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1.
The total deposition of sulphur (S) and nitrogen (N) components in Norway during the period 1988–1992 has been estimated on the basis of measurement data of air- and precipitation chemistry from the national monitoring network. There are large regional variations in depositions with highest values in the southwestern part of Norway. Time series analysis of annual mean concentrations of sulphur dioxide (SO2) and sulphate (SO4 ––) in air, non marine SO4 ––, nitrate (NO3 –) and ammonium (NH4 +) in precipitation, shows a significant reduction in the S concentrations both in air and precipitation. In precipitation the concentrations are reduced by 30–45 percent in Southern Norway and 45–55 percent in Central and Northern Norway. Even larger reductions are observed in air concentrations with 50–65 percent reduction in Southern Norway and 65–88 percent reduction further north. For N components there are generally no significant trends in concentration levels nor in precipitation or air. The observed trends are comparable with reported trends in emission.  相似文献   

2.
Farmers are applying very high amounts of N fertilizer (sometimes >900 kg N/ha), commonly (NH4)2SO4, to irrigated potato (Solanum tuberosum, L.) grown on sandy textured soils in the Cappadocia region of Turkey. To obtain information on potato yield, N uptake, N fertilizer residue in the soil and the portion of N fertilizer leached below 200 cm soil depth, nine field experiments were conducted at three different locations in 1992, 1993 and 1994. The N rates used in these experiments were 0, 200, 400, 600, 800 and 1,000 kg N/ha within a completely randomized block design with three replicates. N fertilizer was applied in two equal portions; one at planting and one just before the first irrigation. Although all yield data were used to find out the marketable tuber yield, the N rate response curve and the fate of applied fertilizer N was determined only for the 400 and 1,000 kg N/ha rates. Isotope microplots were established where 15N-labelled (NH4)2SO4 was applied at 5.0 atom % and 2.5 atom % excess enrichments for the 400 kg N/ha and 1,000 kg N/ha rates, respectively. At harvest, marketable and dry tuber yield was determined for all N rates. Dry tuber and leaf plus vine yields were determined for the isotope microplots and they were analysed for the % N and 15N atom % excess. The % N derived from fertilizer and N use efficiency (%NUE) were calculated for the plant samples. The 15N-labelled residue left in 0-200 cm soil was also determined. The amount of N fertilizer leached below 200 cm soil depth was also calculated. 15N-labelled NO3- and total NO3- of the groundwater from wells were determined at different dates. Our results show that the optimum marketable tuber yield was obtained with 600 kg N/ha. Tuber N uptake was increased slightly, while leaf plus vine N uptake increased considerably when the N rate was increased from 400 to 1,000 kg N/ha. The %NUE values decreased nearly by half and the amount of N fertilizer in the 0-200 cm soil layer increased more than 3 times when the N rate was increased from 400 to 1,000 kg N/ha. Nearly half of the applied fertilizer N (45.6%) at 400 kg N/ha and more than half of the applied fertilizer N (60.8%) at 1,000 kg N/ha was still in the 0-200 cm soil layer after harvest. Four times more N fertilizer was leached below 200 cm soil depth when 1,000 kg N/ha N was applied instead of 400 kg N/ha. Our results also indicate that there is a potential contamination of groundwater due to leaching of the applied N fertilizer.  相似文献   

3.
Nitrogen (N) fertilizer is generally the most costly input for winter wheat (Triticum aestivum L.) production. Therefore, it was important to maximize fertilizer use efficiency and minimize N losses to the environment. One of the mechanisms responsible for decreased N use efficiency (NUE) was plant N loss. The objectives of this experiment were to determine fertilizer N recovery in winter wheat when produced for forage and grain, and to quantify potential plant N losses from flowering to maturity in winter wheat. Two long‐term (>25 years) winter wheat (Triticum aestivum L.) N rate fertility experiments (Experiment 222 and Experiment 502) were selected to evaluate 15N fertilizer recovery. Percent 15N recovery was determined from all microplots in plant tissue at flowering, in the grain, and straw at harvest and in the soil. Fertilizer N(15NH4 15NO3) was applied atratesof 0, 45, 90, and 135kg N ha‐1 in Experiment 222, and 0, 22, 45, 67, 90, and 112 kg N ha‐1 in Experiment 502. The ratio ofNO3 ‐to NH4 + in wheat forage at flowering was positively correlated with estimated plant N loss. Estimated plant N loss (total N uptake in wheat at flowering minus N uptake in the grain and straw at maturity) ranged from a net gain of 12 kg N ha‐1 to a loss of 42 kg N ha‐1, and losses increased with increasing N applied.  相似文献   

4.
施用辐照处理的污水污泥对作物产量和土壤氮的影响   总被引：1，自引：0，他引：1  
A field experiment was conducted to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied at rates of 0 (CK), 75, 150, 225 and 300 kg N ha-1 for wheat, and 0 (CK), 112.5, 225, 337.5 and 450 kg N ha-1 for rice, respectively. (NH4)2SO4 at a rate of 150 kg N ha-1 for wheat, and 225 kg N ha-1 for rice were added to the control treatments. Additionally, 20 kg 15N ha-1 in the form of (NH4)2SO4 was added to each treatment for wheat to study the effect of sewage sludge on chemical nitrogen fertilizer recovery. The results showed that the irradiation of sewage sludge by gamma ray at a dosage of 5 kGy increased crop yield by 11%~27% as compared to the non-irradiated treatments. Irradiation stimulated mineralization of organic nitrogen in the sludge and improved seedling growth. It was found that addition of irradiated sludge could reduce the leaching loss of chemical nitrogen fertilizer. Both irradiated and non-irradiated sewage sludge could increase the content of soil total nitrogen. Based on the preliminary results, it was concluded that irradiated sewage sludge could partly substitute for chemical nitrogen fertilizer in crop production.  相似文献   

5.
Abstract

Two concentration levels for each of two polymer gels (polyacrylate and vinyl alcohol acrylic acid) were incorporated with urea, ammonium sulfate [(NH4)2SO4], and potassium nitrate (KNO3) fertilizer solutions and used as nitrogen (N) carriers to fertilize lettuce grown in a greenhouse and field study. Of the initial 1290 mg N applied, gel treatments contained up to 70 mg N after 43 days. The vinyl alcohol polymers retained significantly larger quantities of NO3‐N from the (NH4)2SO4 and KNO3‐N sources than from the urea source. The N concentration in each gel treatment was an important factor and dependent on the polymer and fertilizer source. Both gels performed better when incorporated with (NH4)2SO4 and KNO3 than with urea.  相似文献   

6.
 The objective of this study was to determine the efficiency of two N fertilizers, (NH4)2SO4 and urea, for rice (Oryza sativa L.) and rye-grass (Lolium multiflorum L.) cultivated in an Ultisol of central Amazonia using 15N as a tracer. Rice was cultivated in the field, while rye-grass was grown in a phytotron. Fertilization with (NH4)2SO4 caused a 16% increase in the yield of rice grains and urea a 36% increase. In both crops total N uptake and N use efficiency of the fertilizers were higher for urea than for (NH4)2SO4. The low values for N derived from fertilizer showed that the fertilizers contributed little to the total N absorbed by the plants. The "priming effect" or positive added N interaction (ANI) between the fertilizer N and soil organic N was observed, especially with urea. Immobilization by soil microorganisms was greater in the presence of urea, while losses were always higher with the (NH4)2SO4 treatments. These losses were significant, and their reduction should allow more efficient use of this N fertilizer. It is possible that the N use efficiency was higher for urea due to a pH increase, caused by urea hydrolysis, which in turn may have favoured the activity of nitrifying bacteria in this extremely acid soil. Received: 6 April 1999  相似文献   

7.
Abstract

Three polymers (polyacrylate, vinyl‐alcohol, starch‐based) were evaluated for controlled‐release properties when expanded in urea, ammonium sulfate ((NH4)2SO4), and potassium nitrate (KNO3) solutions, at five nitrogen (N) concentrations (0,10,15, 20 g N/L, and saturation). The expansion capacity (mL solution absorbed/g dry polymer) of each polymer varied and was dependent on the type and concentration of fertilizer solution. On average, polymers incorporated with urea, (NH4)2SO4, and KNO3 fertilizer solutions had expansion capacities of 275, 24, and 30 mL/g, respectively. All three polymers reacted with ammonium ions in solution and resisted normal extraction procedures of ammonium with 2N KCl. To determine gel characteristics when applied to a soil medium, selected gel treatments were incubated in containers of loamy sand soil up to 28 days and then assessed for the quantity of gel recovered, N content, and N concentration. Although most gels released a large portion of N after only 7 days, some gels slowed diffusion better than the dry fertilizer controls up to 28 days.  相似文献   

8.
土壤水湿状况和肥料碳氮比对稻田肥料氮素转化的影响   总被引：2，自引：0，他引：2  
朱培立  黄东迈 《土壤学报》1986,23(3):251-261
本文应用15N示踪法,测定并探讨了土壤中三种水分状况及四种不同C/N值肥料对肥料氮素转化的影响,试验结果表明:土壤水分和肥料C/N值均对水稻产量有较大的影响,相比之下,土壤水分的影响似更大.水稻对肥料氮的吸收利用率,淹水栽植高于旱植,氮素固定在旱地条件下作用加强,淹水并有一定渗漏的土壤上肥料氮的损失最大,示踪结果说明从土壤渗漏液中淋失的氮素80%以上为土壤固有氮素,相对而言肥料氮的损失较低.试验还表明肥料中碳氮值与肥料氮的吸收利用率之间呈负相关,与肥料残留率呈正相关.此外,本试验还测定了土壤水湿状况和肥料碳氮值在土壤氮素转化中的作用,讨论了当土壤氮素矿化和固定作用相等时,有机肥的碳氮临界值及其实用意义.  相似文献   

9.
Five‐week‐old tomato plants were transplanted into pots containing 10 kg of potting compost which was amended with 0, 0.1, or 0.3 g of nitrapyrin and 4 g of N from KNO3, (NH4)2SO4 or sewage sludge and were grown in a greenhouse. After 2 to 3 weeks, leaves of the plants grown on any nitrapyrin x N source combination were curled with reduced laminae. Symptoms were most severe with the nitrapyrin x sludge regimes and least severe with the nitrapyrin x KNO3 treatments. With (NH4)2SO4 and sludge, growth was depressed linearly by nitrapyrin additions but was unaffected with KNO3 fertilization. The concentrations of Ca and Mg in the shoots were lowered linearly or curvilinearly by nitrapyrin combination with any fertilizer whereas that of K was unaffected. Levels of Mn in leaves rose with nitrapyrin additions to the (NH4)2SO4 or sludge treatment but were stable with any of the nitrapyrin x KNO3 combinations. Cation antagonism among NH4 +, Ca++, and Mg++ is suggested as affecting the concentrations of these ions in tissues, whereas acidification of the medium and a restriction in dry matter production may account for the elevated levels of Mn in the tomato shoots grown in the presence of nitrapyrin.  相似文献   

10.
Immobilization of N was measured in a fumigated and in an unfumigated soil by adding (15NH4)2SO4 and following the disappearance of inorganic label from the soil solution and its simultaneous conversion to soil organic N. Calculations based on the measurement of organically-bound 15N gave more consistent values for immobilization than did calculations based on the measurement of the disappearance of label from solution. The fumigated soil immobilized 6.6 μg N g?1 N g?1 soil in 10 days at 25°C, the unfumigated control 4.8 μg. The corresponding gross mineralization rates were 34.9 and 5.6 μg N g?1 soil in 10 days.Addition of 58 μg N as (15NH4)2SO4 to the fumigated soil increased the quantity of the ynlabelled NH4-N extracted at the end of 10 days from 33.8 to 37.8 μg Ng?1 soil, i.e. there was a positive Added Nitrogen Interaction (ANI). The added labelled N produced this ANI, not by increasing the rate of mineralization of organic N, but by standing proxy for unlabelled N that otherwise would have been immobilized.A procedure for calculating biomass N from the size of the flush of mineral N caused by fumigation is proposed. Biomass N (BN) is calculated from the relationship BN = F'N/0.68 where F'N is [(N in fumigated soil incubated for 10 days — (N in unfumigated soil incubated for 10 days)].  相似文献   

11.
Abstract

Laboratory incubation and greenhouse experiments were conducted with two soils having contrasting physico‐chemical characteristics to evaluate nitrogen (N) mineralization, immobilization in soil microbial biomass, and accumulation in Japanese mint (Mentha arvensis L.) using labeled (15NH4)2SO4, applied at 0, 50, and 100 mg#lbkg‐1 soil. Rate of mineralization in soils varied from 0.08 to 2.21 μg#lbg‐1#lbday‐1. Fertilizer application increased the mineralization of native soil N. About 22 to 60% of the applied 15N was recovered in the soil microbial biomass during the growth period of mint (January‐June). Relative contribution of fertilizer 15N towards total N uptake by mint at maturity was 42–54% in soil I and 35 to 55% in soil II. Contribution of soil N towards total N accumulation increased with the doses of 15N application.  相似文献   

12.
Abstract

The presidedress soil nitrate test (PSNT) and the presidedress tissue nitrogen test (PTNT) have been developed to assess residual soil nitrogen (N) sufficiency for corn (Zea mays L.) in the humid eastern U.S. We conducted field studies at 47 sites during 1990 and 1991 to evaluate the use of the PSNT and PTNT for corn in Coastal Plain, Piedmont, and Appalachian Ridge and Valley regions of Virginia. Seven rates of fertilizer N (0, 45, 90, 135, 180, 225, and 270 kg/ha) were applied at corn height of 0.40 to 0.50 m and replicated four times in a randomized complete block design. Whole corn plants and soil to a depth of 0.30 m were sampled when corn height was 0.15 to 0.30 m to estimate available soil N prior to the application of fertilizer N treatments. Corn grain yield response to fertilizer N was used to assess residual soil N availability. Nitrogen concentration of whole corn plants at 0.15 to 0.30 m height was not an accurate indicator of plant‐available soil N. Corn yields were maximized without sidedress N at the 19 sites where soil NO3‐N was at least 18 mg‐kg‐1 and at the 17 sites where soil (NO3+NH4)‐N was at least 22 mg‐kg‐1. The PSNT predicted corn N sufficiency regardless of soil physiographic region or surface texture; however, the critical values for NO3‐N and (NO3+NH4)‐N were 3 to 5 mg‐kg‐1 lower than those established in Pennsylvania and Maryland, where cooler soil temperatures may permit greater residence time of inorganic N.  相似文献   

13.
 The effects of applying either inorganic fertilizer or leaf mulch of Acacia saligna (Labill.) H.L. Wend. on yields of Sorghum bicolor (L.) were compared with an unfertilized control under the high leaching conditions of runoff irrigation in a dry tropical environment. The N use efficiency and transfer from 15N-labelled (NH4)2SO4 or acacia leaves to the sorghum differed in quantity and quality. Only 6% of the applied mulch N was retrieved in the crop, in contrast to 21% of the fertilizer N. The proportions of N in the crop derived from the fertilizers were small, amounting to 7% and 28%, respectively, in the mineral fertilizer and mulch treatments. However, the application of inorganic fertilizer and mulch significantly increased crop grain yield (P<0.05 and P<0.1, respectively), biomass production and foliar N contents (P<0.05). The inorganic fertilizer improved crop yields to a larger extent than mulching. At the same time, more N was lost by applying (NH4)2 SO4 than leaf mulch: only 37% of the N of applied (NH4)2 SO4 was found in the crop and the soil (0–0.3 m), but 99% of the mulched N. High NO3 – contents in the topsoil of the inorganic fertilized sorghum treatments indicated the risk of N leaching. However, more important may have been gaseous N losses of surface-applied NH4 +. From a nutrient conservation point of view, mulches should be given preferance to inorganic fertilizers under high soil pH and leaching conditions, but larger improvements of crop yields could be achieved with mineral fertilizers. Received: 29 July 1998  相似文献   

14.
Maximizing nitrogen use efficiency (NUE) involves synchronizing the interplay between nitrogen preferential crops and the nitrogen transformation pathways of soil. Biochar may benefit specific N-preference crops in relatively unsuitable soil environments; however, experimental data are lacking. This study tested eight treatments, consisting of four nitrogen treatments (N0 = control; N1 = NH4Cl; N2 = NaNO3; and N3 = 1:1 ratio of NH4+ and NO3−) each with biochar applied at 0% or 2% (w/w). The results show that biochar and/or nitrogen application enhanced maize seedling biomass and NO3−-based fertilizer resulted in higher seedling biomass than NH4+-based fertilizer. With the application of biochar and NH4+-based fertilizer, maize seedling biomass increased and soil NH4+-N content was significantly reduced compared with NH4Cl sole application. Correlation analysis and redundancy analysis revealed that SOC content and inorganic nitrogen content were the main factors influencing maize growth and N absorption. Biochar with or without nitrogen fertilizer (except N1 treatment) significantly increased β-1,4-glucosidase (BG) activity. Co-application treatments also resulted in higher vector length, an indicator of C limitation—the increment might add to the risk of microbial C limitation. The activity of ammonia monooxygenase (AMO), a key enzyme in nitrification, decreased with the co-application of biochar and nitrogen, suggesting the alteration of nitrogen transformation.  相似文献   

15.
盆栽试验以混合肥料的碳氮比值为指标基施等量硫铵(15N)和不等量稻秆,在同一盆内连续植稻三季,研究稻秆对15N硫铵氮素的去向和水稻生产的影响,以及被固定氮的残效。结果表明,稻秆显著地抑制硫铵的肥效及延缓水稻生长和发育的作用仅发生于植稻的第一季,并和混合肥料的碳氮比有关。对二、三季水稻氮的贡献很小,但高碳氮比处理能回收较多的硫铵氮素并取得较大的水稻反应。植稻三季后,硫铵混合和不混合稻秆处理的水稻生物产量间及稻穗中硫铵氮素的总和间(不含最高稻秆用量处理),均没有显著差异。 硫铵氮素的固定作用在第一季作物表现十分明显。残留土壤中的硫铵氮素颇为稳定,在连续植稻过程中不易释放出来被水稻吸收,尤其是在第三季。硫铵氮素的损失主要发生于植稻的第一和笫二季,稻秆对其固定具有防止硫铵氮素损失的作用。  相似文献   

16.
The method of fertilizer nitrogen (N) application can affect N uptake in tall fescue and therefore its yield and quality. Subsurface-banding (knife) of fertilizer maximizes fescue N uptake in the poorly-drained clay-pan soils of southeastern Kansas. This study was conducted to determine if knifed N results in greater N uptake than the conventional top-dress application method in a deep, well-drained soil of east-central Kansas. The experiment, conducted in a Smolan silty clay loam soil, was a split-plot with fertilizer nitrogen rates 0, 140 and 280 kg N ha?1 applied as urea-ammonium nitrate (UAN, 28% N), knifed or top-dressed. Soil inorganic N [ammonium (NH4)- and nitrate (NO3–N)] and N in roots and plant tops were measured at various times during the growing season. At final harvest, most of the knifed N (99.7%) was accounted for in plant tissue (roots and tops) and soil, with more than half of the knifed N remaining as soil inorganic N. With the top-dressed method, 27% was unaccounted for and presumed lost in gaseous form. Knifing fertilizer N in fescue fields of east-central Kansas will maximize the availability of N, reduce potential N losses, and increase forage quality.  相似文献   

17.
Abstract

In semi‐arid regions, soil depth influences soil N uptake, but not ferilizer N uptake. How soil depth interacts with soil and fertilzer N to influence N uptake in humid regions is not known. The objective was to determine the relative importance of soil depth and soil and fertilizer N uptake, by forage grasses. Tall fescue (Festuca arundinacea Schreb.) and switchgrass (Panicum virgatum L.) were grown on soils of varying depths. Nitrogen rates are 0, 90, and 180 kgN/ha of 15N depleted (NH4)SO4 applied in a split application on fescue and in one aplication to switchgrass. Total N and fertilizer N uptake, were regressed against fertilizer N, variables related to soil depth (waterholding capacity (WC), water use (WU), water loss (WL), and total soil N (SN). Soil variables explained 28% of the accoutable variation in total N uptake by first cut fescue but only 10% by second cut fescue. Soil variables explained 11% of the accountable variation in fertilizer N uptake by first cut fescue and none by the seoond. Soil variables explained 40% of the accountable variation in the total N uptake, by switchgrass, but only 10% of the variation in the fertilizer N uptake. Only where soil depth was less than 90 cm did it have a significant effect on the fertilizer N uptake by first cut fescue. Soil depth had no significant effect on the uptake, of fertilizer N by second cut fescue or switchgrass.  相似文献   

18.
A laboratory incubation experiment was conducted to study the effect of indigenous inorganic N on the immobilization of applied N and on the occurrence of an added N interaction (ANI). Samples of six Mollisols from Illinois were incubated with 15N-labelled (NH4)2SO4 (100 or 200 mg N kg-1 soil), with or without the use of 0.01 M CaCl2 to extract inorganic N (mainly NO inf3 sup- ) before incubation. From 6 to 49% of the N applied was immobilized, higher percentages being obtained with unextracted soils than with the extracted soils and with the higher rate of N addition. Net mineralization of native N occurred in both the unextracted and extracted soils, but was more extensive in the unextracted soil and increased with the addition of N. The increases were accompanied by a positive ANI, which usually exceeded the amount of applied N immobilized and increased with the rate of addition. The ANI values observed with extracted soils were attributed to increased mineralization of native organic N.  相似文献   

19.
Results are presented from a 3-year investigation into nitrate leaching from grassed monolith lysimeters treated with double (15NH415NO3) or single (15NH4NO3) labelled ammonium nitrate at three rates, 250, 500 and 900 kg N ha?1 a?1. Over the 3 years of the experiment, 0.14%, 3.1% and 18.1% of the applied fertilizer was recovered in the leachate at 250, 500 and 900kg N ha?1 respectively. This represented 9%, 39% and 75% of the overall nitrate leaching at the three application rates. A significant proportion of the fertilizer leached as nitrate at the three application rates was derived, via nitrification, from the fertilizer ammonium. Increasing fertilizer applications caused a rise in the leaching of both soil and fertilizer derived nitrogen, although whether the increase reflected a true priming effect was not clear.  相似文献   

20.
Displacement of NH4+ fixed in clay minerals by fertilizer 15NH4+ is seen as one mechanism of apparent added nitrogen interactions (ANI), which may cause errors in 15N tracer studies. Pot and incubation experiments were carried out for a study of displacement of fixed NH4+ by 15N‐labeled fertilizer (ammonium sulfate and urea). A typical ANI was observed when 15N‐labeled urea was applied to wheat grown on soils with different N reserves that resulted from their long‐term fertilization history: Plants took up more soil N when receiving fertilizer. Furthermore, an increased uptake of 15N‐labeled fertilizer, induced by increasing unlabeled soil nitrogen supply, was found. This ANI‐like effect was in the same order of magnitude as the observed ANI. All causes of apparent or real ANI can be excluded as explanation for this effect. Plant N uptake‐related processes beyond current concepts of ANI may be responsible. NH4+ fixation of fertilizer 15NH4+ in sterilized or non‐sterile, moist soil was immediate and strongly dependent on the rate of fertilizer added. But for the tested range of 20 to 160 mg 15NH4+‐N kg–1, the NH4+ fixation rate was low, accounting for only up to 1.3 % of fertilizer N added. For sterilized soil, no re‐mobilization of fixed 15NH4+ was observed, while in non‐sterile, biologically active soil, 50 % of the initially fixed 15NH4+ was released up to day 35. Re‐mobilization of 15NH4+ from the pool of fixed NH4+ started after complete nitrification of all extractable NH4+. Our results indicate that in most cases, experimental error from apparent ANI caused by displacement of fixed NH4+ in clay is unlikely. In addition to the low percentage of only 1.3 % of applied 15N, present in the pool of fixed NH4+ after 35 days, there were no indications for a real exchange (displacement) of fixed NH4+ by 15N.  相似文献   

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