160 ACTION OF SOIL ON FOOD OF PLANTS IN MANURE. 



copious of the superpliospate dressings represented 300 

 pounds of phosphate of lime. 



Had Messrs. Lawes and Gilbert put upon the field 

 the sulphate of potash and the phosphate of lime in a 

 state of complete solution, the whole quantity of potash 

 employed would have penetrated no deeper than 2 cen- 

 timetres, or not quite an inch, and the phosphate of 

 lime no deeper than 4 centimetres, or a little more than 

 1*6 inch. Both manures, however, were strewed over 

 the field and ploughed in ; still it cannot be assumed 

 that the layers below a depth of 8 inches could have 

 received any considerable quantity of potash or phos- 

 phate of lime. 



At page 10 of their paper (< Report of experiments 

 on the growth of red clover by different manures') 

 Messrs. Lawes and Gilbert say, ' Those who have paid 

 attention to the spread of disease in clover, on land 

 which is said to be clover-sick, will have observed, that 

 however luxuriant the plant may be in the autumn and 

 winter, it will show signs of failure in March or April.' 

 The same fact was observed in all their experiments. 

 A field on which clover had failed was sown with bar- 

 ley, and when this had yielded a rich crop, another 

 attempt was made with clover. 



1 The plants (say Messrs. Lawes and Gilbert) stood 

 tolerably well during the winter, but as the spring ad- 

 vanced they died off rapidly.' There cannot be the 

 slightest doubt about the reason of this decay ; the ex- 

 hausted subsoil had not received back any of the lost 

 conditions of fertility, and thus the plants were starved 

 as soon as they had pushed through the arable surface 

 soil, and their roots were beginning to spread in the 

 subsoil. 



If the failure of the clover was .attributable to a dis- 

 ease, this must have been of a very singular nature, as 

 the richly-manured arable soil showed no traces of it, 

 and it was only the subsoil which was clover-sick. The 

 notion that there is any disease engendered by the cul- 

 tivation of clover is refuted most completely, though 

 unconsciously, by Messrs. Lawes and Gilbert them- 



