The Purchase of Artificial Manures. 457 



somewhat higher than that in kainit ; so that with kainit 

 at £2 gs. per ton, the market value of sulphate of potash 

 of a purity of 74 per cent, is likely to be about 



40 x 4s. 3d. - - = £8 10 o 

 With a light haulage, and specially if the manure can be 

 applied in autumn or early spring — so as to admit of 

 certain undesirable magnesia salts being washed out— kainit 

 is usually the preferable manure ; but for use at seed-time, 

 and especially when mixed with other manures, sulphate of 

 potash has advantages. 



Muriate of potash is usually placed on 

 purity of 80 to 90 per cent., corresponding to 50 to 57 per 

 cent, of potash. Taking the former quality, and adopting 

 the unit value of potash in kainit, the price of a ton would 

 work out at 



50 x 4s. od. - - = £10 o o 



Generally a unit of potash in muriate is valued at a lower 

 rate than that in kainit or sulphate of potash, so that the 

 market quotation per ton is likely to be about 



50 x 3s. 9(1. - - = £9 7 6 

 Muriate of potash, in fact, usually offers the cheapest 

 supply of potash, and for most crops it is probably as 

 effective as any potash manure, while for potatoes it would 

 seem to be superior. 



The most important example of a manure holding 

 nitrogen, phosphates, and potash is Peruvian and similar 

 g*uano. The composition varies within wide limits, but the 

 following may be taken as an example : 



Nitrogen 12 per cent, x 1 is. gd. =£7 1 o 



Sol. Phosphates 5 per cent, x is. gd. = o 8 9 



Insol. Phosphates 15 percent, x is. 3d. == o 18 9 



Potash 2 per cent, x 4s. od. = 080 



Total - - £8 16 6 



Such a manure, however, would probably be priced at a 

 much higher rate ; so that guano, like bones, would appear to 

 be still under the influence of past traditions. 



