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Nitrogen Efects on Crested Wheatgrass as Related to Forage Quality Indices of Grass Tetany

Mayland, H.F. and Grunes, D.L. and Waggoner, H. and Florence, A. and Hewes, D.A. and Joo, P.K. (1975) Nitrogen Efects on Crested Wheatgrass as Related to Forage Quality Indices of Grass Tetany. Agronomy Journal. 67(3):411-414.


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Nitrogen fertilization of forage is often accompanied by an increased incidence of grass tetany. A field experiment was established on two calcareous soils to evaluate the effects of N fertilizer on forage quality indices of grass tetany. Nitrogen, as NH?NO?, was applied at 0 and 150 kg N/ha in each of 2 years to separate plots. The crested wheatgrass [Agropyron desertorum (Fisch.) Schult] forage was harvested at regular intervals in the Spring tetany period during 1968 through 1971. Forage was analyzed for inorganic cations, N, total water-soluble carbohydrates (TWSC), aconitic acid, higher fatty acids (HFA), dry matter, and ash alkalinity — a measure of total organic acids. Nitrogen fertilizer increased the concentrations (equiv. basis) of forage Mg and Ca more than the increase in K, thus slightly reducing the K/(Ca + Mg) values when compared to the unfertilized forage. However, forage K/(Ca + Mg) values were usually less than the 2.2 value above which the incidence of grass tetany increases rapidly. The potential dietary benefits from the higher Mg concentrations may have been offset by increased concentrations of K, N, HFA, N/TWSC, and aconitic acid, since these parameters are associated with decreased Mg availability to cattle. Low values for hypothetical blood serum Mg (calculated from forage N, Mg, and K concentrations) coincided with the occurrence of grass tetany in the field. The calculated serum Mg values were lower in the N-fertilized forage than in the control. The aforementioned effects of N fertilization should not deter the judicious use of N for optimizing forage yields on semiarid ranges, since other research workers have found that grass tetany losses can be reduced by supplementing animals with Mg.

Item Type: Article
NWISRL Publication Number: 0328
Subjects: Irrigated crops > Grass forage > Chemistry
Irrigated crops > Grass forage > Forage quality
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:51
Last Modified: 15 Feb 2017 21:13
Item ID: 285

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