408 
Clover as a Preparatory Crop for Wheat. 
quantity of fibrous roots from all dirt, and the precedinq^ analysis 
distinctly shows that the ash of the clover-roots analysed by me was 
mechanically mixed with a good deal of fine soil, for oxide of 
iron and alumina and insoluble siliceous matter in any quantity 
■are not normal constituents of plant-ashes. Making allowance 
for soil-contamination, the ash of clover-roots, it will be noticed, 
contains much lime and potash, as well as an appreciable amount 
of phosphoric and sulphuric acid. On the decay of the clover- 
roots, these and other mineral fertilising matters are left in the 
surface-soil in a readily available condition ^and in considerable 
proportions when the clover stands well. Although a crop of 
clover removes much mineral matter from the soil, it must be 
borne in mind that its roots extract from the land soluble mineral 
fertilising matters, which, on the decay of the roots, remain in 
the land in a prepared and more readily available form than that 
in which they originally occur. The benefits arising to wheat 
from the growth of clover may thus be due partly to this pre- 
paration and concentration of mineral food in the surface-soil. 
The clover on the hill-side field on the whole turned out a 
very good crop ; and as the plant stood the winter well, and this 
field was left another season in clover without being ploughed 
up, I availed myself of the opportunity of making, during the 
folloAving season, a number of experiments similar to those of the 
preceding year. This time, however, I selected for examination 
a square yard of soil from a spot on the brow of the hill where 
the clover was thin and the soil itself stony at a depth of 4 
inches ; and another plot of one square yard at the bottom of the 
hill, from a place where the clover was stronger than that on the 
brow of the hill, and the soil at a depth of 6 inches contained no 
large stones. > 
Soil No. 1 {Clover thin), on the Brow of the Hill. 
The roots in a square yard, 6 inches deep, when picked 
out by hand and cleaned as much as possible, weighed in their 
natural state 2 lbs. 11 oz. ; and when dried on the top of a water- 
bath, for the purpose of getting them brittle and fit for reduction 
into fine powder, 1 lb. 12 oz. 31 grains. In this state they were 
submitted as before to analysis, when they yielded in 100 
parts : — 
Composition of Clover-roots, JYo. I. (from hrow of the hill). 
Moisture 4:-P>4: 
*Orf;anic matter 26'53 
Mineral matter GO'lo 
100-00 
Containing nitrogen '810 
Equal to ammonia "991 
