Ertragsbildung von getreidereichen Fruchtfolgen und Getreide-monokulturen in einem extensiven und intensiven Anbausystem

Yield formation in cereal-rich crop rotations and monocultures in an extensive and intensive crop-management system
In a long duration trial, conducted from 1979/80 to 1992 at TU-Munich's research station in Roggenstein, the performance of monocultures of winter wheat, winter barley and winter rye, as well as numerous cereal-crop rotations were compared in an extensive and intensive crop-management system. The results obtained can be summarized as follows.
Over the course of 13 years, the influence of the immediately preceding crop on the yield of the main crops was of much greater significance than the rotation as a whole. With winter wheat, no yield differences could be observed between monoculture and cereal crop rotation (if the rotation did not include oats). Oats, rape, field bean, pea, potato and maize as preceding crops, however, in crop management systems, led to, on average, an increase in yield of 13 dt/ha from the following wheat. Winter barley yields were not significantly different in monoculture, cereal crop rotations and crop rotations containing 66% cereals. Furthermore, winter rye yields were the same in monocultures and cereal crop rotations. With all cereals, intensification of fertilizing and chemical plant protection led to a considerable increase in yield, but did not diminish the effects of the preceding crop. Hence, even with the use of modern agronomical techniques it is impossible to compensate for yield losses due to crop rotation.     

N-Dynamik des Bodens, Ertragsbildung und Stickstoffentzug von Winterweizen bei unterschiedlicher Höhe und Verteilung der mineralischen N-Düngung

NO₃ dynamics in the soil, yield formation and N uptake of winter wheat as influenced by dosage and distribution effects of N-fertilizer application
In a 4 year series of field trials carried out with 9 regimes of nitrogen fertilizer application at two trial sites with rather shallow top soil layers but large deviations in soil characteristics, grain yield varied between 50 dt/ ha and 120 dt/ha with nitrogen doses from 0–170 kg N/ha. Soil nitrogen supply for wheat grain formation on unfertilized plots reached 80 kg N/ha/year within the narrow range of 75–95 kg N/ha in different years at both sites which amounts to 1.5 % and 0.5 % of the highly different N-content of the trial sites.
The most successful nitrogen application regimes are characterized by modest fertilizer doses in early spring and the delay of supplemental fertilizer doses until growth stage EC 32. They resulted into modest NO) soil content from EC 29 to EC 32 and/or a noticable decrease of soil NO₃ content during growth stage EC 30–32, which seems to be responsible for the development of only modest stand densities and reduced straw yield, while the delayed supplementation with nitrogen fertilizer overcompensated these effects mainly by increased grain numbers/ear and a remarkable improvement of harvest index.
The contribution of soil borne nitrogen to kernel yield formation started to decrease with even low dosages of supplemental nitrogen fertilization with the exception of the highest yielding season 1987/88. Top levels of grain yield have been regularly obtained with supplemental nitrogen fertilizer dosages about 40 kg N/ha below grain yield nitrogen extraction if they were added within favorable application regimes.     

The Influence of Crop Rotation with an Increasing Content of Cereals on Photosynthetic Potential of Winter Wheat

In years 1982–1985 flag leaf area, concentration of chlorophyll and macronutrients (N, P, K, Ca, Mg, Na) and also their correlations to grain yield in static field experiment were studied. The main experimental plots comprised crop rotations containing 50, 75, 100% cereals. Treatments with or without irrigation were subplots and nitrogen levels (0, 60, 120, 180 kg N/ha) were sub-sub-plots.
The cultivation of winter wheat in rotations containing more than 50% cereals affected the drop of winter wheat grain yield, which was especially high on the plots without nitrogen fertilization or with low N level. The dose of 120 kg N/ha gave the highest grain yield in each rotation and, at the same time, decreased to minimum the differences between them, although wheat grown in the full cereal rotation yielded much less. The response of wheat grain yield to previous crop was affected by photosynthetic potential of a plant, which was constituated by flag leaf area and concentration of chlorophyll. The deteriorating nutrient economy in wheat plants grown in rotations containing more than 50% cereals decreased the photosynthetic potential of wheat. In addition, in these rotations the importance of macronutrients concentration in the flag leaf at anthesis as a source of nutrients for the developing grain is visible.     

Ergebnisse zur Ertragsbildung bei ökologisch orientiertem Winterweizenanbau auf Lößschwarzerdeböden in trockenen Lagen

Results of yield formation at ecological oriented winter wheat cultivation on Calcic Chernozem soil in arid areas
The influence were examined in field experiments of wheater elements (air temperature, precipitation), nitrogen fertilization, sowing rate and irrigation on the yield and yield formation of winter wheat stands. The average level of yields amounts to 81.3 dt/ha (76…93.8 dt/ha). Limiting factor for yields is the availability of water in the soil. In humide seasons 9…12 % higher yields were obtained then in dry seasons. Without nitrogen fertilization yields of winter wheat are lower by 18 % than with nitrogen fertilization. At very high level of N fertilization only vegetative biomass increases, and the water use efficiency decreases.
Increase in plants/m² caused a rise of vegetative biomass and of ears/m², kernels per ear strongly decreased in the same time. At winter wheat cultivation in low input farming systems without nitrogen fertilization high yields will be obtained with 320…370 plants/m² and 15,000 kernels/m². Nitrogen uptake from the soil amounts to 180 kgN/ha. Because of great amounts of inorganic in the soil (70…200 kgN/ha) sufficient nitrogen is available until heading of the wheat plants. The nitrogen supply of wheat plants in later stages of development is influenced by wheater conditions.     

Die Ertragsentwicklung von Wintergetreide und Zuckerrüben bei dauerhafter Senkung des N-Düngungsniveaus

Effects of Long-term Fertilizer N Reduction on Winter Grain and Sugar Beet Yields
The results of recent field experiments concerning the effect of long-term N-reduction on the yield and quality of sugar beet, winter wheat and winter barley on plots which had previously had received ample amounts of N are studied in this paper.
The yield and quality of crops harvested on plots where N-dressings had been reduced for 6–8 years were similar to those of crops grown on plots where N-application had been reduced for only 1 year. Grain yield of winter wheat and winter barley grown without any N-application decreased to about 60 % of amounts normally harvested under local conditions with recommended N dressings, whereas the white sugar yield still remained at 90 %. The yields decreased slightly with an increase in the duration of the experiments. Yields of both cereals and beets remained constant within each level of fertilization, even 6 years after inition of trials with 50, 75 and 125 % of locally recommended N dressings.
On plots that did not receive nitrogen fertilization, N-contents of grain were between 1.5 and 1.7 % for winter wheat and 1.0 and 1.6 % N for winter barley. These contents remained constant over a trial period of 6 years. The amount of annual export of 55–91 kg N/ha also remained constant. Limited N availability causes a decrease in grain protein content rather than in grain yield.
Compared to winter grain species, sugar beet (with 74–117 kg N/ha in the beet body) could realize the highest annual export of nitrogen from the plot. Differences in annual N export existing between the various locations of the plots cannot be explained by differences in soil quality. Continuous high yields that were found even without any N-dressings may be explained by asymbiotic N-fixation, deposition of atmospheric N and a progressive decrease in soil N with 17–56 kg N/ha removed from soil resources annually.     

Residual nitrogen effect of clover-ryegrass swards on yield and N uptake of a subsequent winter wheat crop as studied by use of N methodology and mathematical modelling

The residual effect of 2-year-old swards of clover-ryegrass mixture and ryegrass in monoculture on yield and N uptake in a subsequent winter wheat crop was investigated by use of the ¹⁵N dilution method and by mathematical modelling. The amount of N in the wheat crop, derived from clover-ryegrass residues was 25–43% greater than that derived from residues of ryegrass which had been growing in monoculture. Expressed in absolute values, the N uptake in the subsequent winter wheat crop was 23–28 kg N ha ⁻¹ greater after clover-ryegrass mixture than after ryegrass in monoculture. Up to about 54 kg N ha⁻¹ of the N mineralised from the clover-ryegrass crop was calculated to be leached, whereas only 11 kg N ha⁻¹ was leached following ryegrass in monoculture.     

Untersuchungen zur Optimierung der N-Aufnahme von Winterweizenbeständen durch ergänzende Düngungmaßnahmen

Investigations on supplemental N-fertilizer application for the optimum course of N-uptake into winter wheat stands
During a period of 5 years 14 N-fertilization field trials with winter wheat have been carried out in which N-uptake and biomass production in 6 growth stages were analysed. By comparison with non-optimal variants of N-supply a critical range for N-uptake has been recognized which centered around an optimum value of 86 kg biomass N/ha at growth stage EC32. In connection with intensified N-uptake during later growth stages, this has allowed full exploitation of the wheat yield potential without substantial decrease of the N-harvest index.
Field trials on two different soil types (Parabraunerde and humose Auenrendzina), different dates of sowing and long year stands in wheat monoculture as well as applications of N-fertilizers containing dicyandiamid for delay of nitrification showed differences in efficiency as related to the fertilizer dosages but no systematic deviation from the optimum course of N-uptake for full exploitation of yield potential.
Provided that excessive fertilizer dosages before EC32 had been avoided, it seems possible to adjust the reuptake of winter wheat stands close to its optimum within an error of not more than 30 kg fertilizer N/ha by growth stage oriented splittings of fertilizer application and adequate account of soil-N supply and weather conditions during early growth stages.
Full exploitation of the wheat yield potential has been possible in all trials without significant losses in N-use efficiency if optimal splittings and dosages of supplemental N-fertilizers were provided.     

灌水运筹对冬小麦粒重和产量的影响

以农大 32 91为供试材料 ,研究了 2种灌水运筹方式对冬小麦产量形成的影响 ,并对密度、氮肥用量对灌水运筹效果的影响进行了分析。结果表明 :在造好底墒水的前提下 ,冬小麦春季灌 4次水 (简称 4水 )与春季灌 2次水 (简称 2水 )相比 ,千粒重增加 1 78g ,产量增加 665 1kg/hm2 ,但全生育期多耗水 73 65mm ,并且水分利用效率下降 7 63% ;经分析 ,差异显著。 4水比 2水多消耗的水分主要是土壤水并且集中在生育后期 (抽穗 -成熟 )。密度与氮肥的影响表现出有规律的变化 :节省氮肥用量和降低植株密度均有利于千粒重的提高 ,但产量有所降低     

Einfluß der N-Düngung auf Ertragsentwicklung landwirtschaftlicher Kulturen und Veränderung des mineralischen N-Gehaltes im Boden bei achtjährigen Dauerversuchen

Influence of long-time Nitrogen-fertilizing on yield response of agricultural crops and mineralized Nitrogen in soil
In the years 1979–1986 a fertilizer trial with increasing Nitrogen amount was performed in order to prove the N_min-method according to S charpf and W ehrmann . The N_min-method regards the mineralized N in soil (N_min) for optimizing the N-fertilizer amount at the begin of vegetation, could be confirmed. The optimal N-rate (including N_min) was for winter wheat and winter barley 120 kg/ha, winter rye 100 kg/ha and sugar beet 200 kg/ha. For cereals additional N-rates were given at the end of tillering 20 kg/ha N and at ear emergency 60 kg/ha N. For the optimal N-fertilizing system we found a positive N-balance (input-output) in a range of 10–25 kg/ha. The influence of N-fertilizing on the mineralized N-amount in soil was very small comparing to influence of weather, soil type or crops. Only at one location a little increase of N_min (10–15 kg/ha) could be observed after a positive N-balance (50 kg/ha).     

Effects of crop residue management on winter durum wheat productivity in a long term experiment in Southern Italy

A long-term experiment comparing different crop residue (CR) managements was established in 1977 in Foggia (Apulia region, southern Italy). The objective of this study was to investigate the long-term effects of different types of crop residue management on main yield response parameters in a continuous cropping system of winter durum wheat. In order to correctly interpret the results, models accounting for spatial error autocorrelation were used and compared with ordinary least square models.Eight crop residue management treatments, based on burning of wheat straw and stubble or their incorporation with or without N fertilization and irrigation, were compared. The experimental design was a complete randomized block with five replicates.Results indicated that the dynamics of yield, grain protein content and hectolitric weight of winter durum wheat did not show any decline as usually expected when a monoculture is carried out for a long time. In addition, the temporal variability of productivity was more affected by meteorological factors, such as air temperature and rainfall, than CR management treatments. Higher wheat grain yields and hectolitric weights quite frequently occurred after burning of wheat straw compared with straw incorporation without nitrogen fertilization and autumn irrigation and this was attributed to temporary mineral N immobilization in the soil. The rate of 50 kg ha⁻¹ of N seemed to counterbalance this negative effect when good condition of soil moisture occurred in the autumn period, so yielding the same productive level of straw burning treatment.     

Barley–legumes rotations for semi-arid areas of Lebanon

In arid and semi-arid areas of West Asia and North Africa, including the northern Bekaa Valley of Lebanon, farmers have been increasingly practicing continuous barley cultivation. The objectives of the study were to (1) determine whether barley monoculture is unsustainable¹, (2) ascertain if barley and total dry matter yields can be increased and sustained by including a legume crop in the rotation, and (3) determine which barley–legume rotations are more productive. The trial was set up in a randomised complete block design with two replicates under rain-fed conditions in 1994–1995 at the Agricultural Research and Educational Center (33°56′ N, 36°5′ E, 995 m above sea level). Eight two-phase barley-based rotations were compared: barley in rotation with barley, lentil, common vetch, bitter vetch, common vetch for grazing, medics for grazing, common vetch for hay, and common vetch with barley for hay. Seed and straw were harvested from barley and legumes in the first four rotations. Relative to the trial mean, seed and straw yield under barley monoculture slumped in 1997–1998 and did not recover since then. Infestation of wild barley was a cause of this yield decline. Barley–legume rotations yielded 44–80% more barley grain and 27–53% more barley straw than the barley monoculture over the 6 years (1995–1996 to 2000–2001). Furthermore, in the legume phase, common and bitter vetch gave higher seed yield than barley monoculture. Thus, all barley–legume rotations, except barley–medics, yielded more total dry matter than barley monoculture on the basis of per rotation cycle. Among the barley–legume rotations, the barley-common vetch for seed rotation gave the highest and most stable dry matter yield. In conclusion, barley monoculture was unsustainable, but barley yields could be increased and sustained by including legumes in the rotation. Farmers in semi-arid areas of Lebanon should discontinue practicing barley monoculture and adopt a barley–legume, such as common vetch, rotation.     

玉米秸秆还田条件下麦田氮素运转和籽粒产量对氮肥的响应

为给秸秆全部还田条件下豫北麦玉两熟高产地区冬小麦合理施用氮肥提供理论依据,以周麦18和济麦22为试材,于2011-2013年研究了不同施氮处理(小麦全生育期不施氮肥,及底施纯氮120 kg/hm2基础上拔节期分别追施0,60,100,140,180,210 kg/hm2)下麦田土壤和植株氮素含量的动态变化,分析了不同追氮量对植株氮素吸收、麦田氮肥利用率和籽粒产量的影响。结果表明,小麦植株氮素吸收积累和籽粒产量随施氮量的增加呈单峰曲线变化,周麦18和济麦22分别在220,260 kg/hm2和120,180 kg/hm2施氮量下植株氮素吸收积累达到峰值,籽粒产量较高。麦田氮流失量随施氮量增加呈先升后降变化趋势。秸秆还田配施适量氮肥能够显著提高氮肥偏生产力、氮肥农学利用率;随着施氮量的持续增加氮肥偏生产力、氮肥农学利用率显著降低。综合来看,玉米秸秆还田条件下兼顾氮肥效率和籽粒产量,豫北麦玉两熟区周麦18适宜的氮肥配施量为220~260 kg/hm2,种植济麦22适宜的氮肥配施量为120~180 kg/hm2。     

Transfer of Grain Legume Nitrogen within a Crop Rotation Containing Winter Wheat and Winter Barley

In a crop rotation trial, conducted from 1985 to 1988 at TU-Munich's research station in Roggenstein, the transfer of grain legume nitrogen was evaluated in crop rotations containing fababeans and dry peas as well as oats (reference crop) and winter wheat and winter barley as following crops. The results obtained can be summarized as follows: Dinitrogen fixation by fababeans ranged from 165 to 240 kg N ha¹, whereas N₂-fixation by peas amounted from 215 to 246 kg N ha^?1. In all seasons the calculated N-balance where only grain was removed was positive, with a net gain being on average 106 (peas) and 84 (fababeans) kg N ha^?1. After the harvest of peas 202 kg N ha^?1 remained on the field on average over seasons (158 kg N ha^?1 in the above ground biomass and 44 kg N ha^?1 as NO₃-N in 0–90 cm depth). As compared to peas, fababeans left 41 kg N ha^?1 less due to smaller amounts of nitrogen in the straw. After oats very small amounts of residual nitrogen (33 kg N ha^?1) were detected. After the harvest of grain legumes always a very high nitrogen mineralization was observed during autumn especially after peas due to a close C/N-relationship and higher amounts of nitrogen in the straw as compared to fababeans. In comparison with fababeans, N-mineralization after the cultivation of oats remained lower by more than 50%. During winter, seepage water regularly led to a considerable decrease of soil NO₃-N content. The N-leaching losses were especially high after cultivation of peas (80 kg N ha ^?1) and considerably lower after fababeans (50 kg N ha^?1) and oats (20 kg N ha^?1). As compared to oats, a higher NO₃-N content in soil was determined at the beginning of the growing period after preceding grain legumes. Therefore, winter wheat yielded highest after preceding peas (68 dt ha^?1) and fababeans (60 dt ha^?1) and lowest after preceding oats (42 dt ha^?1). The cultivation of grain legumes had no measurable effect on yield formation of the third crop winter barley in either of the growing seasons.     

前茬冬小麦栽培措施对后茬夏玉米光合特性及产量的影响

为了明确前茬冬小麦施氮和种植方式对后茬夏玉米光合特性及产量的影响,于2013-2015年华北平原冬小麦-夏玉米轮作区进行裂区试验。冬小麦施氮112.5 kg/hm2(N1)和225.0 kg/hm2(N2)为主处理,冬小麦等行距(U)改为夏玉米等行距(UR),20+40沟播(F)改为垄作(BP)的种植方式为副处理。结果表明,与UR和N1相比,BP和N2提高夏玉米叶面积指数(LAI)、叶绿素含量指数(CCI)、净光合速率(Pn)及干物质重(DM),且减缓LAI、CCI和Pn后期降低幅度。冬小麦季,与U相比,F种植方式增产3.1%、穗数提高6.9%、穗粒数提高2.4%。与N1相比,N2处理增产5.0%、穗数提高13.8%、穗粒数提高4.9%;夏玉米季,与UR比,夏玉米BP种植方式增产7.1%、穗粒数提高2.4%、收获指数提高5.9%。与N1相比,N2处理增产13.0%、穗粒数提高9.2%、收获指数提高11.9%。在华北冬小麦-夏玉米轮作区,冬小麦季施氮225.0 kg/hm2的条件下,氮肥后效明显,结合沟播冬小麦收获后在垄上直播夏玉米的种植方式是一种全程简化、高效、丰产的栽培措施,在华北平原冬小麦-夏玉米轮作区有很高的实践意义。     

Das optimale N-Angebot im Frühjahr bei unterschiedlicher Keimdichte von Winterweizen

The optimal N-supply in spring for different plant densities of winter wheat
The influence of plant density (plt./m²) on the optimal N-supply in spring (N_min-content + N-fertilization) has been tested at three sites. The different plant density was produced by different seed rates in autumn of about 150, 250, 350, 450 and 550 grains/m². The N-supply in spring was - apart from a non-fertilized field (N_min-content) 80, 100, 120, 140 and 160 kg N/ha. Additionally, 80 kg N/ha were applicated as N-topdressing. Moreover the optimal N-supply in spring has been tested on a winter wheat field thinned out due to winterkilling. In detail we got the following results:
1. The reduction of the N_min-content due to the N-uptake by the plants slowed down in accordance with minor plant density.
2. The same N-supply in the soil produced a higher N-supply per individual plant in accordance with decreasing plant density and lead to a considerable increase of N-nutrition.
3. Thin crops showed a higher tillering. The differences in plant density between 150 and 550 plt./m² in spring diminished to about 90 ears/m² at harvest.
4. Independently of plant density the maximum yield was obtained by a N-supply (N_min+ N-fertilization) in spring of about 120 kg/ha N. Due to the abundant N-nutrition of the individual plants and the minor increase of yield a higher N-supply is not necessary with a minor plant density.
5. Essentially the yield level was only diminished with the lowest plant density (100-140 plt./m²).     

长期定位施肥对土壤有机质、不同形态氮含量及作物产量的影响

通过长期定位试验,研究不同施肥处理对河北省低平原区土壤有机质、不同氮形态含量及作物产量的影响,旨在为该区冬小麦–夏玉米轮作系统秸秆全量还田下土壤肥力和作物产量的提高提供理论依据。结果表明,经过36个小麦玉米轮作周期的不同施肥处理后,与不施肥处理（CK）相比,施肥可以提高土壤有机质和全氮含量,且随化肥施用量的增加而逐渐增加。在化肥施用量≤N 360kg/hm²+P₂O₅ 240kg/hm²时,秸秆还田较不还田可显著提高土壤有机质和全氮含量,在化肥施用量为N 540kg/hm²+P₂O₅ 360kg/hm²时,增加速度减缓。与CK相比,长期施肥提高了土壤碱解氮和硝态氮含量,而对土壤铵态氮含量没有显著影响。单施化肥时,表层土壤碱解氮和硝态氮含量随氮肥施用量的增加而增加;在秸秆还田下,N360+P240+S9000处理表层土壤碱解氮和硝态氮含量最高。施肥显著提高了作物产量,单施化肥处理,小麦、玉米产量均随施肥量的增加而逐渐增加;秸秆还田条件下,小麦产量在化肥施用量≤N 360kg/hm²+P₂O₅ 240kg/hm²时较单独施用化肥的处理增产。由以上结果可知,长期施肥可提高土壤肥力,增加土壤有机质和全氮含量,适宜的氮肥施用量配合秸秆还田可固持土壤有机碳和全氮,过量氮肥不利于土壤有机质的累积。长期单施化肥或化肥配合秸秆还田均可提高土壤碱解氮和硝态氮含量,对土壤铵态氮含量无显著影响。长期施肥可提高作物产量,在秸秆还田条件下,化肥施用量为N 360kg/hm²+P₂O₅ 240kg/hm²时,增产效果较好。     

Zur Eignung des Kornguts unterschiedlich stickstoffgedüngter Getreidebestände als Rohstoff für die Bioethanolproduktion

The Suitability of Grains from Cereal Crops with Different N Supply for Bioethanol Production
The properties of grains of different small grain cereals, produced under increasing N-supply levels, for conversion into bioerhanol were investigated. Grain material of winterwheat, -rye and -triticale, two cultivars each, was used At two locations, field experiments comprising several N-fertilization levels between 0 and 180 kg N/ha were conducted. The main parameters analysed were the bioethanol output (1 bioethanol/dt grain dry matter) and the bioethanol yield (1 bioethanol/ha), both under addition and without addition of technical enzymes. Furthermore, the falling numbers, the protein content and die autoamylolytic quotient (AAQ) were determined. AAQ means the autoamylolytic bioethanol output related to die output under addition of technical enzymes. With a rising N-supply, yields/ha and die protein contents of grain increased differently. Combined with increasing protein contents, decreasing bioethanol outputs were measured, particularly with wheat, to a smaller extent with triticale, and to an even lesser extent with rye. Only with wheat were die AAQ-values significantly reduced as a consequence of rising N-supply levels. In interaction with growing conditions, cultivars and N-levels, the bioethanol yields/ha of rye and triticale equalled or even surpassed the yields of wheat, particularly under autoamylolytic-conversion processing conditions.     

Contribution of cultivar,fertilizer and weather to yield variation of winter wheat over three decades: A case study in the North China Plain

Long-term field measured yield data provides good opportunity to assess the impacts of climate and management on crop production. This study used the yield results from a long-term field experiment (1979–2012) at Luancheng Experimental Station in the central part of the North China Plain (NCP) to analyze the seasonal yield variation of winter wheat (Triticum aestivum L.) under the condition of sufficient water supply. The yield change of winter wheat over the last 33 growing seasons was divided into three time periods: the 1980s, the 1990s, and the years of 2001–2012. The grain yield of winter wheat during the 1980s was relative stable. During the 1990s, the annual yield of this crop was continuously increased by 193 kg/ha/year (P < 0.01). While for the past 12 years, yield of winter wheat was maintained at relative higher level, but with larger seasonal yield variation than that back in 1980s. CERES-Wheat model was calibrated and was used to verify the effects of management practices on grain yield. Seven scenarios were simulated with and without improvements in management. The simulated results show that the yield of winter wheat was decreased by 5.3% during 1990s and by 9.2% during the recent 12 seasons, compared with that during 1980s, under the scenario that the yield of winter wheat was solely affected by weather. Seasonal yield variation caused by weather factors was around −39% to 20%, indicating the great effects of weather on yearly yield variation. Yield improvement by cultivars was around 24.7% during 1990s and 52.0% during the recent 12 seasons compared with that during 1980s. The yield improvement by the increase in soil fertility and chemical fertilizer input was 7.4% and 6.8% during the two periods, respectively. The initial higher soil fertility and chemical fertilizer input might be the reasons that the responses of crop production to the further increase in chemical fertilizer were small during the simulation period. Correlation analysis of the grain yield from the field measured data with weather factors showed that sunshine hours and diurnal temperature difference (DTR) were positively, and relative humidity was negatively related to grain yield of winter wheat. The climatic change trends in this area showed that the DTR and sunshine hours were declining. This type of climatic change trend might further negatively affect winter wheat production in the future.     

秸秆还田与生物炭配施对麦-玉轮作体系产量和氮素利用率的影响

通过探究秸秆还田与生物炭配施对麦-玉轮作体系产量和氮素利用率的影响,为黄褐土粮食生产科学施肥提供指导。本研究选取不施肥(CK)、单施生物炭(B)、单施化肥(NPK)、化肥配施秸秆(NPKS)、化肥配施生物炭(NPKB)和化肥配施生物炭和秸秆处理(NPKBS),分析不同处理对作物产量、养分含量和氮肥利用率的影响。结果表明：秸秆与生物炭配施化肥均可显著提高作物穗粒数、产量、土壤全氮、碱解氮、植株籽粒氮积累量;秸秆与生物炭配施化肥均可以显著提高氮素利用率,且小麦利用率高于玉米,真实利用率较当季利用率提高了17.72%~37.43%,其中化肥配施生物炭和秸秆效果最好。综上,化肥配施生物炭和秸秆可以显著提高作物产量,提高氮素真实利用率。     

滴灌条件下秸秆覆盖和土壤含水量对冬小麦灌浆特性的影响

为阐明滴灌条件下秸秆覆盖和土壤含水量以及两因素交互作用对冬小麦籽粒灌浆、产量形成的影响,以冬小麦矮抗58为试验材料,设计了秸秆处理(覆盖T、不覆盖T0)与土壤相对含水量(40%(W1)、50%(W2)、60%(W3)、70%(W4)4个水平)两因素裂区试验。结果表明:Richards方程拟合秸秆覆盖和水分调控下冬小麦籽粒灌浆过程的决定系数在0.977 5~0.999 6,达到极显著水平。秸秆覆盖和水分调控间的交互作用对除最大灌浆速率和平均灌浆速率(V)外其他冬小麦籽粒灌浆特征参数的影响达到显著或极显著水平。其中,秸秆覆盖下土壤相对含水量60%(TW3)处理组合具有最长的灌浆持续期T(51.91 d),最长的灌浆中期持续期T_2(15.230 d)和灌浆后期持续期T_3(26.556 d),最大的灌浆中期灌浆速率R_2(0.897 mg/d)和灌浆后期灌浆速率R_3(1.365 mg/d)。产量、水分利用效率和耗水量的二次曲线关系表明,在耗水量240~270 mm可达到产量与水分利用效率双高的效果。本试验中以秸秆覆盖与土壤相对含水量60%(TW3)处理组合水分利用效率最高(29.02 kg/(mm·hm~2)),较秸秆覆盖下土壤相对含水量的70%(TW4)提高了5.30%;产量为7 097.7 kg/hm~2,与TW4处理组合差异不显著。