Ash analyses:
The mineral matters which the potato extracts from the soil or from the fertilizers which are added thereto consist chiefly of phosphate of potash. The mean average composition of the ash of the potato is shown in the following table:[31]
| Potash (K2O), | 60.37 | percent |
| Soda (Na2O), | 2.62 | „ |
| Lime (CaO), | 2.57 | „ |
| Magnesia (MgO), | 4.69 | „ |
| Iron oxid (Fe2O3), | 1.18 | „ |
| Phosphoric acid (P2O5), | 17.33 | „ |
| Sulfuric acid (SO3), | 6.49 | „ |
| Silicic acid (SiO2), | 2.13 | „ |
| Chlorin, | 3.11 | „ |
[31] Maercker, “Handbuch der Spiritusfabrikation,” p. 99.
This analysis was made upon the so-called pure ash, deprived of its unburned carbon, and freed of sand and carbon dioxid.
Effect of fertilization on the yield and starch content:
Experience in Germany has shown not only that liberal fertilization with nitrogen is favorable to the production of a large crop of potatoes, but also that this is accomplished without decreasing the percentage of starch therein. The following table shows the increase in yield, percentage of starch, and amount of starch obtained by nitrogen fertilization, the results being expressed in hectares[32] and kilograms:
Effect of Nitrogen Fertilization on Yield and Starch Content of Potatoes.
| Variety of Potato. | Without Nitrogen. | With Nitrogen. | ||||
|---|---|---|---|---|---|---|
| Starch. | Yield of tubers per hectare. | Yield of starch per hectare. | Starch. | Yield of tubers per hectare. | Yield of starch per hectare. | |
| Percent. | Kilograms. | Kilograms. | Percent. | Kilograms. | Kilograms. | |
| Seed, | 18.01 | 20,900 | 3,780 | 18.17 | 24,870 | 4,507 |
| Champion, | 21.33 | 19,510 | 4,152 | 21.48 | 24,470 | 5,233 |
| Imperator, | 19.00 | 22,560 | 4,235 | 18.70 | 26,830 | 5,007 |
| Magnum Bonum, | 18.41 | 19,170 | 3,522 | 18.07 | 22,510 | 4,057 |
| Aurelie, | 19.47 | 18,950 | 3,653 | 19.75 | 23,550 | 4,609 |
| Reichskanzler, | 22.78 | 14,300 | 3,236 | 22.61 | 17,250 | 3,875 |
| Juno, | 19.33 | 17,590 | 3,422 | 19.92 | 20,900 | 4,199 |
| Amaranth, | 22.47 | 16,180 | 3,619 | 22.84 | 18,310 | 4,188 |
| Charlotte, | 19.42 | 17,041 | 3,305 | 19.67 | 20,774 | 4,081 |
| Gelbfleischige Zwiebel, | 19.97 | 19,888 | 3,946 | 19.91 | 21,772 | 4,323 |
| Dabersche, | 21.82 | 17,377 | 3,778 | 21.80 | 20,313 | 4,399 |
| Weissfleischige Zwiebel, | 20.51 | 16,877 | 3,442 | 20.58 | 19,501 | 3,936 |
| Schneerose, | 18.84 | 19,653 | 3,724 | 18.66 | 22,343 | 4,186 |
| Nassengrunder, | 19.08 | 19,701 | 3,725 | 22.12 | 21,889 | 4,813 |
| Gelbe Rose, | 21.09 | 16,847 | 3,547 | 20.60 | 20,177 | 4,129 |
| Hortensie, | 17.72 | 22,416 | 3,907 | 17.45 | 26,381 | 4,532 |
| Richter’s Lange Weisse, | 19.37 | 22,134 | 4,267 | 19.19 | 24,490 | 4,664 |
| Rosalie, | 18.27 | 19,866 | 3,557 | 18.25 | 22,186 | 4,003 |
| Achilles, | 21.02 | 18,886 | 3,962 | 20.93 | 20,913 | 4,376 |
| Alcohol, | 16.47 | 16,270 | 2,673 | 16.31 | 20,339 | 3,327 |
| Average, | 19.77 | 18,806 | 3,673 | 19.85 | 21,998 | 4,332 |
[32] 1 hectare = 2.471 acres. 1 kilogram = 2.205 pounds.