7.8 Manuring of Swedes and Potatoes. 



The most profitable artificial mixture for use without dung" 

 was found to consist of 5 cwt. basic slag, 4 cwt. kainit, 1 cwt. 

 nitrate of soda, and f cwt. of sulphate of ammonia, at a cost 

 of 38s. per acre. A similar mixture, containing 7 cwt. of 

 superphosphate in place of 5 cwt. slag, produced 12 cwt. 

 more roots, but at an extra cost of 10s. Bone meal, when 

 used with dung, did fairly well as compared with equivalent 

 •amounts of superphosphate, nitrate, and sulphate ; but in 

 the absence of dung, bone meal made a poor substitute for 

 the more soluble manures. 



On five farms, where the soil was found to be most 

 deficient in available phosphates, the soluble phosphate in 

 superphosphate produced an average increase of 14I tons per 

 acre over the plots which received no phosphates ; whilst the 

 same quantity of insoluble phosphate in slag and in bone meal 

 produced respectively 14! and 131 tons. With regard to 

 the latter, there was some evidence that the smaller average 

 crop was due to the fact that half of the nitrogen for the 

 bone meal plot was supplied in an insoluble form. It would 

 appear that as sources of phosphate both basic slag and bone 

 meal proved to be perfect, and, in one case at any rate, 

 profitable substitutes for superphosphates. 



As in former years, heavy dressings of dung did not prove 

 profitable on the average of these experiments, and, though 

 in certain cases they may prove economical, present experi- 

 ence is held to point to dressings of not more than 12 tons 

 {18 to 20 loads) as being the most suitable. 



An experiment on the manuring of potatoes was conducted 

 by the Agricultural Department of the Durham College of 

 Science at six farms in the county of Durham in 1900. The 

 results on five of the farms (in one case the soil proved unsuit- 

 able for the experiment) showed that a dressing of 1^ cwt. 

 sulphate of ammonia, if cwt. superphosphate, and J cwt. 

 sulphate of potash, costing 23s. per acre, proved to be a very 

 profitable addition to 12 tons of farmyard manure, and 

 slightly more profitable than double the quantity of artificials. 

 The most profitable mixture of artificials for use without 

 dung consisted of i\ cwt. sulphate of ammonia, 3 \ cwt. of 

 superphosphate, and 3 cwt. of sulphate of potash. This 

 mixture cost 54s. 6d. per acre. It seems probable that it 



