Soil Science Volume 4

Soil Science Volume 4

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: on the graduated osmometer (about 2 feet away and about 4 inches below the surface) is indicated by the general decrease in water intake between periods 13 and 32. Unfortunately the rain began so soon after the osmometer was placed in position that conclusions regarding the apparent increase in water intake are not justified, for, as will be explained in section 3, the first few observations on the rates in each test are unreliable. Although in all cases the general decrease in the rates of water intake as time proceeds are very closely paralleled (with the exception noted above) by the slope of the calculated curve, it is conceivable that the conditions controlling the decrease in rates are wholly different from those considered in formulating the expression by which the calculated curve was obtained. That results calculated with the aid of an equation agree with experimental data is not conclusive evidence that the equation is based upon sound reasoning or justified assumptions. When, however, an equation is successfully applied to a given kind of process under conditions of great diversity, its value as a means of predicting phenomena must be recognized. Although the proposed equation has not by any means been thoroughly tested, it has been applied to a considerable range of moisture content for two soils of widely different character. The total volume percentage of soil moisture encountered in these tests ranges for the garden soil between 19.3 per cent and 26.0 per cent, and for the sand between 10.0 per cent and 21.5 per cent, while the value of m ranges between 51 and 77 for the garden soil and 51 and 61 for the sand (table 1). This expression, accordingly, may be considered to have considerable value for calculating the...
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Product details

  • Paperback
  • 189 x 246 x 9mm | 313g
  • United States
  • English
  • black & white illustrations
  • 1236819187
  • 9781236819185