“Here, again, as might naturally be expected, the proportion of nitrogen is largest in the surface, where all the decaying leaves dropped during the growth of the clover for seed are found, and wherein root-fibres are more abundant than in the lower strata. The first six inches of soil, it will be seen, contained in round numbers, 2½ tons of nitrogen per acre, that is, considerably more than was found in the same section of the soil where the clover was mown twice for hay; showing plainly, that during the ripening of the clover seed, the surface is much enriched by the nitrogenous matter in the dropping leaves of the clover-plant. “_Clover-roots_.--The roots from one square foot of this soil, freed as much as possible from adhering soil, were dried at 212°, and when weighed and reduced to a fine powder, gave, on analysis, the following results: Organic matter* 64.76 Mineral matter† 35.24 ------- 100.00 ======= * Containing nitrogen 1.702 Equal to ammonia 2.066 † Including clay and sand (insoluble silicious matter) 26.04 “A square foot of this soil produced 582 grains of dried clover-roots, consequently an acre yielded 3,622 lbs. of roots, or more than twice the weight of roots obtained from the soil of the same field where the clover was twice mown for hay. “In round numbers, the 3,622 lbs. of clover-roots from the land mown once, and afterwards left for seed, contained 51½ lbs. of nitrogen. “The roots from the soil after clover-seed, it will be noticed, were not so clean as the preceding sample, nevertheless, they yielded more nitrogen. In 64.76 of organic matter, we have here 1.702 of nitrogen, whereas, in the case of the roots from the part of the field where the clover was twice mown for hay, we have in 81.33 parts, that is, much more organic matter, and 1.635, or rather less of nitrogen. It is evident, therefore, that the organic matter in the soil after clover-seed, occurs in a more advanced stage of decomposition, than found in the clover-roots from the part of the field twice mown. In the manure, in which the decay of such and similar organic remains proceeds, much of the non-nitrogenous, or carbonaceous matters, of which these remains chiefly, though not entirely, consist, is transformed into gaseous carbonic acid, and what remains behind, becomes richer in nitrogen and mineral matters. A parallel case, showing the dissipation of carbonaceous matter, and the increase in the percentage of nitrogen and mineral matter in what is left behind, is presented to us in fresh and rotten dung; in long or fresh dung, the percentage of organic matter, consisting chiefly of very imperfectly decomposed straw, being larger, and that of nitrogen and mineral matter smaller, than in well-rotted dung.