418 
Clover as a Preparatory Ci-op for Wheat. 
A square foot of this soil produced 582 grains of dried clover- 
roots, consequently an acre yielded 3622 lb. of roots, or more 
than twice tlie weight of roots obtained from the soil of the 
same field where the clover was twice mown for hay. 
In round numbers, the 3622 lb. of clover-roots from the land 
mown once, and afterwards left for seed, contained 51 J lb. 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 1635, 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 undecomposed 
straw, being larger, and that of nitrogen and mineral matter 
smaller, than in well-rotted dung. 
The roots from the field after clover seed, it will be borne in 
mind, were dug up in November, whilst those obtained from 
the land twice mown, were dug up in September ; the former, 
therefore, may be expected to be in a more advanced state of 
decay than the latter, and richer in nitrogen. 
In an acre of soil after clover-seed, we have — ■ 
lbs. 
Nitrogen in 1st 6 inches of soil 4725 
Nitrogen in roots .. .. 51i 
Nitrogen in 2ud 6 inches of soil 3350 
Total amount of nitrogen per acre in 12 inclies of soil 8I265 
Equal to ammonia 98G7 
or in round numbers 3 tons and 12\ cwts. of nitrogen per acre, 
equal to 4 tons 8 cwts. of ammonia. 
This is a very much larger amount of nitrogen than occurred 
in the other soil, and shows plainly that the total amount of 
nitrogen accumulates, especially in the surface soil, when clover 
