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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER IV THE NUTRITION AND FOOD-SUPPLIES OF WOODLAND CROPS 1 Concerning the growth of plants a large amount of information has been amassed, but we are far from possessing even an approach to a knowledge of the laws which regulate this important subject.'?RoscOE's Elementary Chemistry, 1888, page 413. All plant life is governed by what is known in agricultural chemistry as the Law of the Minimum. According to this law the essential factor occurring in minima regulates the total extent of production; whilst any given species of plant attains its finest growth and development in localities where all the essential factors are most favourably combined. These essential factors are partly of a physical, and partly of a chemical nature. To the former belong the action of warmth and of light, and to the latter carbonic acid, oxygen, and the water requisite for dissolving and holding in solution the mineral nutrients that can only be absorbed by the plant in the shape of soluble salts. Temperature makes itself felt, throughout both the soil and the atmosphere, in calling into activity the process of vegetation in spring, and in continuing it during the summer and the autumn. Most of the trees indigenous throughout central and northern Europe begin their period of active vegetation in spring when the temperature rises to 6 or 8 C., although with exotics from the warmer south a higher temperature is requisite in order to stimulate them to activity. This is a subject which has hitherto been little studied, as the following extract from Willkomm l may show: ? Despite a mean winter temperature of + 17-5 R. (71-4 Fahr.) the Beech in Madeira has a period of rest for 149 days, during which it remains leafless This strange phenomenon is to be noted also in the Elm, Silver Pop...
| ISBN-13 | 9780217058247 |
|---|---|
| ISBN-10 | 0217058248 |
| Weight | 0.72 Pounds |
| Dimensions | 9.00 x 6.00 x 0.50 In |
| List Price | $19.66 |
| Format | Paperback |
|---|---|
| Pages | 218 pages |
| Publisher | |
| Published On | 2009-08-01 |
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