plant osmoticum that improves drought tolerance. The results of these studies suggest that foliar application of glycinebetaine may be used to improve drought tolerance and economic yield of maize and sorghum, but not of wheat. Increased grain yield was associated with more grains m^?2 rather than greater single grain weight.     

Application of pig slurry—First year and residual effects on yield and N balance

Crops generally utilize nitrogen (N) from slurries less efficiently than from mineral fertilizers. In order to compare the effects of slurry and mineral N application on yield and residual fertilization effects, a long-term field trial was established in autumn 1994, where pig slurry was applied to oilseed rape (OSR), winter wheat and winter barley at the same application dates as mineral N fertilizer. N amounts ranged from 0 to 240 kg total N ha⁻¹. The same treatment regimes were applied to the same plots in each year. Starting in 2010 (2011), wheat (barley) received no N fertilization in order to allow for testing residual fertilizer effects. Every year seed yield and N offtake by the seeds were determined.Accounting only for ammonia N of pig slurry, similar seed yields in OSR and slightly higher grain yields in wheat and barley compared to mineral N fertilizer were achieved. This indicates that mineralization of organically bounded slurry N compensated gaseous ammonia losses. In plots without N fertilization, OSR showed no yield trends during the experimental period, whereas wheat (barley) yield started to decrease after 10 (13) years without N fertilization. In the highly fertilized treatments, no significant trend in seed yield or N amount required for maximum yield could be detected. In the subsequent unfertilized wheat crop, accumulated slurry effects increased grain yield more than those of mineral N fertilizer. Barley grown in the second year without N supply remained unaffected by the previous slurry N application.     

施氮量对稻麦干物质转运与氮肥利用的影响

为探讨太湖地区稻麦轮作农田适宜施氮量及氮素对干物质转运与氮肥利用的影响,于2007—2009年间在中国科学院常熟农业生态实验站建立田间定位试验。设置4个氮肥处理水平,分别用N0、N1、N2和N3表示。水稻各处理的施氮量分别为0、125、225和325kghm-2;小麦相应处理施氮量分别为0、94、169和244kghm-2(为稻季相应处理施氮量的75%)。结果表明,水稻施氮量超过225kghm-2,小麦施氮量超过169kghm-2后,产量增加不显著。水稻、小麦开花期干物质积累量均随施氮量的增加而增加,但花前营养器官干物质转运对籽粒贡献率均随氮肥用量增加而降低;氮肥农学效率与氮肥生理效率均随氮肥用量增加而降低,且N2与N3处理之间差异不显著;边际产量均随施氮量增加而下降,N3处理边际效益水稻平均低于3.1kgkg-1,小麦平均低于2.4kgkg-1。综上所述,无论水稻还是小麦,N2处理既能保证较高物质转运率,又能保证较高的氮肥利用效率与经济效益。     

施氮量对强筋小麦品种济麦20氮硫积累与再分配及籽粒品质的影响

为了探讨施氮量对小麦籽粒加工品质调控的生理基础,选用强筋品种济麦20,在山东省龙口市前诸留村和中村(在中村进行了连续两年定位试验),研究了田间高产条件下,小麦氮与硫积累和再分配与籽粒品质的关系及施氮量对其调控的效应。结果表明,随施氮量由0增加至195~204 kg hm^-2,开花期营养器官中氮和硫的积累量及开花后吸收分配至籽粒的氮量和硫量增加,开花后各营养器官中的氮向籽粒的再分配量及叶片和穗轴+颖壳中的硫向籽粒的再分配量增加,籽粒中氮和硫含量提高,氮、硫含量比（N/S比）由16.38~16.98降至14.22~14.48,谷蛋白含量比例提高,籽粒品质改善;施氮量为276~285 kg hm^-2时,植株氮积累量无显著变化,茎秆+叶鞘中氮转移量减少,残留量增多,抑制了硫向籽粒的转移,导致籽粒硫积累量和含量降低,N/S比升高至15.20~15.27,谷蛋白含量占总蛋白质含量的比例减少,籽粒品质下降。说明施氮量影响了植株氮、硫积累量及向籽粒再分配的数量,调节了籽粒氮和硫含量及N/S比,导致籽粒蛋白质组分比例的差异,进而影响了籽粒的加工品质。使品质改善的适宜籽粒N/S比为14.22~15.27。兼顾高产和优质的适宜施氮量为195~204 kg hm^-2。     

Strategies to Improve the Use Efficiency of Mineral Fertilizer Nitrogen Applied to Winter Wheat

Recovery of fertilizer nitrogen (N) applied to winter wheat crops at tillering in spring is lower than that of N applied at later growth stages because of higher losses and immobilization of N. Two strategies to reduce early N losses and N immobilization and to increase N availability for winter wheat, which should result in an improved N use efficiency (= higher N uptake and/or increased yield per unit fertilizer N), were evaluated. First, 16 winter wheat trials (eight sites in each of 1996 and 1997) were conducted to investigate the effects of reduced and increased N application rates at tillering and stem elongation, respectively, on yield and N uptake of grain. In treatment 90‐70‐60 (90 kg N ha^?1 at tillering, 70 kg N ha^?1 at stem elongation and 60 kg N ha^?1 at ear emergence), the average values for grain yield and grain N removal were up to 3.1 and 5.0 % higher than in treatment 120‐40‐60, reflecting conventional fertilizer practice. Higher grain N removal for the treatment with reduced N rates at tillering, 90‐70‐60, was attributed to lower N immobilization (and N losses), which increased fertilizer N availability. Secondly, as microorganisms prefer NH₄⁺ to NO₃^? for N immobilization, higher net N immobilization would be expected after application of the ammonium‐N form. In a pot experiment, net N immobilization was higher and dry matter yields and crop N contents at harvest were lower with ammonium (ammonium sulphate + nitrification inhibitor Dicyandiamide) than with nitrate (calcium nitrate) nutrition. Five field trials were then conducted to compare calcium nitrate (CN) and calcium ammonium nitrate (CAN) nutrition at tillering, followed by two CAN applications for both treatments. At harvest, crop N and grain yield were higher in the CN than in the CAN treatment at each N supply level. In conclusion, fertilizer N use efficiency in winter wheat can be improved if N availability to the crops is increased as a result of reduced N immobilization (and N losses) early in the growth period. N application systems could be modified towards strategies with lower N applications at tillering compensated by higher N dressing applications later. An additional advantage is expected to result from use of nitrate‐N fertilizers at tillering.     

Analysis of Wheat Cultivar Differences in Grain Yield, Grain Nitrogen Yield and Nitrogen Utilization Efficiency.

More detailed information on the causes of yield variability among wheat cultivars is needed to further increase wheat yield. Field studies were conducted in Northern Greece over the two cropping seasons of 1985—1986 and 1986—1987 to assess the effects of nitrogen fertilizer and application timing of the various component traits that determine grain yield, grain nitrogen yield and nitrogen utilization efficiency of two bread ( Triticum aestivum L.) and two durum ( Triticum durum Desf.) wheat cultivars, using yield and yield component analysis. Nitrogen at a rate of 150 kg ha^-1 was applied before planting or 100 N kg ha^-1 before planting and then 50 N kg ha^-1 top dressed at early boot stage. Nitrogen and cultivars affected all traits examined, while split nitrogen application affected only some of the traits. Grain yields in the most cases were correlated with number of grains per unit area and grain weight and grain nitrogen yields in all cases with grain number per unit area. The contribution of the number of grains per spike to total variation in grain yield among cultivars was almost consistent (37 to 55 %), while the contribution of grain weight was more significant (up to 55 %) in high yields (>6.500kg ha^-1) and number of spikes per unit area (>500). The number of grains per spike contributed from 60 to 83 % to the total variation in grain nitrogen per spike. Increased grain nitrogen concentration resulted in a reduction of its contribution in grain nitrogen yield variation. Nitrogen utilization efficiency was higher during grain filling than during vegetative biomass accumulation. The contribution of nitrogen harvest index to the variation of utilization efficiency for grain yield was higher in plants receiving nitrogen application.     

Dry matter,nitrogen and phosphorus accumulation,partitioning and remobilization as affected by N and P fertilization and source–sink relations

Durum wheat (Triticum turgidum subsp. durum L.) is being increasingly grown in many areas of the world, but there is a lack of information about the physiological processes limiting grain yield. In this study, different rates of N and P fertilization were applied and the source:sink ratio was manipulated to examine the factor(s) limiting grain filling under rainfed conditions. Plants exposed to four fertilization treatments (control, 80 kg N ha^?1 (N), 50 kg P ha^?1 (P) and 80 kg N ha^?1 and 50 kg P ha^?1 (N–P)) and were artificially modified to obtain a range of different source:sink ratios. The treatments were (I) control; (II) half of the spike was removed; (III) all the spike was removed. The cultivar Cosmodur was used, which is widely grown in Greece and other Mediterranean countries and is quite productive especially under rainfed conditions. The distribution of dry matter, N and P among grains, stems and leaves was analyzed at anthesis and harvesting. Dry matter accumulation and partitioning into different plant parts was different between the fertilization treatments and the control. At anthesis, leaf + culm dry matter was higher than the chaff dry matter. Total aboveground biomass increased after anthesis in both years and at all fertilization treatments. N fertilization affected N concentration at the whole plant level at anthesis and at maturity. There was an average increase of 20% in N concentration with N application at anthesis in both years relative to the control. N content was affected by the fertilization treatments and it was increased by 33% over the 2 years of the study compared with the control. In addition, P fertilization affected P concentration both at anthesis and maturity in every plant organ, and there was also a significant effect of the change of P concentration at the two different growth stages. P accumulation was also affected by the fertilization regime and by the spike halving treatment. Dry matter translocation was an average of 22% higher at the fertilized treatments compared with the control, which indicates that fertilization led plants to translocate higher amount of dry matter. N and P translocation were affected by the fertilization treatment and in some treatments by the sink reduction. The spike reduction treatment increased the pre-anthesis contribution to seed indicating that the N and P remobilization from vegetative tissues were very important for grain development. The present study indicates that N and P fertilization and sink size can affect dry matter, N, and P accumulation, partitioning, and retranslocation of durum wheat which can affect seed yield.     

Productivity and Sustainability of Cotton (Gossypium hirsutum L.)–Wheat (Triticum aestivum L.) Cropping System as Influenced by Prilled Urea, Farmyard Manure and Azotobacter

Field experiments were conducted at Indian Agricultural Research Institute, New Delhi, during 2001–2002 and 2002–2003, to study the effect of inorganic, organic and Azotobacter combined sources of N on cotton (Gossypium hirsutum L.) and their residual effect on succeeding wheat (Triticum aestivum L.) crop. The results indicated considerable increase in yield attributes and mean seed cotton yield (2.33 Mg ha^?1) with the combined application of 30 kg N and farmyard manure (FYM) at 12 Mg ha^?1 along with Azotobacter (M₄). The treatment in cotton that included FYM, especially when fertilizer N was also applied could either improve or maintain the soil fertility status in terms of available N, P and K. Distinct increase in yield attributes and grain yield of wheat was observed with the residual effect of integrated application of 30 kg N ha^?1 + FYM at 12 Mg ha^?1 + Azotobacter. Direct application of 120 kg N ha^?1 resulted 67.4 and 17.7 % increase in mean grain yield of wheat over no N and 60 kg N ha^?1, respectively. Integrated application of organic and inorganic fertilizer is therefore, recommended for higher productivity and sustainability of the cotton–wheat system.     

Effect of Different Crop Densities of Winter Wheat on Recovery of Nitrogen in Crop and Soil within the Growth Period

Previous experiments have shown that, at harvest of winter wheat, recovery of fertilizer N applied in early spring [tillering, Zadok’s growth stage (GS) 25] is lower than that of N applied later in the growth period. This can be explained by losses and immobilization of N, which might be higher between GS 25 and stem elongation (GS 31). It was hypothesized that a higher crop density (i.e. more plants per unit area) results in an increased uptake of fertilizer N applied at GS 25, so that less fertilizer N is subject to losses and immobilization. Different crop densities of winter wheat at GS 25 were established by sowing densities of 100 seeds m^–2 (S_low), 375 seeds m^–2 (S_cfp= common farming practice) and 650 seeds m^–2 (S_high) in autumn. The effect of sowing density on crop N uptake and apparent fertilizer N recovery (aFNrec = N in fertilized treatments ? N in unfertilized treatments) in crops and soil mineral N (N_min), as well as on lost and immobilized N (i.e. non‐recovered N = N rate ? aFNrec), was investigated for two periods after N application at GS 25 [i.e. from GS 25 to 15 days later (GS 25 + 15d), and from GS 25 + 15d to GS 31] and in a third period between GS 31 and harvest (i.e. after second and third N applications). Fertilizer N rates varied at GS 25 (0, 43 and 103 kg N ha^–1), GS 31 (0 and 30 kg N ha^–1) and ear emergence (0, 30 and 60 kg ha^–1). At GS 25 + 15d, non‐recovered N was highest (up to 33 kg N ha^–1 and up to 74 kg N ha^–1 at N rates of 43 and 103 kg N ha^–1, respectively) due to low crop N uptake after the first N dressing. Non‐recovered N was not affected by sowing density. Re‐mineralization during later growth stages indicated that non‐recovered N had been immobilized. N uptake rates from the second and third N applications were lowest for S_low, so non‐recovered N at harvest was highest for S_low. Although non‐recovered N was similar for S_cfp and S_high, the highest grain yields were found at S_cfp and N dressings of 43 + 30 + 60 kg N ha^–1. This combination of sowing density and N rates was the closest to common farming practice. Grain yields were lower for S_high than for S_cfp, presumably due to high competition between plants for nutrients and water. In conclusion, reducing or increasing sowing density compared to S_cfp did not reduce immobilization (and losses) of fertilizer N and did not result in increased fertilizer N use efficiency or grain yields.     

Effects of 15N Split-application on Soil and Fertiliser N Uptake of Barley, Oilseed Rape and Wheat in Different Cropping Systems

In intensive farming systems, farmers split up and apply the N fertilization to winter cereals and oilseed rape (OSR) at several dates to meet the need of the crop more precisely. Our objective was to determine how prior fertilizer N application as slurry and/or mineral N affects contributions of fertilizer‐ and soil‐derived N to N uptake of barley (1997), oilseed rape (OSR; 1998) and wheat (1999). In addition, residual fertilizer N effects were observed in the subsequent crop. Since autumn 1991, slurry (none, slurry in autumn, in spring, in autumn plus in spring) and mineral N fertilizer (0, 12 and 24 g N m⁻²) were applied annually. Each year, the treatments were located on the same plots. In 1997–1999, the splitting rates of the mineral N fertilization were labelled with ¹⁵N. Non‐fertilizer N uptake was estimated from the total N uptake and the fertilizer ¹⁵N uptake. All three crops utilized the splitting rates differently depending on the time of application. Uptake of N derived from the first N rate applied at the beginning of spring growth was poorer than that from the second splitting rate applied at stem elongation (cereals) or third splitting rate applied at ear emergence or bud formation (all three crops). In contrast, N applied later in the growing season was taken up more quickly, resulting in higher fertilizer N‐use efficiency. Mineral N fertilization of 24 g N m⁻² increased significantly non‐fertilizer N uptake of barley and OSR at most of the sampling dates during the growing season. In cereals, slurry changed the contribution of non‐fertilizer N to the grain N content only if applied in spring, while OSR utilized more autumn slurry N. In OSR and wheat, only small residual effects occurred. The results indicate that 7 years of varying N fertilization did not change the contribution of soil N to crop N uptake.     

Effect of Phosphorus and Nitrogen Fertilization on Sunflower (Helianthus annus L.) Nitrogen Uptake and Yield

Little is known about the effect of combined phosphorus and nitrogen (P‐N) fertilization on the N requirement of sunflower (Helianthus annus L.). This study was carried out to evaluate the effects of varying levels of P and N, as well as the interaction P × N, on the N uptake, yield and N apparent utilization efficiency under field conditions. Split‐plot design experiments were conducted in the mid‐western Pampas in Argentina. Four levels of N (0, 46, 92 and 138 kg N ha^?1) and three levels of P (0, 12 and 40 kg P ha^?1) were applied to two Typic Hapludolls over two growing seasons (1997–98 and 1998–99). N uptake and soil N‐NO₃ contents were determined at the V₇, R₅ and R₉ growth stages. The sunflower yield ranged from 2.5 to 5.0 Mg ha^?1. The total N requirement was around 45 kg N Mg^?1 grain, and this result suggests that it is not necessary to use different N requirements (parameter b) for fertilized crops when a yield response is expected. To achieve a 100 % yield maximum a N supply (soil plus fertilizer) of 181 kg N ha^?1 at P₄₀ was needed. However, at P₀, the highest yield was about 80 % of the maximum yield with a N supply (soil plus fertilizer) of 164 kg N ha^?1. P application increased the apparent use efficiency of the supplied N.     

Improving the productivity and profitability of irrigated rice production in Mauritania

Yield, input use, productivity and profitability of irrigated rice in Mauritania were analyzed during the 1997 wet season (July–December) in the Senegal river delta and middle valley, in collaboration with 42 large farmers and extension staff. Objectives were to determine agronomic constraints to rice cropping and to evaluate alternative crop management strategies aimed at overcoming these constraints. Grain yields ranged from 0.9 to 8.5 t ha⁻¹ and averaged 4.4 t ha⁻¹. Based on crop simulations, average yield potential in farmers' fields was estimated at 8.6 t ha⁻¹, indicating considerable scope for increased yields. Our survey identified the following main agronomic constraints: (i) mismatches between timing of nitrogen (N) fertilizer applications and critical N demanding growth stages of the rice plant; (ii) non-use of phosphorus (P) fertilizer on P deficient soils; (iii) largely neglected or inefficient weed management and (iv) late harvesting, often due to non-availability of combine harvesters. Based on these results we tested improved nutrient and weed management practices with farmers during the 1998 wet season. Improved nutrient management (i.e. T1: application of 20 kg P ha⁻¹ and 150 kg N ha⁻¹ in three splits at start tillering, panicle initiation and booting) increased yields by 0.9 t ha⁻¹. Improved weed management (i.e. T2: application of 6.0 L propanil ha⁻¹ and 2.0 L 2,4-d-amine ha⁻¹ at 2–3 leaf stage of weeds) also raised yields by 0.9 t ha⁻¹ as compared to farmers' practice (TP). The combined effect of T1 and T2 (i.e. T3) was additive: improving both nutrient and weed management raised yields by 1.8 t ha⁻¹ over average farmers’ yields of 3.9 t ha⁻¹, i.e. an increase of almost 50%. The improved crop management practices were highly profitable: compared to farmers’ practice, net benefits increased by 40% for T1 and T2 and by about 85% for T3, with minimal additive investments. Inputs used for T3 are relatively easily available in Mauritania. We concluded that increased farmer awareness of the profitability of improved nutrient and weed management may have a tremendous impact on the competitiveness of rice production in Mauritania     

秸秆还田与肥料运筹对冬小麦‘皖麦52’产量性状的调控效应

为了探讨玉米秸秆全量还田下氮磷钾肥运筹方式对小麦产量及构成因素的影响,以冬小麦‘皖麦52’为试验材料,在长期小麦-玉米连作试验地上对一年玉米秸秆全量还田下不同氮磷钾肥运筹方式进行了研究。结果表明,一年秸秆全量还田除对小麦千粒重影响显著外,对产量及其他构成影响均不显著,同时随施氮量的增加千粒重呈下降趋势,千粒重最高的处理是N24P12K12(41.5 g);不同氮磷钾肥运筹方式对小麦产量影响极显著,产量最高的施氮水平为N30P12K12(8572.5 kg/hm2),施磷水平为N36P18K12(9028.5 kg/hm2),施钾水平为N36P12K12(8500.5 kg/hm2),除钾肥运筹对穗数影响达显著水平外,对其他产量构成影响均达极显著水平;秸秆还田与施氮互作对小麦产量及其构成影响不显著,与施磷互作除对穗粒数影响达显著水平外,对产量及其他构成影响均达极显著水平;与施钾互作除对小麦产量及穗粒数影响达显著水平外,对其他构成影响均不显著。     

养分管理对直播稻产量和氮肥利用率的影响

为探明不同养分管理模式在实地农户种植条件下对直播水稻产量和氮肥利用率的影响。本试验于2011年6月至2013年11月在江苏省兴化市茅山镇基本农田保护区的田间稻麦轮作条件下,分别选取茅山东村、茅山西村和冯顾村各8个农户,开展3个不同养分管理模式试验,设置了不施肥对照(CK)、农民习惯施肥(FFP)和优化施肥(OPT1和OPT2)4个处理,主要研究了水稻产量及构成因子、氮累积分配和氮肥利用率等对不同养分管理模式的响应。结果表明：(1)施肥较不施肥显著提高水稻产量,优化施肥(226 kg N hm^-2)在较习惯施肥(333 kg N hm^-2)平均减氮32.1%的基础上显著提高水稻产量5.5%,增产原因是提高了穗粒数、结实率和千粒重;OPT2较OPT1平均增产3.1%,其原因是在孕穗期增施了钾肥(18 kg hm^-2 K₂O)。(2)优化施肥水稻植株各部位氮浓度、百千克籽粒需氮量和秸秆氮累积均显著低于习惯施肥,且降低营养器官的氮素分配比例。(3)优化施肥较习惯施肥显著提高水稻氮肥利用率,其氮肥偏生产力(PFP_N)、氮肥农学效率(AE_N)、氮肥回收效率(RE_N)和氮肥生理效率(PE_N)分别平均增加55.5%、79.1%、18.7%和48.7%。(4)水稻植株氮累积与产量呈显著正相关,且优化施肥单位氮累积的增产效果高于习惯施肥。因此,基于氮肥总量控制、分期调控和增施钾肥的养分优化管理措施可在实地农户直播稻种植上协同实现水稻高产和氮肥高效。     

氮素实时管理对冬小麦产量和氮素利用的影响

为实现氮素效率和小麦产量的协同提高,以山东省泰安市和兖州市为试验地点,连续2年在4个田块上进行了基于土壤硝态氮测试的氮素实时管理试验。与农民习惯施肥相比,优化施氮处理提高产量0.87%～10.44%,平均5.82%;而氮肥用量减少38.61%～53.29%,平均46.70%;氮素吸收效率、氮素表观利用率和氮素农学效率分别增加36.67%～85.69%、58.49%～267.69%和34.16%～410.58%;氮肥偏生产力升高74.23%～124.87%;产/投比提高78.50%～112.09%。说明应用土壤硝态氮测试进行小麦氮肥实时实地管理达到了减少氮肥用量,提高氮素利用效率,增加产量和经济效益的目的。