Clover as a Frcparatorij Crop for JVhcat. 
405 
account for the beneficial (>nects of clover as a preparatory crop 
for wheat ? 
In order to throw some light on these questions, and, if pos- 
sible, to give distinct answers to at least some of them, I, years 
ago, when residing at Cirencester, began a series of experiments, 
and more recently 1 have been fortunate enough to obtain the 
co-operation of Mr. Robert Vallcntine, of Leighton Buzzard, v/ho 
kindly undertook to supply me with materials for my analyses. 
My first experiments were made on a thin calcareous clay 
soil, resting on oolitic limestone, and producing generally a fair 
crop of red clover. The clover-field formed the slope of a rather 
steep hillock, and varied much in depth. At the top of the hill 
the soil became very stony, at a depth of 4 inches, so that it 
could only with difficulty be excavated to a depth of 6 inches, 
when the bare limestone rock made its appearance. At the 
bottom of the field the soil was much deeper, and the clover 
stronger than at the upper part. On the brow of the hill, where 
the clover appeared to be strong, a square yard was measured 
out ; and, at a little distance off, where the clover was very bad, 
a second square yard was measured ; in both plots the soil being 
taken up to a depth of 6 inches. The soil where the clover was 
good may be distinguished from tlie other by being marked as 
No. 1, and that where it was bad as No. 2. 
Clover-Soil No. 1 {Good Clover). 
The roots having first been shaken out to free them as much 
as possible from soil, were then Avashed once or twice with cold 
distilled water, and, after having been dried for a little while in the 
sun, were weighed, when the square yard produced 1 lb. 10^ oz. 
of cleaned clover-roots in an air-dry state ; an acre of land, or 
4840 square yards, accordingly yielded, in a depth of 6 inches, 
3'44 tons, or 3^ tons in round numbers, of clover-roots. 
Fully dried in a waterbath, the roots were found to contain 
altogether 44"67 per cent, of water, and on being burnt in a 
platinum capsule yielded 6"089 of ash. A portion of the dried, 
finely powdered, and well-mixed roots was burned with soda- 
lime in a combustion-tube, and the nitrogen contained in the 
roots otherwise determined in the usual way. Accordingly, the 
following is the general composition of the roots from soil 
No. 1 :— 
Water 44-G75 
*Orgauic matter 49-236 
Mineral matter G-089 
100-000 
Containing nitrogen 1 '297 
Equal to ammonia I'GTS 
