 These substances are sometimes present in the soil, but not in a form in which the plant can use them ; when thus present and unavailable, they may often be rendered available by proper cultivation or management of the soil. If they are not present in...  Elements of Agriculture: With Industrial Lessons - Էջ 59Franklin Pierce Sever - 1902 - 141 էջԱմբողջությամբ դիտվող - Այս գրքի մասին
 | 1907 - 1168 էջ
...and potash. Carbon is obtained both through the soil and from the air. These substances are sometimes in the soil, but not in a form in which the plant...through fertilizers before the crop will grow well. Soils must be in good "physical" or "mechanical" condition too. By this I mean that they must be reasonably... | |
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