Relative efficiency of prilled urea and urea-supergranules in Java citronella (Cymbopogon winterianus Jowitt)

A two-year field study was carried out to compare the efficiency of prilled urea and urea-supergranules in the cultivation of a perennial aromatic grass, citronella (Cymbopogon winterianus Jowitt) in a sandy loam soil. Application of 300kg Nha^–1 year^–1 increased the herb and essential oil yields. Urea-supergranules significantly increased the yields over prilled urea.     

Growth rate,yield and nitrogen uptake response of grain sorghum (Sorghum bicolor (L) Moench) to nitrogen rates in humid subtropics

Field experiments were conducted during wet seasons (June to October) of 1974, 1976 and 1977 to determine the response of newly developed hybrids and varieties of grain sorghum to N fertilization under humid subtropical conditions of Pantnagar in India. In addition to the enhancement in flowering and maturity stages brought about by N application, it also resulted in increased plant dry weight, translocation coefficients, grain yield plant^–1 and grain yield ha^–1. Varietal differences existed with respect to their responses for yield and N uptake to N rates. Most of the entries responded up to 120 kg N ha^–1. Hybrid CSH 5 utilized applied N more efficiently than other varieties.Publication No 1612 of GBPUA and T, Experiment Station, Pantnagar.     

Effect of different sources of iron and sulphur on leaf chlorosis,nutrient uptake and yield of groundnut

The pot experiment conducted in calcareous soil of Saurashtra, India showed that application of lime (20% CaCO₃) and excess water (irrigation at –0.3 bar) to the soil enhanced chlorosis in groundnut leaves caused by induced deficiencies of iron, sulphur and zinc, which was recovered by applying agricultural grade chemicals containing iron, sulphur and zinc. This chlorosis caused 29.8 and 19.1% reduction in pod yield of groundnut due to lime and excess water, respectively in the untreated control pot and 17.1 and 9.6%, respectively in the pot treated with different chemicals.Application of iron sulphate, zinc sulphate, iron pyrite, gypsum, phospho-gypsum, elemental sulphur, wettable sulphur and Fe-EDTA decreased chlorosis and increased chlorophyll and carotenoid contents of leaves, uptake of Fe, S and Zn and pod yield of groundnut significantly. The foliar spray of 0.5% aqueous solution of iron sulphate, zinc sulphate and Fe-EDTA at 20, 35, 50 and 65 days after emergence (DAE) was more effective than their soil applications. The Fe-EDTA corrected only iron chlorosis, and gypsum, phosphogypsum and elemental sulphur only sulphur chlorosis. However, iron sulphate and iron pyrite corrected iron and sulphur and zinc sulphate corrected zinc and sulphur chlorosis. Among the soil amendments, application of iron sulphate and iron pyrite showed better responses to groundnut and showed higher Fe and S uptake than other treatments. The responses of gypsum, phosphogypsum and elemental sulphur were at par. The correlation study showed that pod yield of groundnut was negatively correlated with chlorosis and positively correlated with the chlorophyll and carotenoid contents in groundnut leaves.     

Yield and uptake response of lettuce to cadmium as influenced by nitrogen application

A screen house experiment was conducted to determine the effect of N (0, 50, 100 and 150 mg N kg^–1) and Cd (0, 5, 10, 25 and 50 mg Cd kg^–1) on growth and concentration and uptake of N and Cd in lettuce grown for 70 days. Nitrogen application increased significantly fresh yield, dry matter yield, N concentration and uptake, whereas these parameters were significantly decreased by Cd application at all levels of N. The concentration and uptake of Cd were significantly increased by Cd application at all levels of N. This increased Cd uptake was related to increased availability of Cd in soil. Application of N upto 100 mg N kg^–1 increased Cd uptake, whereas there was sharp reduction in Cd uptake at 150 mg N kg^–1 treatment at all levels of Cd. The plant dilution effects and reduced translocation of Cd from roots to tops or the competition at the root absorption sites at highest level of N seem to be the mechanisms responsible for N suppressed Cd uptake in this study.     

Response to nitrogen application and interval between harvests in five grasses — I Dry-matter yield,nitrogen content and yield,numbers and weights of tillers,and proportion of crop fractions

Effects of five levels of applied nitrogen on field swards of each of five grasses were studied in the year of sowing, in the first full harvest year and part of the second harvest year. The plots were cut at 4-week intervals during the year of sowing; subsequently 4- and 8-week intervals between cuts were compared.Differences between grasses in dry-matter yield response to applied N were sufficiently large to suggest that commercially-important varieties should be tested at more than one level of applied N. In Melle and R v P the percentage increase in weight per tiller due to applying N was much greater, and in Aberystwyth S.24, Sabrina and Aberystwyth S.170 only slightly greater, than the percentage increase in number of tillers. Sabrina had a low number of tillers, with a negative effect of the final increment of applied N on number of tillers. The results for the five grasses in respect of number of tillers, weight per tiller, dry-matter yield, N yield and light penetration all emphasized the case for more frequent defoliation the higher the level of N applied. The application of N greatly increased the proportion of stem in the harvested herbage on 16 September 1977, evidently at least partly by reducing the proportion of stem which escaped defoliation. On that date, with the 8-week interval, the application of moderate amounts of N reduced the N content of the harvested herbage, evidently because of a large reduction in the proportion of green leaf blade and an increase in the proportions of stem and dead leaf blade.     

Effect of nitrogen and water uptake on yield of wheat

For 2 years, field experiments were conducted to study the direct and interactive effects of water and nitrogen uptake at different growth stages on grain yield of wheat, grown on coarse textured alluvial soil of Ludhiana. Twelve treatments comprising 3 irrigation regimes and 4 rates of N were imposed. The N and irrigation regimes showed significant interaction, especially during the drier year. Grain yield was better explained with water uptake and N uptake, when partitioned over different growth stages than with total uptake. The sensitivity factor for water uptake was higher at the reproductive stage ( = 1.60) than at the vegetative ( = 1.05) and maturation ( = 0.38) stages. Contrary, yield was more sensitive to N uptake during the vegetative stage than the reproductive and the maturation stages. Sensitivity of grain yield to water uptake was higher at higher N application rates. Yield predictability was much better (R² = 0.98) when N and water uptake at different growth stages were combined.     

Growth response,yield and yield components of upland cotton (Gossypium hirsutum L) as affected by rates and time of nitrogen application in the Nigerian savannah

Effects of rate and time of nitrogen fertilization on growth, yield and yield components of upland cotton (Gossypium hirsutum L) were studied in two years (1975–76). Four rates of nitrogen application (0, 26, 52 and 78 kg ha^–1) timed at 3 or 8 weeks after sowing were compared. Seed cotton yield components increased significantly with increased N application at least up to 52 kg N ha^–1, with yield increases between 49% and 73%. Seed cotton yield was influenced by treatments mainly through boll number. Both crop growth rate and fruiting were enhanced by nitrogen fertilization. Applying N at 8 weeks (flowering) favoured yield only slightly over that at 3 weeks (thinning), but improved crop growth and fruiting by about 64% and 24%, respectively. There were significant N rate × time interactions in favour of fertilization at flowering. Applying 52 kg N ha^–1 at 8 weeks seems best for cotton in the Nigerian savannah.     

Yield response and nitrogen uptake of pearl millet (Pennisetum americanum (L.) Leeke) cultivars to nitrogen application in the savanna region of Nigeria

Field experiments were carried out during the wet seasons (May to September) of 1980 and 1981 in order to determine the response of five pearl millet cultivars to nitrogen fertilization in savanna region of Nigeria. There were varietal differences in yield and nitrogen uptake in response to nitrogen rates. Most cultivars responded significantly up to 75 kg N ha^–1. Hybrid outyielded other cultivars at both locations each year. Nitrogen use efficiency was highest with the Hybrid, compared to other cultivars.     

十二碳二元酸生产菌培养基碳源与氮源的优化

以热带假丝酵母菌(Candida tropicalis)为试验菌株,在摇瓶发酵培养基础上,对种子培养基及发酵产酸培养基的碳源、氮源进行优化。结果表明:种子培养基最适碳源为葡萄糖,最适氮源为酵母浸粉FM902;菌体产酸培养基最适碳源为蔗糖(w)2%、葡萄糖(w)0.5%,比仅有2%蔗糖的培养基产酸量提高14.5%;最适氮源为0.08%(w)酵母浸粉FM902,比只含酵母浸膏LM902的培养基产酸量提高35.3%。     

不同增效氮肥品种及用量对玉米幼苗生长、光合特性及养分吸收的影响

采用盆栽试验,研究3种增效氮肥(海藻寡糖尿素、腐植酸尿素、聚能网尿素)及其用量对玉米幼苗生长、光合特性及养分吸收的影响。结果显示,3种增效尿素对玉米幼苗生长的促进作用均好于普通尿素,且海藻寡糖尿素对玉米生长的综合促进效果最优;进一步研究显示,海藻寡糖尿素可提高玉米功能叶片叶绿素含量和净光合速率,还能促进玉米对氮、磷、钾的吸收,同等施氮条件下其施用效果优于其他2种增效氮肥。     

Effect of different sources of iron and sulphur on nutrient concentration and uptake by groundnut

The C and N mineralization characteristics of two organic N fertilizers were determined in a soil-less incubation system at three temperature regimes. Protox (derived from activated sewage sludge) initially degraded more rapidly by microbial action compared with dried blood. However, dried blood released more CO₂-C and inorganic N towards the end of the incubation periods. The rate of microbial degradation increased with temperature. Mineralization characteristics of protein-based N sources are discussed in relation to organic N nutrition of vegetable crops.     

Simulation of the effects of nitrogen supply on yield formation processes in winter wheat with the model TRITSIM

An outline of the dynamic winter wheat model TRITSIM is given. The model describes in one-day steps growth, yield formation and development of a crop from post-winter tillering until harvest under various conditions of water and nitrogen supply. TRITSIM is coupled with a simple soil nitrogen model and a soil water model to describe effects of nitrogen and water on yield formation processes. Comparisons between model and experimental results for ontogenesis, grain biomass, nitrogen uptake and soil mineral nitrogen are given for a series of Dutch experiments. Simulations were satisfactory, except for the time course of soil mineral nitrogen.     

包膜控释氮肥对玉米增产效应的研究

采用包膜控释氮肥在玉米上进行肥效试验研究。结果表明,与普通氮肥(尿素)相比,控释氮肥由于其本身控制释放和缓慢释放的特点,能使耕作层土壤速效氮含量在玉米生育期内维持较高的水平,满足玉米生长对氮素的吸收需求,尤其能满足玉米中后期对养分高强度吸收的需求;显著提高玉米生长中后期植株体内氮素含量,加速氮磷钾向籽粒的转移,从而提高生物产量、经济产量和玉米品质。同等和减半施氮量条件下,玉米产量和氮素利用率都有显著提高。     

Effect of irrigation and nitrogen fertilizer on yield,oil content,nitrogen accumulation and water use of canola (Brassica napus L.)

Effects of N application and water supply on yield, oil content and N accumulation by canola, cultivar Marnoo, grown on a heavy clay soil in the Goulburn Murray Irrigation Region were investigated. Treatments were rainfed (R_f) or watered at a deficit of 50 mm (40–60 mm, I₅₀) beginning in the spring. N treatments were 0, 50, 100 or 200 kg N ha^–1 at sowing or as split applications of 20/80, and 50/50 kg N ha^–1 at sowing and rosette, respectively.Yield (Y_g) ranged from 170 to 520 g m^–2. Irrigation and N increased yield in both years. Grain yields were increased by N application on the irrigated treatments when 100 or 200 kg N ha^–1 was applied. Oil concentrations ranged from a maximum of 46.4% in treatment N₀ to a minimum of 40.6% in treatment N₂₀₀ and was inversely related to seed N concentration. Although fertilizer N decreased oil concentration, it increased the yield of oil.Nitrogen accumulation (N_b) limited yield of all treatments and was described by the equation, Y_g = 806[1-EXP(–0.039*N_b)]. This implied a decrease in yield per unit of N_b at the higher rates of fertilizer addition with consequent increases in grain N concentration.The efficiency of water use in the production of grain (WUE_g) and biomass (WUE_b) were 7.5 and 23 kg ha^–1 mm^–1 respectively. Nitrogen additions increased WUE_g and WUE_b in both seasons. Maximum values of 8.9 (WUE_g 1986) and 26.8 (WUE_b 1987) were measured from treatment N₂₀₀. These data suggest that the crops made efficient use of the applied water.     

The effect of nitrogen on root growth and nutrient uptake of young tea plants (Camellia sinensis L.) grown in sand culture

Root growth and nutrient uptake of a tea clone were studied in a sand culture experiment using ammonium sulphate, ammonium nitrate and urea each at 35, 70 and 105 ppm N. Results show that increasing N levels regardless of forms increased the proportion of white roots and decreased brown root weight.As to the composition of the aerial parts (plant tops) enhanced N supply increased concentrations of Ca and NO₃, while K and H₂PO₄ concentration decreased. Use of ammonium sulphate increased the sulphate levels. Increased N level through urea increased Cl concentration, while the reverse was true with both ammonium sulphate and ammonium nitrate. Concentrations of Mg and Na remained unaffected by N fertilization, though the former tended to increase with increased level of N irrespective of forms. The organic acid concentration measured as the difference of sum equivalents of cations and that of anions increased with an increase supply of N in any of the three forms.The white:brown root ratio was correlated positively with growth, Ca:K ratio and organic acid content of plant tops.     

Yield,water use and nitrogen uptake for different water and N levels in winter wheat

In an effort to establish an optimum combination of water and nitrogen for winter wheat a field investigation was carried out on a coarse loamy sand soil during 1984–85 and 1985–86 to assess effects of irrigation regime (IR) and N application on yield, water use and N uptake. The treatments compromised all combinations of three irrigation regimes (IR) based on ratios of irrigation water to cumulative pan evaporation viz.1.2 (I-1), 0.9 (I-2) and 0.6 (I-3) and four rates of N, viz. 0, 60, 120 and 180 kg ha^–1. Grain yield increased with increase in frequency of irrigation. In spite of wide differences in weather during the two years, scheduling of irrigation at IW/CPE = 1.2 gave the highest wheat yield on the coarse-textured soil. During 1984–85, the rainless year, grain yield under I-1 was 20 and 32 per cent higher than I-2 and I-3, respectively. With increasing N rate the yield and water use efficiency increased progressively upto 180 kg N under I-1 and upto 120 kg N ha^–1 under I-2 and I-3 regimes. During 1985–86, the wet year, grain yield response to IR was relatively low. Irrespective of IR, yield increased progressively upto 180 kg N ha^–1 during the wet year. Irrigation water regimes and N application also influenced leaf area index and root growth of wheat. The yield of unfertilized wheat was relatively less affected by seasonal rainfall and IR.Both N uptake and grain yield of wheat were found to increase linearly with increase in water use. Water use efficiency was highest under I-1 regime at all levels of N in the dry season of 1984–85 and under I-3 regime in the wet season of 1985–86. Increase in N uptake with increasing N rates was significantly higher under I-1 than I-2 and I-3 regimes. The N use efficiency being maximum at 60 kg N ha^–1, decreased at higher N levels irrespective of IR.     

Effects of nitrogen source,rate and application time on boronia (Boronia megastigma Nees) leaf nitrogen and flower production

Nitrogen was supplied from two fast release sources, ammonium sulfate ((NH₄)₂SO₄) and calcium nitrate (Ca(NO₃)₂) and a slow release source, isobutylidene diurea (IBDU) to boronia, a new flower crop native to Australia. At lower rates (25 kg per ha), N availability from different sources, as indicated by the leaf N concentration, did not differ within a month after application but three months after application, N availability was higher from IBDU than from (NH₄)₂SO₄ or Ca(NO₃)₂. At 50 or 100 kg per ha, N availability was higher throughout the year from (NH₄)₂SO₄ or Ca(NO₃)₂ than from IBDU, thereby allowing luxury consumption and causing toxicity. The flower yield increased with increasing N rates. Complete doses of all N rates which were applied early during the vegetative growth gave the highest yields and the same N rates applied in split doses at different phases of plant growth decreased the yields. In addition, high N availability during flowering (caused by a split dose) further decreased the yield. At all application times, IBDU gave the highest yield and the differences in yields with (NH₄)₂SO₄ and Ca(NO₃)₂ were not significant. The leaf N concentration associated with maximum yield declined as the plant advanced towards flowering.     

Influence of straw mulching on fertilizer nitrogen use efficiency,moisture conservation and herb and essential oil yield in Japanese mint (Mentha arvensis L.)

In a field study, the influence of organic mulches viz. paddy straw and citronella (Cymbopogon winterianus Jowitt) distillation waste on herb and essential oil yield and fertilizer N use efficiency in Japanese mint (Mentha arvensis L.) were examined for two years. Herb yield (dry weight) increased by 17 and 31% with paddy straw and citronella distillation waste, respectively over the use of no mulch. Essential oil yield also significantly increased due to mulching. A significant response to N was observed with 200 kg N ha^–1 in unmulched plots as against 150 kg N ha^–1 in mulched plots. Mulched soils have been observed to contain 2 to 4% higher moisture as compared to unmulched soils. Nitrogen uptake by plants increased by 18 and 25% over no mulch with using paddy straw and citronella distillation waste, respectively.     

钙镁磷肥复式包膜尿素对冬小麦产量和氮肥效率的影响

通过连续 3年 ( 1999～ 2 0 0 0年 )大田试验 ,研究了钙镁磷肥复式包膜尿素对冬小麦产量、氮效率〔包括 :氮素效率比 ( NER) ,氮吸收效率 ( NUp E) ,氮素使用效率 ( NUE)和氮肥利用效率 ( Nf UE)〕的影响。结果表明 ,钙镁磷肥复式包膜尿素与普通尿素的生物量、籽粒和秸秆量均显著大于对照处理 ;氮素使用效率 ( NUE)和氮肥利用率均显著高于对照。包膜尿素处理的产量和氮效率最高 ,其籽粒、秸秆、生物量平均值比普通尿素处理分别高 9.0 9%～15 .0 6 %、13.11%～ 14 .96 %、11.73%～ 14 .99% ,氮肥利用率高 15～ 16个百分点。在本试验条件下 ,相对于通常氮肥施用量 ( 15 0 kg N/hm2 ) ,少量增加氮肥施用量 (氮肥用量增加 8% )对产量和氮效率 ( NE)没有显著影响 ;而大量增加氮肥施用量 (增加 2 0 % ) ,能明显增加小麦产量、吸氮量和氮肥利用率     

Effects of rate and timing of nitrogen dressings on grain yield formation of winter wheat (T. aestivum L.)

A field experiment with the winter wheat cultivar Donata was carried out on a fine-textured river clay soil in 1978. The rates of nitrogen dressing ranged from 0 to 160 kg N per ha and were split over from one up to three application times: autumn, early spring and late spring.Total above-ground dry matter and grain dry-weight yields ranged from 9.1 to 13.7 tons per ha and from 4.17 to 6.35 tons per ha, respectively. Late top-dressings increased the harvest-index, whereas an autumn dressing had the opposite effect. Number of culms per m², grain weight (mg) and grain number per m² increased from 350 to 430, from 35.5 to 36.8 and from 11 680 to 16 980, respectively, as the nitrogen dosage was raised from 0 to 160 kg N per ha.The linear rate of grain growth ranged from 111 to 172 kg dry matter per ha per day with nitrogen doses from 0 to 160 kg N per ha. Differences in rate of grain growth per unit area were mainly related to number of grains per m². The association between grain number and grain yield was reflected by a correlation coefficient of 0.97 (n = 32). A higher level of nitrogen dressing enhanced the leaf area index and leaf area duration. However, we could not derive an effect of nitrogen on the duration of grain growth.Total nitrogen yield ranged from 71 to 166 kg N per ha and grain nitrogen yield from 54 to 122 kg N per ha with nitrogen dosages of 0 and 160 kg N per ha, respectively. The nitrogen concentration of the grains varied between 1.3 and 2.0 N.An autumn dressing of 40 kg N per ha generally showed only minor effects on yield and yield components. Top dressings during spring resulted in a higher recovery and efficiency of the applied nitrogen. Therefore, it may be concluded from this experiment and literature that on fertile soils an autumn dressing of nitrogen will not be economical, but split-dressings in spring are very beneficial. In particular, a late nitrogen application during the boot stage increased grain number, harvest-index and grain yield as well as protein concentration of the grain.