A proportionate tobacco crop of 1,000 kilos per hectare will withdraw from the soil (reduced to the same standard of weights adopted by Mr. Cochran)—
| Pounds. | |
| Nitrogen | 168 |
| Potash | 213 |
| Phosphoric acid | 23 |
An equivalent crop of shelled corn, say, of 125 bushels per hectare, will withdraw—
| Pounds. | |
| Nitrogen | 200 |
| Potash | 135 |
| Phosphoric acid | 75 |
while a relative crop of lint cotton of 237 kilos (700 pounds) per hectare[2] will only exhaust, in round numbers—
| Pounds. | |
| Nitrogen | 114 |
| Potash | 70 |
| Phosphoric acid | 30 |
There is an analogy between these four products that makes them all comparable, in so far as all are largely surface feeders, and, as experience shows that there can be no continuing success with the last three that does not include both cultivation and manuring, we may use the analogy to infer a like indispensable necessity for the successful issue of the first.
Cultivation as a manurial factor should, therefore, not be overlooked, and all the more strongly does it become emphasized by the very difficulties that for some years to come must beset the Philippine planter in the way of procuring direct manures.
When it comes to the specific application of manures and how to make the most of our resources, we shall have to turn back to the analysis of the nut and note that, relatively to other crops, it makes small demands for nitrogen. At the same time it must not be forgotten that these chemical determinations only refer to the fruit and that, with the present incomplete data and lack of investigation of the constituent parts of root, stem, leaf, and branch, we have nothing to guide us but what we may infer from the behavior of the plant and its relationship to plants of long-deferred fruition, whose manurial wants are well understood.
It is now the most approved orchard practice to encourage an early development of leaf and branch by the liberal application of nitrogen, whose stimulant actions upon growth are conceded as the best.