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1.
The distribution and recovery of urea N (25 kg ha–1) applied in solution by low-flow furrow irrigation to wheat, direct-drilled in rows in 1.5m wide permanent beds of a red-brown earth, was determined using15N labelled fertilizer. This method of fertilizer application resulted in an uneven distribution of applied N across the soil bed. Fertilizer N was recovered mainly in the upper 0.15m horizon of the soil. Forty seven percent of the applied N was recovered in the soil and plants within 0.20m of the point of application. Recovery rapidly decreased with increasing distance from the furrow and less than 4% of the urea N was recovered by the plants in the fourth row, 0.67m from the middle of the furrow. The recovery of fertilizer N in the crop was 23, 28, 47 and 40% at 13, 32, 59 and 86 days, respectively; the corresponding total recovery in the crop plus soil was 77, 91, 87 and 75%; the mean being 83 ± 8%.The results suggest that with this method of fertilizer application and these soil properties the furrows should be less than 0.75m apart in order to get uniform distribution of the fertilizer.  相似文献   

2.
控释尿素对小麦增产效果与提高氮肥利用率的研究   总被引:2,自引:1,他引:2  
采用控释尿素和普通尿素两种氮素肥料进行优质小麦郑麦366肥效试验研究。两地试验结果表明:100%控释尿素处理产量最高,为7980kg/hm^2和8290kg/hm^2,与同等氮素用量的普通尿素相比增产12.0%、14.0%;产量随氮肥用量的增加而增加;用量70%控释尿素处理与用量100%普通尿素处理之间相比,产量差异不大,没有达到显著性差异,说明施用控释尿素可以比普通尿素减少1/3的纯氮用量。  相似文献   

3.
The objective of this study was to increase the efficiency of fall-applied N either by placement in bands or by using a slow-release fertilizer. Four field experiments were conducted in north-central Alberta to determine the influence of N source, time of application and method of placement on the recovery of fall-applied N as soil mineral N in May, and on yield and recovery of N in grain of spring-sown barley. The recovery in soil of mineral N by May from the fall-applied fertilizers varied among treatments. More specifically, the recovery was lowest with topdressed application, highest with banding, and tended to be less with incorporation application as compared to banding. Recovery of mineral N was least for sulphur-coated urea (SCU) compared with A.N. and urea, regardless of method of application. The loss of fall-applied N was substantial, but leaching did not go beyond 60 cm deep.Yield and recovery of N in barley grain were much greater with spring application than with fall application at the 4 sites for ammonium nitrate (A.N.) and at 3 sites for urea. The SCU treatments were inferior. The A.N. and urea had greatest yield and N recovery with banding, followed by incorporation and then with topdressing for both fall- and spring-applied N. Method of application had little effect on yield and N uptake with SCU. In all, the greatest yield or crop N uptake was obtained with spring banding of A.N. or urea, while SCU did not function well as a fall- or spring-applied N fertilizer.(Contribution No. 680)  相似文献   

4.
The potential for improved fertilizer N use efficiency was tested using a slow release N fertilizer, methylene urea (MU), on processing tomato (Lycopersicon esculentum Mill.) in a 2-year field study in the Sacramento Valley, California. Fertilizer N use efficiency of urea and a (50:50, w:w) mixture of urea and MU (uMU) was determined in direct-seeded and transplanted tomato plots with winter cover crop (CC) or winter fallow (F) using 15N labeled fertilizers. Residual MU-N was estimated from tomato N uptake in the 15N microplots, and from residual 15N uptake of wheat grown after two tomato crops. No significant differences were found in the quantity and quality of tomato yields among fertilizer and management treatments during the first year. Total yields in transplanted FuMU plots were significantly lower in the second test year, suggesting slow mineralization of MU-N in the F treatment. On average, about 40% of added fertilizer N was taken up in both fertilizer treatments, and the recovery of 15N in plant biomass and soil was 75–96 and 50–74% in seeded and transplanted blocks, respectively. In the laboratory, mineralization of MU started faster in soils with past MU use, but the enhanced mineralization did not affect the plant N uptake in the field. MU is potentially an environmentally attractive fertilizer, but without an immediate increase in yield and N use efficiency compared to conventional fertilizers, its use on row crops may not be economically feasible unless the positive environmental factors like decreased leaching of N are considered.  相似文献   

5.
In a laboratory experiment 5 cm depth of water was allowed to percolate daily down through a 15 cm thick soil (Typic Ustipsamment) layer. It was observed that leaching losses of urea supergranules (USG)-N could be decreased by about 20% by the placement of four 0.25 g granules at four points instead of one 1 g granule at one point. In field microplots, the placement of approximately 30 granules of 0.30 g size instead of 9 granules of 1.00 g size resulted in reduced leaching of USG-N and, in turn, increased rice yield. In a follow-up field study, the advantage of more frequently placed USG was confirmed. As compared with 1 g USG placed in the usual manner in the center of four rice hills, increasing the density of placement in soil produced 15% more rice grain. Further increase in rice yield could be obtained by increasing the number of USG placed in the soil and decreasing the size of the granule from 1.00 g to 0.70 or 0.35 g. With USG of 0.35 and 0.70 g yields were equal or sometimes even slightly higher than with split application of prilled urea on a heavily percolating, low-CEC, light-textured soil.  相似文献   

6.
A field study was conducted on a sandy clay soil (Entisol) in India to examine urea briquettes (UB) for lowland rice during 1986 and 1987. Grain yield was significantly greater for UB than a split application of prilled urea. At equal rates of N application, a spacing of 30 cm between two UBs was significantly better than 60 to 90 cm spacing. Two applications (10 DAT and at panicle initiation) of UB was no better than a single application (10 DAT). Placement of UB at 3–4 cm depth was significantly better than its surface application or placement at 0–1 cm depth.  相似文献   

7.
Fertilizer N losses on waterlogged texture-contrast soils (sand over clay) are usually attributed to denitrification and leaching. In this experiment, waterlogging events were imposed on 25-cm-diameter, 75-cm-long columns of texture-contrast soil planted to wheat (Triticum aestivum L.). Treatments included 6, 12, and 18 d of aerobic conditions between fertilization using 15N-labelled urea (5.0 g m-2) and 3-d waterlogging events. Denitrification, measured by 15N-chamber methods, was the largest loss mechanism identified during waterlogging. Dinitrogen was the main product of denitrification. Longer aerobic periods prior to waterlogging increased denitrification losses from 3.1 to 9.4% of the urea-N added. Leaching losses of 15NO3 (3.1 – 5.3%) between 20 and 70 cm were less than denitrification fluxes. Total15 N recovery in the wheat plants and soil was 87.9% before waterlogging and decreased to 72.3% after waterlogging. The balance of added fertilizer N was reasonably well reconstructed if it is assumed that NH3 volatilization accounted for the early loss of 12% of the urea-N, and that in addition to the measured surface fluxes of N2 + N2O, some of these gases remained entrapped in the soil. This study confirms that texture-contrast soils cropped to wheat have a high potential for N losses through denitrification and leaching during waterlogging events.  相似文献   

8.
Microplot experiments were conducted at two locations (Lacombe and Eckville) in central Alberta to evaluate methods of application of urea (60 kg N ha–1) on established meadow bromegrass (Bromus biebersteinii L. cv Regar). Urea was surface broadcast and banded 4 cm deep into soil at four row-spacings (15, 22.5, 30 and 37.5 cm). The dry matter and crude protein yield were generally greatest in plots when urea was banded at 15 cm spacing. There was a general decrease in dry matter yield, particularly with the first cut at the Lacombe site when urea was banded at more than 15 cm spacing. The dry matter yield, crude protein yield and crude protein concentration were significantly greater in grass adjacent to the banded fertilizer than in grass from the area midway between the bands at the Lacombe site.  相似文献   

9.
Rice is a very responsive crop to nitrogen, but the efficiency of the N-fertilizer is low. Greenhouse experiment has been conducted to evaluate several methods to improve fertilizer efficiency and reduce N-losses in rice fields. N-15 labelled urea was applied to 10 kg soils in pots, urea was applied alone, addition of two urease inhibitors N-(n-butyle) thiosphosphoric triamide (NBPT) and hydroquinone (HQ), with addition of nitrification inhibitor Dicyandimide (DCD), or with the combination of both inhibitors. The fertilizer was applied either broadcast on soil surface or at depth of 8 cm below the surface. At maturity, plants were separated into grain and straw, dried and weighted. Soil and plant samples were analyzed for total N and N-15 excess. Both fertilizer placement and inhibitor application significantly increased straw and grain yield, as well as N- uptake. Nitrogen derived from fertilizer (% Ndff) was more than doubled, when urea was applied deep and in combination with inhibitors. Total plant recovery of N-15 labelled urea ranged from 17% to 75% according to treatment. Regardless of inhibitors application, plant recovery was increased from 39% to 65% when urea was applied at depth of 8 cm. Approximately, 2/3 of the applied urea (64%) was lost, when urea was applied alone. Those losses were reduced down to 12% with deep placement and inhibitor application. The two management practices show significant effect on minimizing N-losses and increasing plant recovery.  相似文献   

10.
Recent research on problems in the use of urea as a nitrogen fertilizer   总被引:3,自引:0,他引:3  
Recent research on the NH3 volatilization, NO 2 - accumulation, and phytotoxicity problems encountered in the use of urea fertilizer is reviewed. This research has shown that the adverse effects of urea fertilizers on seed germination and seedling growth in soil are due to NH3 produced through hydrolysis of urea by soil urease and can be eliminated by addition of a urease inhibitor to these fertilizers. It also has shown that the leaf burn commonly observed after foliar fertilization of soybean with urea results from accumulation of toxic amounts of urea in soybean leaves rather than formation of toxic amounts of NH3 through hydrolysis of urea by leaf urease. It further showed that this leaf burn is accordingly increased rather than decreased by addition of a urease inhibitor to the urea fertilizer applied. N-(n-butyl)thiophosphoric triamide (NBPT) is the most effective compound currently available for retarding hydrolysis of urea fertilizer in soil, decreasing NH3 volatilization and NO 2 - accumulation in soils treated with urea, and eliminating the adverse effects of urea fertilizer on seed germination and seedling growth in soil. NBPT is a poor inhibitor of plant or microbial urease, but it decomposes quite rapidly in soil with formation of its oxon analog N-(n-butyl) phosphoric triamide, which is a potent inhibitor of urease activity. It is not as effective as phenylphosphorodiamidate (PPD) for retarding urea hydrolysis and ammonia volatilization in soils under waterlogged conditions, presumably because these conditions retard formation of its oxon analog. PPD is a potent inhibitor of urease activity but it decomposes quite rapidly in soils with formation of phenol, which is a relatively weak inhibitor of urease activity. Recent studies of the effects of pesticides on transformations of urea N in soil indicate that fungicides have greater potential than herbicides or insecticides for retarding hydrolysis of urea and nitrification of urea N in soil.  相似文献   

11.
Melamine (2,4,6-triamino-1,3,5-triazine) and ammeline (4,6-diamino-1,3,5 triazine 2(1H)-one) were tested in a field study for N release characteristics, and response of Kentucky bluegrass to one and two applications of 98 kg N ha–1. Melamine was also evaluated in combination with urea in a granule and in a liquid suspension. Mineralization of N from melamine and ammeline was slow. Soil concentrations of NH4 and NO3 in the surface 7-cm were less than 5% of the total N applied after 56 days. Recovery of N in the tissue was 5 and 11% of added melamine-N and ammeline-N respectively, during four months of sampling. Poor overall turf quality and number of dates of unacceptable quality also reflected the low mineralization of N from melamine and ammeline. The addition of urea to melamine improved plant N uptake, yield and turf quality. However, after the initial response to the urea component, little evidence of N release from melamine was observed over a four month period.Paper No.10 597 of the Journal Series of the Purdue Experiment Station, W. Lafayette, IN 47907.  相似文献   

12.
Conventional as well as modified nitrogen sources and application methods were evaluated under rainfed lowland conditions in heavy clay soils of Bihar, India for 4 years. Modified nitrogen sources, viz. sulfur-coated urea (SCU) and urea super-granules (USG) were tested against prilled urea (PU) under four levels of N (0, 29, 58 and 87 kg N/ha) in the wet season. A high yielding nonphotoperiod sensitive, long duration variety Pankaj was grown in all the four years.Point placement of USG and basal incorporation of SCU resulted in significantly higher panicle numbers per square meter, 100 grain weight and grain yield at all the levels of N tested. The unfilled grain percentage was lower in USG and SCU treatments.Regression analysis using a multifertilizer response model (MRM) showed that rice responded significantly to PU in three years out of four years, to SCU in four years and USG in three years.Economic analysis viz. input and output analysis based on the price of fertilizer (1 kg N as PU at $0.5; USG and SCU costing 10% more than PU), rough rice (ranging from 18.0 to 20.0 $ per ton) and labour wages at 1.0 $ per man day unit, also showed that USG and SCU are more input efficient than PU.  相似文献   

13.
Initial and residual effects of nitrogen (N) fertilizers on grain yield of a maize/bean intercrop grown on a deep, well-drained Humic Nitosol (66% clay, 3% organic carbon) were evaluated. Enriched (15N) N fertilizer was used to study the fate of applied N in two seasons: using urea (banded) at 50 kg N ha–1 in one season, and15N-enriched urea (banded), calcium ammonium nitrate (CAN, banded), and urea supergranules (USG, point placement) were applied in the other season (different field) at 100 kg N ha–1. Nitrogen fertilizer significantly (P = 0.05) increased equivalent maize grain yield in each season of application with no significant differences between N sources, i.e., urea, CAN, and USG. Profitmaximizing rates ranged from 75 to 97 kg N ha–1 and value: cost ratios ranged from 3.0 to 4.8. Urea gave the highest value: cost ratio in each season. Most (lowest measurement 81%) of the applied N was accounted for by analyzing the soil (to 150 cm depth) and plant material. Measurements for urea, CAN, and USG were not significantly different. The high N measurements suggest low losses of applied N fertilizer under the conditions of the study. Maize plant recovery ranged from 35 to 55%; most of this N (51–65%) was in the grain. Bean plant recovery ranged from 8 to 20%. About 34–43% of the applied N fertilizer remained in the soil, and most of it (about 70%) was within the top soil layer (0–30 cm). However, there were no significant equivalent maize grain increases in seasons following N application indicating no beneficial residual effect of the applied fertilizers.  相似文献   

14.
Poultry manure applied alone or in combination with urea at different N levels was evaluated as a N source for wetland rice grown in a Fatehpur loamy sand soil. Residual effects were studied on wheat which followed rice every year during the three cropping cycles. In the first year, poultry manure did not perform better than urea but by the third year, when applied in quantities sufficient to supply 120 and 180 kg N ha–1, it produced significantly more rice grain yield than the same rates of N as urea. Poultry manure sustained the grain yield of rice during the three years while the yield decreased with urea. Apparent N recovery by rice decreased from 45 to 28% during 1987 to 1989 in the case of urea, but it remained almost the same (35, 33 and 37%) for poultry manure. Thus, urea N values of poultry manure calculated from yield or N uptake data following two different approaches averaged 80, 112 and 127% in 1987, 1988 and 1989, respectively. Poultry manure and urea applied in 1:1 ratio on N basis produced yields in between the yields from the two sources applied alone. After three cycles of rice-wheat rotation, the organic matter in the soil increased with the amount of manure applied to a plot. Olsen available P increased in soils amended with poultry manure. A residual effect of poultry manure applied to rice to supply 120 or 180 kg N ha–1 was observed in the wheat which followed rice and it was equivalent to 40 kg N ha–1 plus some P applied directly to wheat.  相似文献   

15.
Phosphoroamide urease inhibitors were evaluated for their ability to increase grain protein and yield of winter wheat (Triticum aestivum L.) when added to surfaceapplied urea-based fertilizers. Six urease inhibitors [trichloroethyl phosphorodiamidate, diethyl phosphoric triamide, dimethyl phosphoric triamide, N-(diaminophosphinyl)-cyclohexylamine, N-benzyl-N-methyl phosphoric triamide, and phenylphosphorodiamide] were evaluated. Nitrogen treatments were urea prills, urea solution, and ureaammonium nitrate (UAN) solution broadcast and UAN solution band applied. Ammonium sulfate and no N treatments were included as controls. Fertilizer treatments were applied in the fall and spring. Soils were Ryker silt loam (Typic Paleudalf), Rensselaer loam (Typic Argiaquoll), and Avonburg silt loam (Aeric Fragiaqualf).Grain yield was a more responsive indicator of N addition than was grain N content. Urea prills and ammonium sulfate were more effective fertilizers than was UAN solution. UAN was not more effective applied in a band than broadcast. Urease inhibitors did not improve the efficiency of urea fertilizers since NH3 volatilization did not appear to be a problem following addition of urea fertilizers in spring or fall.Journal Paper No. 10528. This work was supported in part by a grant from Allied Chemical, Solvay, NY 13209.  相似文献   

16.
Labelled Ca(H2PO4)2 · H2O was added to two soils (an Oxisol and a vertisol) at two rates, both as a point source and completely dispersed through the soil. The point source treatments included two spatial distributions at each of two percentages of soil volume fertilized. Total and fertilizer phosphorus uptake by wheat (Triticum aestivum) grown for 42 days were determined in a glasshouse experiment. Uptake of fertilizer phosphorus was not affected by spatial distribution, but declined in the Oxisol as percentage soil volume fertilized increased at the low application rate. The implications of these results in terms of the effects of cultivation on fertilizer availability are briefly discussed.  相似文献   

17.
The effectiveness of wax coated calcium carbide to provide a slow release of acetylene to inhibit nitrification and denitrification in soil was evaluated in a field experiment with irrigated wheat (cv. Condor) grown on a red brown earth in the Goulburn-Murray Irrigation Region. The effect of the inhibitor treatments on biomass and grain yield was determined in 25 m × 3 m plots, and the effect on recovery, in the plant-soil system, of urea-N applied at sowing was determined in 0.3 m × 0.3 m microplots using a15N balance technique. The inhibitor limited ammonium oxidation, prevented nitrogen loss by denitrification for 75 days, increased N accumulation by the wheat plants, increased grain N and resulted in a 46% greater recovery of applied nitrogen in the plant-soil system at harvest. However, the inhibitor treatment did not increase grain yield because of waterlogging at the end of tillering and during stem elongation.  相似文献   

18.
Experiments were conducted to monitor the movement and distribution of ammonium-N after placement of urea and ammonium sulfate supergranules at 5, 7.5, 10, and 15 cm. By varying depths of fertilizer placement, it is possible to determine the appropriate depth for placement machines. There were no significant differences in grain yields with nitrogen placed 5 and 15 cm deep. However, grain yields were significantly higher with deep placement of nitrogen than with split application of the fertilizer. The lower yields with split-applied nitrogen were due to higher nitrogen losses from the floodwater. The floodwater with split application had 78–98µg N ml–1 and that with deep-placed nitrogen had a negligible nitrogen concentration.Movement of NH 4 + -N in the soil was traced for various depths after fertilizer nitrogen application. The general movement after deep-placement of the ammonium sulfate supergranules was downward > lateral > upward from the placement site. Downward movement was prevalent in the dry season: fertilizer placed at 5–7.5 cm produced a peak of NH 4 + -N concentration at 8–12 cm soil depth; with placement at 15 cm, the fertilizer moved to 12–20 cm soil depth. Fertilizer placed at 10 cm tended to be stable. In the wet season, deep-placed N fertilizer was fairly stable and downward movement was minimal.A substantially greater percentage of plant N was derived from15N-depleted fertilizer when deep-placed in the reduced soil layer than that applied in split doses. The percent N recovery with different placement depths, however, did not vary from each other. The results suggest that nitrogen placement at a 5-cm soil depth is adequate for high rice yields in a clayey soil with good water control. In farmers' fields where soil and water conditions are often less than ideal, however, it is desirable to place nitrogen fertilizer at greater depths and minimize NH 4 + -N concentration in floodwater.  相似文献   

19.
Five pot experiments were conducted with wheat and rice in a net house to study the effect of lime nitrogen (LN, contains about 55% calcium cyanamide) amendment rates on the efficiency of urea, the recovery urea-15N, the efficiency of the three nitrogen fertilizers(NF), on the efficiency of urea in the three soils, and on NO 3 - -N leaching from a flooded soil. A rate of LN-N of 5–8% of applied fertilizer N increased the recovery of labeled urea-N by 9.42%. The effect of LN on the efficiency of NF was urea > ammonium sulfate > ammonium chloride. Under flooded conditions, LN decreased NO 3 - formation and leaching.Responses of several crops to LN amended fertilizers were also studied in field experiments. At equal NPK applications, the efficiency of basal applications to rice, wheat, corn, potatoes, soybean, peanut, grapes, peaches, melon and watermelon were bette r with LN than without. Efficiency with a basal fertilizer for rice or wheat with LN were the same as with the same fertilizer without LN applied in split applications.  相似文献   

20.
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