Improved method for automated determination of ammonium in soil extracts

Gentry, Claude E.; Willis, Raymond B.

doi:10.1080/00103628809367970

Cited by 48 publications

(22 citation statements)

References 24 publications

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“…P fractions were determined according to the method of Murphy and Riley (1962). The N fractions were determined colorimetrically following the methods of Gentry and Willis (1988), for NH 4 -N, and Kamphake et al (1967), for TON and TDN.…”

Section: Methodsmentioning

confidence: 99%

The composition of nutrient fluxes from contrasting UK river basins

et al. 1998

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Abstract:Accurate estimates of N and P loads were obtained for four contrasting UK river basins over a complete annual cycle. The fractionation of these loads into dissolved and particulate, and inorganic and organic components allowed a detailed examination of the nutrient load composition and of the factors in¯uencing both the relative and absolute magnitude of these components. The particulate phosphorus (TPP) loads account for 26±75% of the annual total phosphorus (TP) transport and are predominantly inorganic. The inorganic (PIP) and organic (POP) fractions of the TPP loads represent 20±47% and 6±28% of the annual TP transport, respectively. In contrast, the particulate nitrogen loads (TPN) represent 8% or less of the annual total nitrogen (TN) loads and are predominately organic. For dissolved P transport, the dissolved inorganic fraction (DIP) is more important, representing 15±70% of the TP loads, whereas the dissolved organic fraction (DOP) represents only 3±9% of the TP loads. The TN loads are dominated by the dissolved component and more particularly the total oxidized fraction (TON), which is composed of nitrate and nitrite and represents 76±82% of the annual TN transport. The remaining dissolved N species, ammonium (NH 4 -N) and organic N (DON) account for 0 . 3±1 . 2% and 13±16% of the annual TN transport, respectively. The TPN and TPP¯uxes closely re¯ect the suspended sediment dynamics of the study basins, which are in turn controlled by basin size and morphology. The dissolved inorganic nutrient¯uxes are in¯uenced by point source inputs to the study basins, especially for P, although the TON¯ux is primarily in¯uenced by diuse source contributions and the hydrological connectivity between the river and its catchment area. The dissolved organic fractions are closely related to the dissolved organic carbon (DOC) dynamics, which are in turn in¯uenced by land use and basin size. The magnitude of the NH 4 -N fraction was dependent on the proximity of the monitoring station to point source discharges, because of rapid nitri®cation within the water column. However, during storm events, desorption from suspended sediment may be temporarily important. Both the magnitude and relative contribution of the dierent nutrient fractions exhibit signi®cant seasonal variability in response to the hydrological regime, sediment mobilization, the degree of dilution of point source inputs and biological processes. #

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Section: Methodsmentioning

confidence: 99%

The composition of nutrient fluxes from contrasting UK river basins

et al. 1998

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“…The sampling depths were 0-15, 15-30 and 30-60 cm. Soil samples were analyzed for nitrate-N and sodium bicarbonate soluble P by methods of Gentry and Willis (1988) and Hamm et al (1970), respectively, (Table 1).…”

Section: Methodsmentioning

confidence: 99%

Forage seed yield response to N and P fertilizers and soil nutrients in northeastern Saskatchewan

Loeppky¹,

Horton²,

Bittman³

et al. 1999

Can. J. Soil. Sci.

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Forage seed yield response to N and P fertilizers and soil nutrients in northeastern Saskatchewan. Can. J. Soil Sci. 79: 265-271. There is no information on the effect, in northeastern Saskatchewan, of N and P fertilizers on forage seed production as influenced by these nutrients in the soil. Therefore, experiments were conducted at eight sites from 1988 to 1991 to determine the effect of N and P fertilizers and soil nutrients on seed yields of alfalfa (Medicago media Pers.), smooth bromegrass (Bromus inermis Leyss.), crested wheatgrass (Agropyron cristatum L.), intermediate wheatgrass (Agropyron intermedium [Host.] Beauv.) and timothy (Phleum pratense L.). Nitrogen fertilizer (urea) was applied on grasses annually at 0, 50, 100 and 150 kg N ha -1 in factorial combination with 0, 9 and 18 kg P ha -1 (monoammonium phosphate and triple superphosphate) and on alfalfa at 0 and 50 kg N ha -1 in combination with 0, 9, 18, 26 and 53 kg P ha -1 . Nitrogen significantly increased forage seed yields of all species except alfalfa. Phosphorus increased yields of forage seed for all crops except intermediate wheatgrass. The site, N, P and year and their interactions influenced seed yields. Seed yields ranged from a low of 0.29 t ha -1 for smooth bromegrass in 1990, a dry year, to a high of 1.24 t ha -1 in 1989 a cool, moist year. The yield response to N and P fertilizers was affected by available soil N and P. Relative to control, the percentage increase in grass seed yield from applied N and P fertilizers was highly related to the available soil N and P (R 2 = 0.93). The estimated smooth bromegrass seed yield response to 50N-9P kg ha -1 was 0.54 t ha -1 when the soil had intermediate amounts of available N and P (2 mg N ha -1 and 8 mg P ha -1 , 0-to 60-cm and 0-to 15-cm depths, respectively). On a soil that tested high in available N and P, there was no response to fertilizer. Regression equations were developed that can be used to estimate forage seed yield response of different species in relation to available soil nutrients. These results are useful for estimating the most economical return on fertilizer investment for forage seed production in Saskatchewan.Key words: Forage, seed, N, P, fertilizer, soil tests, correlation Loeppky, H. A., Horton, P. R., Bittman, S., Townley-Smith, L., Wright, T. et Nuttall, W. F. 1999. Effets de la fumure N et P et de la biodisponibilité de ces éléments dans le sol sur le rendement de semences fourragères dans le nord-est de la Saskatchewan. Can. J. Soil Sc. 79: 265-271. Dans le nord-est de la Saskatchewan, on ne dispose d'aucune information sur l'effet de la fumure N et P sur la production de semences fourragères en fonction des quantités disponibles de ces éléments dans le sol. Des expériences ont été conduites de 1988 à 1991 à 8 emplacements pour déterminer l'effet des engrais N et P, ainsi que des disponibilités de ces éléments dans le sol, sur le rendement semencier de la luzerne (Medicago media Pers.), du brome inerme (Bromus inermis Leyss.), de l'agropyre à crête (Agropyron crista...

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“…Soil ammonium-N, nitrate-N, sodium bicarbonate soluble-P and sulphate-S were analyzed according to procedures described in Nuttall (1985a). After 1986, soil tests for N and P were analyzed by the methods of Gentry and Willis (1988) and Hamm et al (1970). The extractions for soil N, however, were made with 1N K 2 SO 4 .…”

Section: Methodsmentioning

confidence: 99%

Uptake of N, P and S in fertilized pasture herbage and herbage yield response to fertilizer as affected by soil nutrients

McCartney¹,

Bittman²,

Horton³

et al. 1998

Can. J. Soil. Sci.

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1998. Uptake of N, P and S in fertilized pasture herbage and herbage yield response to fertilizer as affected by soil nutrients. Can. J. Soil Sci. 78: 241-247. Uptake of N, P and S nutrients in the herbage of different pasture species were determined at eight sites within pastures located on Luvisolic soils in northeastern Saskatchewan, Canada. Also, the nutrient status of the soil was related to herbage yield response to N, P and S fertilizers. Soil tests would be used to establish the initial response to ferilizer and thereafter, nutrients removed from the soil could be replaced by fertilizer. Experiments in the study included one site with bromegrass (Bromus inermis Leyss.) and alfalfa (Medicago media Pers.), six sites on a pasture mixture (Bromus inermis Leyss., Festuca rubra L., Poa pratensis L. and Medicago media Pers.) and one site with Russian wildrye (Psathyrostachys juncea (Fisch.) Nevski) at both Pathlow and Pleasantdale pastures. Nitrogen and P fertilizers were applied at 0, 45 and 90 kg N ha-1 in combination with P at 0 and 20 kg ha-1. Sulphur treatments included 90N-20P-2-S (sulphate source, kg S ha-1) on pasture mixture sites and two treatments of 90N-20P-23S and 90N-20P-45S (elemental source, kg S ha-1) on bromegrass and alfalfa. Maximum uptake of nutrients were 103.6 kg N, 11.5 kg P and 5.2 kg S ha-1 with the application of 90N-20P-45S (kg ha-1) on the bromegrass-alfalfa pasture. The controls resulted in the lowest uptake of 20.2 kg N, 1.9 kg P (pasture mixture) and 1.5 kg S ha-1 (bromegrass and alfalfa). Yield response to N and P fertilizers (percentage yield over control) was related to soil tests for N, P and S (r 2 = 0.42). Herbage yield increase (log 10 mean of years) from S fertilizer over the control was negatively related to the soil test for S on six sites (r 2 = 0.77). Uptake of N, P and S in herbage gave an adequate estimate of nutrient removal and the amount of fertilizer to apply to maintain soil nutrient levels.. 1998. Exportation de N, P et S par un pâturage fertilisé et réaction du rendement herbager à la fumure selon la teneur en éléments nutritifs du sol. Can. J. Soil Sci. 78: 241-247. Nous avons mesuré les exportations de N, P et S par diverses espèces de plantes de pâturage à 8 emplacements situés sur sols luvisoliques du nord-est de la Saskatchewan au Canada. En outre, nous avons confronté le niveau de fertilité du sol avec la réaction du rendement herbager aux fumures N, P et S. Des analyses de sol permettaient d'établir la réponse initiale à la fumure, de sorte que par après les éléments nutritifs exportés dans la culture pouvaient être remplacés par des engrais chimiques. Les expériences analysées ici comportaient un emplacement avec brome inerme (Bromus inermis Leyss) et luzerne (Medicago media Pers.), six emplacements utilisant une association à pâturage (B. inermis Leyss., Festuca rubra L., Poa pratensis L. et M. media Pers.) et un emplacement utilisant un peuplement d'élyme de Russie (Psathyrostachys juncea (Fisch.) Nevski) répartis entre deux localités Pathlow et Ple...

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Improved method for automated determination of ammonium in soil extracts

Cited by 48 publications

References 24 publications

The composition of nutrient fluxes from contrasting UK river basins

The composition of nutrient fluxes from contrasting UK river basins

Forage seed yield response to N and P fertilizers and soil nutrients in northeastern Saskatchewan

Uptake of N, P and S in fertilized pasture herbage and herbage yield response to fertilizer as affected by soil nutrients

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