IGO ACTION OF SOIL ON FOOD OF PLANTS IN MANURE. 



consist of a rather heavy loam, very well suited for 

 cereals, and especially for barley. 



From experiments upon the absorptive power of loam, 

 we may assume, without risk of error, that one cubic 

 decimetre ( = 61 cubic inches of loam) will absorb 2000 

 miUigrammes ( = 31 grains of potash), and 1000 milli- 

 grammes ( = 15-5 of phosphate of lime). 



The surface of an acre of loam ( = 405,000 square 

 decimetres) will therefore absorb to a depth of 1 deci- 

 metre ( = 4 inches) 805 kilogrammes ( = 1,771 lbs.) of 

 potash, and 405 kilogrammes (=891 lbs.) of phosphate 

 of lime. 



The most copious dressing with sulphate of potash 

 which Messrs. Lawes and Gilbert gave to their field 

 amounted to 500 lbs. (=270 lbs.) of potash; the most 

 copious of the supei^hosphate dressings represented 

 300 pounds of phosphate of Ume. 



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 em- 

 ployed would have penetrated no deeper than 2 centi- 

 metres, or not quite an inch, and the phosphate of hme 

 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 mches could have received 

 any considerable quantity of potash or phosphate of hme. 



At page 10 of their paper (' Eeport 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 Avhich is said 

 to be clover-sick, will have observed, that however luxu- 

 riant the plant may be in the autumn and winter, it will 

 show signs of failure in March or April.' The same fact 



