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  • Cambridge University Press  (3)
  • 1960-1964
  • 1955-1959
  • 1940-1944  (3)
  • 1944  (1)
  • 1942  (2)
  • 1
    Publication Date: 1942-01-01
    Description: 1. Increasing the ballast on pneumatic tyres, up to a certain weight, improves the tractor performance as judged by its speed, fuel consumption and wheel slip. Further increases beyond this point continued to decrease the wheel slip without having any marked effect on its speed or fuel consumption. No certain evidence was obtained that too heavy a ballast decreased the tractor's efficiency.2. The tyre load affects the maximum pull the tractor can exert while working reasonably efficiently, but this pull does not depend markedly on the speed of work. Wheel weights of about 12–13 cwt. seem to be the minimum required for optimum performance of the 36 or 28 in. tyres at pulls of 1800 lb. under fairly good ground conditions, and possibly a greater weight may be required by the 24 in. tyre.3. If the tractor is ploughing it is usually running tilted, and this tilt transfers sufficient weight on to the furrow wheel for it to work efficiently under most conditions. Additional ballast is, however, often necessary for the lighter land-side wheel.4. Tyre performance is much less dependent on inflation pressure than on ballast. Pressures below 10 lb./sq. in. were only of use in wet conditions when small amounts of additional ballast were not available. Pressures above 12 lb./sq. in. may allow excessive slip to take place and probably only need be used on the furrow wheel of a well-loaded tractor ploughing.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 2
    Publication Date: 1944-07-01
    Description: A method is described for determining the field volume and the air space of a clod of any shape by filling its pores with a hydrocarbon oil, such as paraffin or tetralin, and determining its weight in the oil and in air before and after impregnation. The method appears to work well for clods of any moisture content.This method is shown to give values of these volumes entirely comparable with those given by the other accurate methods described in the literature. Its accuracy for clods of Rothamsted soil, weighing between 20 and 500 g., was probably at least 1 part per thousand, i.e. 0-1%.The method has been applied to the determination of the available water held by a soil and has been used to illustrate the effect of long-continued applications of farmyard manure to a soil in increasing the amount of available water it can hold.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
    Publication Date: 1942-07-01
    Description: Experiments on the effect of inter-row cultivation of sugar beet, carried out in the three years 1939–41 on a sandy loam, led to the following results:1. If the soil nutrients are in short supply hoeing or hand-weeding increases the yield of the beet, provided these operations are carried out before or shortly after singling.2. Hoeing is more effective than hand-weeding, but it cannot yet be said with certainty whether this is due entirely to more efficient weed destruction, or whether there is some additional effect, such as mulching.3. If adequate quantities of soil nutrients are present, inter-row cultivation has little effect on yield, and the crop can tolerate a considerable weed infestation without any effect on yield.The results for sugar beet on the heavy clay-with-flints soil at Rothamsted show:1. Additional hoeings after singling, above a modest minimum, have either no effect on yield or else depress it.2. On the one occasion when pre-singling cultivations were given, the yield was increased.3. In contrast with the Woburn results the effect of cultivation does not vary with, the level of manuring.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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