466 BOARD OF AGRICULTURE. 



Are there any other circumstances, apart from the supply of nitro- 

 genous matter in the soil, which help to account for the beneficial 

 effects of clover as a preparatory crop for wheat ? 



In order to throw some light on these questions, and, if possible, 

 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 I have been fortunate enough to obtain the co-opera- 

 tion of Mr. Robert Vallentine, of Leighton Buzzard, who 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 four inches, so that it could only 

 with difficulty be excavated to a depth of six 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 

 six inches. The soil where the clover was good may be distin- 

 guished from the other by being marked as No. 1, and that where 

 it was bad as No. 2. 



Glover Soil No. 1, (Good Glover.) 



The roots having first been shaken out to free them as much as 

 possible from soil, were then washed once or twice with cold dis- 

 tilled 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 six inches, 3.44 

 tons, or 3J tons in round numbers, of clover roots. 



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

 altogether 44. C7 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. 1 : 



