Nitrogen Requirements at Different Growth Stages of Short-duration Pigeonpea (Cajanus cajan L. Millsp)1

The response to N fertilization of a short-duration pigeonpea genotype, ICPL 87, was studied in the field to assess the scope for genetically improving symbiotic N₂ fixation by pigeonpea. The field study was undertaken during 1985, 1986 and 1987 growing seasons on Vertisol and Alfisol at ICRISAT Center (peninsular India), Inceptisol at Gwalior (central India) and Entisol at Hisar (northern India) in as non-limiting environmental conditions as possible. Nitrogen fertilizer was applied to the soil at various growth stages to determine when N becomes most limiting. There was a significant response in grain yield to fertilizer N applied at flowering in Vertisol but not in Alfisol, Inceptisol or Entisol. This suggests that biological N₂ fixation by short-duration pigeonpea was not adequate to meet N requirements of the crop grown in Vertisol but that it was probably adequate in the other three soil types. These results are discussed in relation to the nodulation and acetylene reductase activity of pigeonpea and also N mineralization potential of different soils. It can be concluded that there is a need for genetic improvement of N₂ fixing ability of short-duration pigeonpea grown on heavy textured soils such as Vertisols.     

Effect of Integration of Fertilizer and Green Manure Nitrogen on Yield Attributes, Nitrogen Uptake and Yield of Lowland Rice (Oryza sativa L.)

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, India, during the wet seasons of 1992 and 1993 to study the effect of full and partial substitution of fertiliser N with green manure N (Sesbania rostrata) on nitrogen uptake, yield attributes and yield of rice. The experiment consisted of eight treatments with two levels of N (100 and 200 kg ha⁻¹) and three sources of N application viz., fertilizer, integrated (1:1 fertilizer and green manure N) and green manure N compared to the recommended practice (150 kg fertilizer plus 6.25 t ha⁻¹ (72 kg N) green manure) and a no N control. Nitrogen application markedly increased the N uptake. Combined use of the two N sources at 200 and 222 kg N ha⁻¹ and of single fertilizer N at 200 kg N ha⁻¹ recorded the maximum N uptake, increased the yield attributes such as number of panicles per unit area, weight per panicle, number of total and filled grains per panicle and test weight. At 200 kg N ha⁻¹ full substitution of N by green manure reduced the grain yield but only partial substitution of N by green manure resulted in almost similar yield as single fertilizer N. Thus 200 kg N ha⁻¹ applied in equal proportions of fertilizer and green manure N can be recommended for medium duration rice cultivars.     

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.     

Stickstoffaufnahme und Stickstoffrückstände von Hauptfrucht-und Ausfallrapsbeständen

Nitrogen Uptake and Nitrogen Residuals of Winter Oil-Seed Rape and Fallout Rape
The objective of the investigation was a study of the relationship between seed dry-matter production and vegetative dry-matter production in oil-seed rape crops and their dependence on the production conditions. In addition to the relationship between the N-uptake during the vegetation period and the N-residue after harvest was of major interest. Furthermore the potential for N-uptake in fallout rape was measured. Over two vegetation periods factorial field experiments with winter oil-seed rape, cv. Lirabon, different drilling techniques and different nitrogen fertilization levels were tested. Measured traits were: the dry-matter accumulation including root mass and fall-off leaf-material mass, the N-uptake of both the oil-seed crops and the fallout rape stands, and, simultaneously, the soil NO₃-N content. Finally the harvest indices and the N-harvest indices were calculated.
Combined with a N-uptake of up to 330 kg N/ha, oil-seed rape crops produced up to 200 dt dry matter/ ha. At seed yield levels of 33dt/ha (d.m.), harvest indices varied from 0.14—0.23 and N-harvest indices varied from 0.30–0.50. As a result of the residue of vegetative plant material at harvest, leaf losses before harvest and the soil NO₃-N-contents at harvest up to 275 kg N/ha remained in the field. After the harvest of oil-seed rape, the soil NO₃-N-contents were quickly reduced by emerging and growing fallout rape stands. However, following soil-preparation measures in the autumn, a continuous rise in the soil NO₃-N-content was observed.     

Evaluation of N Fertilizer Rate and Timing and Wheat Cultivars on Soil Residual Nitrates

Nitrogen (N) fertilizer management for production of bread quality wheat may increase nitrate residues in the soil. To assess soil nitrate levels associated with bread quality wheat ( Triticum aestivum L.) production in Eastern Canada, an experiment was conducted for 2 years at each of two sites in Québec. Four cultivars (Columbus, Katepwa, Max and Hege 155-85), four N levels (0, 60, 120 and 180 kg N ha⁻¹) and two N timings (all at seeding time or 60 % at seeding and 40 % at anthesis) were combined in a factorial arrangement on a Bearbrook clay and a Ste-Rosalie clay. Residual soil NO₃-N levels were measured in the 0–20 and 20– 60 cm soil layers. The cultivars used have potential as bread wheats. Cultivar effects on soil nitrate levels existed only in the Ste-Rosalie soil, suggesting that the cultivars used were better adapted to the conditions on the Bearbrook soil. Changes in soil NC₃N levels over winter indicated that mineralization had occurred. Calculated balance-sheet values were larger than measured residual NO₃-N in the autumn of each year, indicating that NO₃-N was lost from the systems, possibly due to denitrification. Potential increases in, and thus potential pollution from, residual soil NO-N existed only at the 180 kg N ha⁻¹ level. Overwinter changes in soil NO₃-N levels were proportional to the inverse of the fall NC₃N levels. Differences between sites were large for many of the variables measured.     

酿造高粱肥料高效利用研究

为了探讨本栽培区域 N、 P、 K肥对酿造高粱产量的影响, 寻求获得高产的 N、 P、 K肥配方, 本试验采用 “3414” 设计方案, 以 ‘晋杂 23号’ 为试验品种, 在山西省农科院经济作物研究所试验田研究了不同N、 P、 K肥配方对试验品种农艺性状及产量的影响。结果表明： 不同施肥处理高粱农艺性状、 穗粒重、 千粒重都高于对照(N₀P₀K₀), 但方差分析表明差异不显著; 在一定的肥力基础上, 增加肥料投入比不施肥可获得较高产量; 施用氮肥和磷肥对于提高籽粒产量具有显著的作用, 但随着氮肥施用量的增加, 高粱籽粒产量显著降低; 在本试验条件下, 以 N 施用量为 96 kg/hm², P₂O₅施用量为 76 kg/hm², K₂O 施用量为60 kg/hm²是高粱获得高产量、 低成本、 高收益的合理配方。     

Seasonal Changes in Nitrate Reductase Activity and Nitrogen Contents of Upland Rice at Low and Optimum N Fertility

A field experiment was conducted at the Livestock Research Centre of G. B. Pant University of Agriculture and Technology, Pantnagar, India during the wet season (June—October) of 1980 with the objectives of characterizing the seasonal changes in in vivo nitrate reductase activity (NRA) and N contents of upland rice cultivars grown under rainfed condition at low (0 kg N/ha) and optimum (80 kg N/ha) N fertility.
In vivo NRA increased initially up to panicle initiation stage (50 days after sowing) and declined, thereafter, until 90 days. Leaf NO₃-N content paralleled with in vivo NRA throughout crop season. Total N content of leaves and stem declined with advance in crop age, whereas panicle N content increased with the crop development. Optimum N fertility (80 kg N/ha) always resulted in higher NRA, NO⁻₃ and total N contents of rice plants.     

施氮量对酿造高粱产量和氮素利用率的影响

为了实现酿造高粱氮肥合理高效利用,以晋杂22号为试验品种,研究了6种氮肥施用量(0,75,150,225,300,450 kg/hm~2)对酿造高粱产量和氮素利用率的影响。结果表明,在施氮0~450 kg/hm~2,施用氮肥有效地增加了高粱产量和净利润,但随着施氮量的增加产量先升高后降低,其关系可表示为y=-0.037x~2+17.759x+5 874.41(R2=0.878 1)。随着施氮量的增加高粱氮肥偏生产力和氮肥利用率显著降低;氮素吸收效率逐渐降低;氮素利用效率大体呈下降趋势;当施氮量为225 kg/hm~2时,高粱产量、净利润最大,极显著高于不施氮处理,增产率达37.64%;氮肥农学利用率和氮肥偏生产力分别为9.96,36.42 kg/kg,氮肥利用率可达到38.70%,且氮平衡为3.07,大体上满足氮素平衡。综合分析各项指标,施氮量为225 kg/hm~2是酿造高粱晋杂22号实现高产、高效益、较高氮肥利用率的适宜氮量。     

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).     

Vorkommen von Regenwürmern in landwirtschaftlich rekultivierten Flächen in der Niederrheinischen Bucht

Nitrogen dynamics under a pasture on marchy soil
The nitrogen dynamics were studied on the drainage experimental field of the former grassland research and march experimentation station of Lower Saxony. Four variants applying different nitrogen festilization regimes, from 0 up to 380 kg N/ha/a, were investigated. Nitrogen concentrations were measured by analysing soil samples from different depths for NH₄ und NO₃ contents. Balancing the nitrogen flows the N-output in the forage, the drainage outflow, the netimmobilization, and the N-input by fertilization, biological N-fixation, balk deposition and animal excrements were realized. Nitrogen replacements through the soil profile and nitrate losses in the drainage outflow were relatively low. High watercarrying capacity of the soil and high water consumption by the pasture allow only small rates of displacement of nitrogen. No relevant amounts of mineral nitrogen were found in the soil during the vegetation period because of high nitrogen takeup by the plantbiomass. A certain accumulation of nitrate was observed in late autumn. The concentration however remained unrelevant with respect to goundwater polution. In the drainage water maximal 8 kg of nitrate were leached under the highest fertilized variant. The saldo of the nitrogen balance indicates considerable amounts of nitrogen being lossed by denitrification and ammonia volatilization.     

大棚秋番茄直播高产施肥措施数学模型的研究

采用“311－B”二次回归最优设计，以氮、碗、钾肥为供试因子，番茄产量为目标函数，对番茄高产数学模型进行了研究。根据模型得出最佳施肥量为；尿素227kg/hm^2，过磷酸钙751kg/hm^2，硫酸钾142kg/hm^2，产量可达63364.10kg/hm^2，利润99366.6元／hm^2，并对氮磷钾单因素效应及交互作用作了具体剖析。     

Nitrogen Mineralization Rates and Kinetics in Soils Freshly Amended with Green Manures

Long term incubation studies to determine the nitrogen (N) mineralization rates and kinetics in soils freshly amended with some commonly used green manures such as Sesbania rostrata. Gliricidia maculata. Leucaena leucocephala and Azolla pinnata are scarce. A long term aerobic study was, therefore, conducted by incubating soils freshly amended with the above-mentioned green manures in PVC columns at 35 ± 1 C and with 0.01 Mpa moisture content. The soils were then leached at periodic intervals for up to 36 weeks.
The N-mineralization rates were greatest during the first week and decreased with time in all soils. The green manure amended soils leached 247 mg kg⁻¹ more NO₃+ NO₂– N than the unamended control. In general, the total N mineralized (mean 61%) was almost twice that of net N mineralized (mean 30%) in the amended soils. The percent N mineralized (total and net), however, varied with the nature of green manure incorporated into the soil. It was greatest in the soil amended with sesbania and lowest in the soil amended with azolla. The kinetic parameters derived using the double exponential model indicated that green manure amended soils possessed significantly higher N-mineralization potentials and rate constants compared to the unamended control. The kinetic parameters also varied with the nature of green manure incorporated into the soil. Among the various parameters lignin content, lignin to N ratio and lignin + polyphenol to N ratio of the green manures were the key factors governing the rate of decomposition and subsequent N mineralization from the amended soils.     

大白菜-辣椒轮作中土壤养分限制因子及平衡状况研究

采用肥料定位试验与土壤养分系统研究法相结合的方法,探讨北方裸菜地主要种植方式大白菜—辣椒轮作中土壤自然供氮、磷、钾、锌、硼能力,土壤氮、磷、钾的收支平衡及相应土壤养分的消长状况。主要结果:大白菜—辣椒轮作中:全肥处理(NPKZnB)大白菜和辣椒的年均产量分别为111.6,23.7 t/hm2,-N、-P、-K的相对产量分别为全肥的56.7%,63.6%,84.7%;辣椒上-N-、P-、K、-Zn-、B的相对产量分别为全肥的45.8%,45.9%,67.7%,88.0%,84.9%,差异均达到显著水平。大白菜限制产量的因子为:N>P>K,辣椒为:N,P>K>Zn,B。P2O5用量180kg/hm2,K2O用量300 kg/hm2的处理,土壤磷和钾养分分别盈余70.3%和2.0%,土壤有效磷(Olsen-P)、有效钾分别年均增加3.3和37.2 mg/kg,积累的土壤有效磷和有效钾分别占土壤磷和钾积累量的7.1%和28.3%。大白菜茬口N,P2O5,K2O推荐用量为225,90,150 kg/hm2,辣椒茬口分别为337.5,213,337.5 kg/hm2并配合施用一定的锌和硼肥。     

化肥减量条件下不同有机肥用量对油菜养分利用和产量的影响

以油菜品种湘油420为供试材料,采用田间试验,研究了化肥减量25%条件下,配施不同用量（1125~4500kg/hm²）有机肥对油菜产量、干物质积累以及养分积累的影响,以常规施肥,即化肥不减量且不施有机肥为对照。结果表明,化肥减量25%配施有机肥可显著提高单株角果数、植株干物质和养分积累量,从而提高油菜产量,且随着有机肥用量的增加而增加,而经济效益仅在有机肥用量较低时（1125kg/hm²）有所增加。化肥减量25%配施有机肥处理比常规施肥（FFP）处理增产25.2%~78.5%,比化肥减量25%未配施有机肥（F75%）处理增产43.9%~105.1%;根据有机肥用量与产量之间的回归方程,化肥减量25%时仅配施675kg/hm²有机肥可弥补因化肥减量带来的产量损失。与FFP和F75%处理相比,化肥减量25%配施有机肥处理均显著增加油菜干物质和氮磷钾积累量。化肥减量25%配施1125kg/hm²有机肥处理的经济效益最高,为5789元/hm²,比FFP处理增加74元/hm²,比F75%处理增加519元/hm²。综上可得,有机无机肥配施可促进养分积累和油菜生长,提高菜籽产量,通过配施有机肥可实现化肥减量25%的目标,且本区域有机肥配施的适宜用量为1125kg/hm²。     

Effects of Nitrogen on Dry Matter Accumulation and Productivity of Three Cropping Systems and Residual Effects on Wheat in Deep Vertisols of Central India

A field experiment was conducted on deep vertisols of Bhopal, India to study the effects of three levels of nitrogen (N), namely 0, 75 and 100 % of the recommended dose of nitrogen (RDN), on the dry matter accumulation (DMA) and productivity of three cropping systems (sole soybean, sole sorghum and soybean + sorghum intercropping) during the rainy season and their residual effect on the subsequent wheat crop during the post-rainy season. During the rainy season, sole sorghum was found to have significantly higher DMA and productivity in terms of soybean equivalent yield (SEY) than sole soybean or soybean + sorghum intercropping. Increasing the N dose from 0 to 100 % RDN significantly improved the DMA and SEY. At a low fertility level (N₀), soybean + sorghum intercropping was found to be more productive, while at a high fertility level (100 % RDN), sole sorghum was more productive than the other two cropping systems. However, during the post-rainy season, sole soybean as the preceding crop gave the highest DMA and seed yield of wheat, which were similar to those found with soybean + sorghum intercropping. Sorghum followed by wheat gave the lowest DMA and seed yield of wheat. Application of 100 % RDN irrespective of cropping system during the preceding crop improved the DMA of wheat but not its seed yield. However, N applied to the wheat crop significantly increased its DMA and seed yield.     

An Evaluation of Fertilizer and Soil Nitrogen Uptake by Wheat

Nitrogen utilization and uptake patterns of wheat was studied using ¹⁵N labelled fertilizer at four rates of application. Plants harvested at maximum tillering and at flowering indicated that plant N levels stabilized with time. Fertilizer N uptake and utilization of added fertilizer increased with time. However, uptake of soil N was not affected by rates of fertilizer at early stages. Increases were observed only at higher rates at the later harvest.     

施氮量对酒用糯高粱品种红缨子产量及氮素吸收利用的影响

为探明贵州地区糯高粱氮肥高效利用的施肥技术,以品种红缨子为研究对象,设置0（N0）、120（N120）、240（N240）、360（N360）、480（N480）、和600kg/hm2（N600）6个施氮水平,研究了糯高粱的产量和氮素吸收利用特征。结果表明,糯高粱产量、干物质积累总量和氮素积累总量随氮素水平的提高呈先升高后降低的趋势,增施氮素较不施氮素能够显著提高糯高粱的产量、干物质积累总量和氮素积累总量,其中以N240处理增幅最大,较N0处理分别增加28.87%、35.83%和49.62%。随着施氮量的增加,糯高粱氮素表观回收率、氮肥农学利用率、氮肥利用率、氮肥偏生产力和产投比呈下降趋势。利用二次多项式和平方根模型分别拟合糯高粱产量和效益的施氮效应,当施氮量分别为294.5和252.6kg/hm2时产量最高,施氮量分别为168.2和132.7kg/hm2时效益最大。兼顾产量、效益及氮肥利用效率,120~240kg/hm2的氮肥施用量是适宜的。     

Effects of Salinity and Mixed Ammonium and Nitrate Nutrition on the Growth and Nitrogen Utilization of Barley

The absorption and utilization of nitrogen (N) by plants are affected by salinity and the form of N in the root medium. A hydroponic study was conducted under controlled conditions to investigate growth and N uptake by barley ( Hordeum vulgare L.) supplied with five different NH₄⁺-N/NO₃⁻-N ratios at electrical conductivity of 0 and 8 dS m⁻¹. The five NH₄⁺-N/NO₃-N ratios were 0/100, 25/75, 50/50, 75/25 and 100/0, each giving a total N supply of 100 mg N l⁻¹ in the root medium. A mixed N supply of NH₄⁺ and NO₃⁻ resulted in greater accumulation of N in plants than either NO₃⁻ or NH₄⁺ as the sole N source. Plants produced a significantly higher dry matter yield when grown with mixed N nutrition than with NH₄⁺ or NO₃⁻ alone. Total dry matter production and root and shoot N contents decreased with increasing salinity in the root medium. The interaction between salinity and N nutrition was found to be significant for all the variables. A significant positive correlation (r=0.97) was found between nitrogen level in the plant shoot and its dry matter yield.     

海南儋州市水稻肥料效应研究

为探明海南儋州地区水稻土壤供肥能力和氮磷钾肥的利用率,为海南儋州地区测土配方施肥提供依据,我们采用“3414”试验方案,进行了水稻田间试验,并建立了三元二次施肥模型。研究结果表明,尿素（氮肥）的利用率为40.1%,过磷酸钙（磷肥）利率15.2%,氯化钾（钾肥）的利用率37.1%。根据三元二次施肥模型,求得最佳施肥量N 159.6kg/hm2、P2O5 40.8kg/hm2、K2O 55.2kg/hm2。     

A survey on actual agricultural practices and their effects on the mineral nitrogen concentration of the soil solution

In intensive integrated crop-livestock farming systems, the surplus of N at the farm scale may be large and reflects on the N balance at the field scale. A study was conducted to assess the N fertilizer efficiency in four private farms in intensively cropped areas of NW Italy, and to monitor the effects of agricultural practices on the mineral N concentration of the soil solution, sampled every 2 weeks for 2 years and considered as an indicator of potential leaching. Two cultivation systems were compared in each farm, one involving continuous maize rotation, the other assuring a continuous soil cover (permanent meadow or winter cereal-maize double cropping system). The fertilization level in the arable crops was high (369–509 kg N ha⁻¹ year⁻¹) compared to the crop removals, and resulted in a low efficiency, as indicated by the four examined efficiency indexes (calculated N surplus, N removal-fertilizer ratio, N apparent recovery, N use efficiency). The soil-water-nitrate concentration showed large temporal variations in the range of 1–150 mg l⁻¹ for five out of the eight cropping situations, while concentrations smaller than 10 mg l⁻¹ were always recorded in the meadows and in one of the four soils (Aeric epiaquept). The fertilizer management that characterized each cropping system affected the soil-mineral-nitrate content in shallow arable soils. The longer soil cover duration in double-cropping systems did not result in a reduction of soil N compared to maize as a single crop, not even in winter (the bare-soil intercropping period in maize-based systems). However, the temporal oscillations of the concentration were buffered by the crop cover duration and by the presence of a shallow water table (1 m deep) in the soil profile. The average nitrate content of the soil could be predicted by the N uptake of the crop, the N removal–fertilizer ratio, the soil pH and sand content, however no simple explanatory relationship was found with the experimental factors. Hence, in farm conditions, in the absence of sufficient data for a deterministic model approach, the target of reducing the risk of leaching should be achieved by maximizing the fertilizer efficiency.