FORAGE CROPS. 353 



and more recently I have been fortunate enough to obtain the co- 

 operation of Mr. Robert Vallentine, of Leighton Buzzard, who 

 kindly undertook to supply me with materials for my analyses. 



" iVIy 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 dis- 

 tance 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 the other by being marked as No. i, 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 washed 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 i lb. io| oz. 

 of cleaned clover-roots in an air-dried state ; an acre of land, or 

 4,840 square yards, accordingly yielded, in a depth of 6 inches, 

 3*44 tons, or 3I tons in round numbers, of clover-roots. 



" Fully dried in a water-bath, the roots were found to contain 

 altogether 44'67 per cent, of water, and on being burnt in a plati- 

 num 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. i : — 



Water 44^75 



♦Organic matter 49236 



Mineral matter 6-089 



lOO'OOO 



* Containing nitrogen ii97 



Equal to ammonia i '57! 



" Assuming the whole field to have produced 3I tons of clover- 



