CLOVER AS A PREPARATORY CROP FOR WHEAT. 4g9 



This ash was obtained from clover roots, which yielded when 

 perfectly dry, in round numbers, 8 per cent, of ash. Clover roots 

 washed quite clean, and separated from all soil, yield about 5 per 

 cent, of ash ; but it is extremely difficult to clean a large quantity 

 of fibrous roots from all dirt, and the preceding analysis distinctly 

 shows that the ash of the clover roots analyzed by &e was me- 

 chanically 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 phos- 

 phoric and sulphuric acid. On the decay of the clover roots, these 

 and other mineral fertilizing 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 fertilizing matters, 

 which, on the depay 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 preparation 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 plowed up, I 

 availed myself of the opportunity of making, during the following 

 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 four 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 six inches contained no large stones. 



Soil No. 1 (Clover thin), on the Brow of the Mil. 



The roots in a square yard, six 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 : 



