“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 “The ash of wheat contains, in 100 parts: