“The mineral portion, or ash, in 100 parts of clover-hay, consists of:
| Phosphoric acid | 7.5 |
| Sulphuric acid | 4.3 |
| Carbonic acid | 18.0 |
| Silica | 3.0 |
| Lime | 30.0 |
| Magnesia | 8.5 |
| Potash | 20.0 |
| Soda, chloride of sodium, oxide of iron, sand, loss, etc. | 8.7 |
| 100.0 |
“Let us suppose the land to have yielded four tons of clover-hay per acre. According to the preceding data, we find that such a crop includes 224 lbs. of nitrogen, equal to 272 lbs. of ammonia, and 672 lbs. of mineral matter or ash constituents.
“In 672 lbs. of clover-ash, we find:
| Phosphoric acid | 51½ | lbs. |
| Sulphuric acid | 29 | " |
| Carbonic acid | 121 | " |
| Silica | 20 | " |
| Lime | 201 | " |
| Magnesia | 57 | " |
| Potash | 134½ | " |
| Soda, chloride of sodium, oxide of iron, sand, etc | 58 | " |
| 672 | lbs. |
“Four tons of clover-hay, the produce of one acre, thus contain a large amount of nitrogen, and remove from the soil an enormous quantity of mineral matters, abounding in lime and potash, and containing also a good deal of phosphoric acid.
“Leaving for a moment the question untouched, whether the nitrogen contained in the clover, is derived from the soil, or from the atmosphere, or partly from the one, and partly from the other, no question can arise as to the original source from which the mineral matters in the clover produce are derived. In relation, therefore, to the ash-constituents, clover must be regarded as one of the most exhausting crops usually cultivated in this country. This appears strikingly to be the case, when we compare the preceding figures with the quantity of mineral matters which an average crop of wheat removes from an acre of land.
“The grain and straw of wheat contain, in round numbers, in 100 parts:
| Grains of Wheat. | Straw. | |
| Water | 15.0 | 16.0 |
| Nitrogenous substances, (flesh-forming matter)* | 11.1 | 4.0 |
| Non-nitrogenous substances | 72.2 | 74.9 |
| Mineral matter, (ash) | 1.7 | 5.1 |
| 100.0 | 100.0 | |
| * Containing nitrogen | 1.78 | .64 |