Drying herbage

Wet oxidation of dried herbage, blood, meat, custard powder or other cellulose/protein low fat materials... 

M22. Mills, C. F., Availability of copper in freeze-dried herbage and herbage extracts to copper-deficient rats. BrU. J. Nutr. 9, 398-409 (1955). 

Concentrations of trace elements in oven-dry herbage from sludge-treated and untreated plots (ppm)... 

Curll, ci al. (1985) measured an increase in total yield from 6 t dry matter per ha with 10% white clover in the dry matter up to 11 t dry matter per ha with 45% white clover (Fig. 2.4). The increase in total yield was mainly caused by the increase in clover yield the grass yield remained more or less static, with clover levels above 20%. Reports from other experiments show considerable variation in the response. For this reason it can be stated only that white clover increases total herbage yield, but not at very high levels of clover, and that white clover always improves milk yield and liveweight gain compared with grass alone. 

The first indications of interaction between copper and molybdenum came more than 40 years ago from studies of grazing cattle in certain areas of England. Afflicted animals lost weight, developed severe diarrhea, and (in extreme cases) died. The disease is sometimes called teart (rhymes with heart) or molybdenosis, and is caused by eating herbage rich in molybdenum (i.e., 20 to 100 mg/kg dry weight diet compared to <5 mg/kg in nearby healthy pastures) and low or deficient in copper and inorganic sulfate (Underwood 1979). Molybdenosis is a copper deficiency... 

Another method used for nitrate determination on dried and milled herbage employs the nitrate selective electrode. One of the first published methods was that of Paul and Carlson (1968). Other anions, especially chloride, can interfere. These authors removed chloride with silver resin, but Barker ef al. (1971) omitted the resin because it tended to foul the electrode and cause excessive drift. Normally the Cl N03 ratio is so low as not to interfere, but saline precipitation from coastal plots could affect this. The method was further modified to allow storage of extracts for up to 64 h by adding a preservative of phenyl-mercuric acetate and dioxane, both very toxic (Baker and Smith, 1969). This paper mentions the need to change the electrode s membrane, filling solution and liquid ion exchanger every 2 months to minimize chloride interference. It is easy to overlook electrode maintenance between batches of nitrate analyses, and this can lead to errors and sluggish performance. 

If the analysis is to be carried out in a similar way to total N in herbage, by acid-digestion in test tubes in an aluminium block followed by a colorimetric autoanaiysis procedure, then take a 0.5-g sample of air-dry soil. If serious frothing occurs, take 0.2 g soil, and adjust the calculation accordingly. Reducing the amount to 0.1 g may give peaks which are too small to be read with confidence. See Chapter 7 (pp. 138-141) for details of standards, reagents and method. 

Jones, D.I.H. and Hayward, M.V. (1975) The effect of pepsin pre-treatment of herbage on the prediction of dry matter digestibility from solubility in fungal cellulase solutions. Journal of the Science of Food and Agriculture 26, 711-718. 

In this method, the herbage is first dried at 50 °C for 48 hours and milled to pass though a 0.5 mm screen. Ground material (1 g) is combined with magnesium nitrate solution, which acts as an ashing acid, and the mixture is ignited at 200 °C for 30 minutes and then at 450 °C for 5 -15 hours. The ignited residue is treated with potassium iodide and then dissolved in concentrated hydrochloric... 

Whether fallout is by washout or dry deposition, a certain fraction of the deposited activity is intercepted by foliage. Foliar deposition, followed by uptake by grazing animals, is an important pathway into food chains. The leaf area of herbage eaten by cattle and sheep is large. Also, animals eat herbage as it is, whereas humans usually wash leaf vegetables and discard outer leaves, pods and husks. 

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