502 Field Experiments on Root- Crops. 



manures were sent to about a dozen men residing in different 

 counties ; but their returns, I regret to say, in the great majority 

 of instances recorded either complete failures, mainly due to the 

 remarkable drought in the spring and early summer months 

 of 18(34 and 18G5, or results void of all practical interest, from 

 which no general principles could fairly be deduced. Desiring 

 not to burden the reader with an account of these failures, 

 I have selected for publication only such experiments as appeared 

 to me to embody points of agricultural interest. 



Experiments on Swedes in 1864. 



The object of the following experiments was to ascertain 

 whether the artificial supply of potash is characterised by any 

 marked effect upon root-crops. Simple as this enquiry may 

 appear at first sight, it is nevertheless beset with many difficulties, 

 which have to be kept steadily in view in devising a plan of field 

 experiments for its investigation. In the first place, experience 

 has shown already that most soils in a fair agricultural condition 

 neither require nor are in the least benefited by the exclusive 

 supply of potash. Good clay soils, as a rule, contain abundant 

 stores of potash to meet the wants of root-crops. On sandy soils, 

 which are naturally deficient in that element, we meet at once 

 with another difficulty, from the fact that other constituents 

 entering largely into the composition of root-crops are generally 

 but scantily represented ; and, for this reason, it cannot be 

 expected that the application to such land of a manure which 

 supplies only one essential plant-constituent will be attended 

 with any marked effect. In devising a plan of field experiments 

 care should be taken to make provision for any disturbing 

 influences arising from the chemical nature of the experimental 

 field, and the requirements of the crops under experiment. 

 ^^The cheapest form in which potash can be put on the land is 

 that of crude German potash-salts. A sample of these salts, 

 which were employed in all the following experiments, on 

 analysis was found to contain in 100 parts, — 



Moisture 11-63 



Orajanic matter "73 



Oxide of iron '34: 



Sulphate of potash 24-03 



Sulphate of magnesia 1-14 



Chloride of magnesium 12-01 



Chloride of sodium (common salt) 47-85 



Sulphate of lime '78 



Magnesia '52 



Sand -97 



100-00 



