On the Failure of the lied Clover. 333 



growth of white clover, red clover^ and tares, become more pul- 

 verulent, puffy, and less cohesive, in proportion to the frequency 

 of the growth of these crops ; and this explains why these lands 

 tire of clover. The several particles of earth, by the long, deep, 

 and numerous radicles of these plants, become mechanically forced 

 from their position, and their points of contact thus rendered 

 fewer in number; and such soils comparatively become speci- 

 fically lighter in proportion to the weight of a determinate volume. 



That the soils upon which the clover is destroyed do lose the 

 cohesiveness of their particles, and, when compared with those of 

 the same chemical constitution which preserve the plant, are spe- 

 cifically lighter in proportion to the weight of a determined 

 volume, is proved by the following trials, in which a solid foot of 

 each was dug from the ground and weighed upon the spot. 



In the two portions of the field whose soil was analysed, several 

 trials of the weight of the two soils gave a difference of 6 to 71 lbs. 

 per solid foot, (of 17x17x6 inches, or 6 inches in depth,) or from 

 117 to 140 tons weight per acre over and above the failing or 

 sick portion of the field ; and this difference of the weight does not 

 arise from a difference in the specific gravity of the two soils (in- 

 deed the lighter contains more silica), but from the particles of 

 earth not being in equally close contact. 



In another field, belonging to Mr. W. Stephenson of Womersley, 

 upon the new red sandstone, which is rather peaty, and possesses 

 a subsoil of clay, one portion of it was swede turnips, which were 

 pulled off; another, potatoes; a third, white turnips, which were 

 eaten off the ground with sheep ; a fourth portion, open fallow, 

 manured with rape-dust. All these different pieces were sown 

 with barley and red clover ; but the red clover disappeared in the 

 winter from all except one, viz. the white turnips eaten off with 

 sheep, and which weighed — 



Hi lbs. per foot of 6 inches deep (or 216 tons per acre) more than the 



swedes. 

 5^ lbs. J, „ (or about 100 tons) more than the 



potatoes. 

 lOf lbs. 5, „ (or about 200 tons) more than open 



fallow. 



The treading of the sheep in eating off upon this soil added a 



power of retaining heat." (Schubler on the Physical Properties of Soil, 

 Journal of Eng. Agric. Soc, vol. i. part ii. p. 1 77.) " When different earths 

 are mixed together, a cubic inch of the mixture obtained gives a greater 

 weight than the arithmetical mean (or common average) of the earths 

 entering into the mixture, whether mixed in equal portions according to 

 weight or volume, or in other quantities." (Ibid., p. 181.) e.g. 2 parts of 

 sand, and 1 part of clay, by volume, have an arithmetical mean weight of 

 2566, while the actual weight is 2825, or an increase of 259. 



