Preparation and Properties of Urea-Form

Clark, K. G.; Yee, Jet; Love, Katharine S.; Boyd, T. A.

doi:10.1021/ie50496a031

Cited by 15 publications

(7 citation statements)

References 3 publications

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“…In recent years urea-formaldehyde reaction products (urea-form) have been manufactured (3) and used as fertilizers. Materials with a urea-formaldehyde ratio greater than I have N contents in excess of 37%, reduced solubilities in water and organic solvents,.…”

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“…Materials with a urea-formaldehyde ratio greater than I have N contents in excess of 37%, reduced solubilities in water and organic solvents,. and lower rates of nitrification in soil than do ammonium and nitrate forms of N fertilizers (3,4). Greenhouse studies (1) with grasses have shown that N in ureaform materials becomes available to the crop more slowly and more uniformly throughout the plant growth than that in conventional N fertilizer.…”

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Influence of Nitrogen Source and Rate on Growth of Spring Grain and Soil pH¹

Alessi¹,

Powers²

1972

Agronomy Journal

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The effect of five N sources upon spring grain production was studied on Temvik silt loam for 4 years at Mandan, N. Dak., and residual responses were followed for 4 more years. The five sources—ammonium nitrate, ammonium sulfate, calcium nitrate, Uramite, and Nitroform (urea‐formaldehyde)—were applied at rates of 0, 34, and 68 kg N/ha to spring wheat (Triticum aestivum) or barley (Hordeum vulgare L.). Results suggest that neither the rates of fertilization studied nor the interaction of N carrier × N rate were important in the production of total plant dry weight or grain yield. Small grain production was significantly altered by N source in only one of the fertilization years. Cumulative grain yields for 1960‐1963 were significantly increased by fertilization with nitrate and ammonium sources. Grain yields for the 8‐year period were significantly higher for ammonium and nitrate sources than for urea‐formaldehyde sources. Residual effects from urea‐formaldehyde fertilization were less effective for grain production than residual effects from nitrate and ammonium N carriers. Although ammonium sulphate lowered pH during the fertilization period, grain development was not seriously affected by this acidification. Cumulative grain production for the 8 years was 10,000 kg/ha with no N, 12,470 kg/ha with nitrate ammonium carriers, and 11,530 kg/ha with urea‐formaldehyde sources.

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Influence of Nitrogen Source and Rate on Growth of Spring Grain and Soil pH¹

Alessi¹,

Powers²

1972

Agronomy Journal

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“…Thus to match the two theories requires a precise knowledge of higher dimensional couplings in the five dimensional model. Furthermore, for modestly sized compact dimensions, ΛR ∼ 1−10, these "threshold" corrections to the four dimensional coupling constants maybe comparable in magnitude to the original coupling constants [10]- [13].…”

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Twisted Boundary Conditions and Matching to the Effective Four-Dimensional Theory

Clark

Love

2000

Mod. Phys. Lett. A

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Nontrivial twisted boundary conditions associated with extra compact dimensions can produce an ambiguity in the value of the four-dimensional coupling constants of the renormalizable interactions of the twisted fields' zero-modes. Resolving this indeterminacy would require a knowledge of the exact form of the higher-dimensional action including the coefficients of higher-dimensional operators. For the case of moderately sized extra dimensions, the uncertainty in the coupling constants can be of order one and may lead to modifications in the stability of the model.Theories with extra compact dimensions require that boundary conditions be specified on the fields that depend on the bulk coordinates. 1-6 When viewed as an effective four-dimensional field theory, the boundary conditions are reflected via an explicit phase dependence on the compact coordinates in the Fourier expansion coefficients of the fields. For the case of periodic boundary conditions, the coordinate derivative terms associated with the compact dimensions in the higher dimension Lagrangian get replaced in the four-dimensional Lagrangian by a corresponding Kaluza-Klein (KK) mass factor which varies as an integer multiple of the inverse compactification radius for each of the nonzero modes in the Fourier expansion. When the boundary conditions involve field periodicity up to a nontrivial global symmetry transformation phase (the nonzero twisting parameter), then there is an additional contribution to the mass arising from the coordinate derivative terms associated with the compact dimensions which again varies as the inverse compactification radius but also explicitly depends on the twisting parameter and holds for all the fields in the Fourier expansion including the zero-mode fields. Indeed, by imposing periodic boundary conditions up to a R-transformation, Scherk and Schwarz provided a mechanism to break supersymmetry in four dimensions through dimensional compactification. [7][8][9] In general, for order unity values of the twisting parameter, the masses of a zeromode field and its higher KK tower modes are of comparable magnitude. In such *

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“…THE GENERIC TERM "UREA-FORM" has been applied to urea-formaldehyde fertilizer materials. Such products have been described as mixtures of polymethyleneureas (5,6) which exhibit urea-formaldehyde mole ratios greater than 1, U/F > 1, nitrogen contents in excess of 37%, low solubilities in water and organic solvents, and lower rates of nitrification in soil media than the more soluble forms of chemical nitrogen fertilizers. The present paper reports the composition and solubility and nitri-fication characteristics of a wide variety of urea-formaldehyde reaction products in relation to their suitability for fertilizer use.…”

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confidence: 99%