EXPERIMENTS ON CLOVER-SOILS. 155 



First Second Third 



six inches, six inches, six inches. 



Ibs. Ibs. Ibs. 



Phosphoric acid 3,975 4,150 3,500 



Nitrogen 4,725 3,350 2,225 



Equal to ammonia 5,725 4,050 2,700 



" 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, 2|- 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 nitrogen- 

 ous 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 : 



Oganic matter* 64.76 



Mineral matterf 35.24 



100.00 



* Containing nitrogen 1.702 



Equal to ammonia 2.066 



t 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 Ibs. 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 Ibs. of clover-roots from the land 

 mown once, and afterwards left for seed, contained 51^ Ibs. 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 bay, 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-nitrogen- 

 ous, or carbonaceous matters, of which these remains chiefly, 



