1922.] The Purchase of Compound Manures. 569 



as to whether the sample is representative of the bulk will be, 

 as far as possible, avoided. 



In cases where the seller refuses to give an invoice as required 

 by the Act, the purchaser should communicate with the Official 

 Sampler, who will generally deal with the matter under the Act. 



The real significance of many of the terms used to describe 

 poultry foods is very doubtful and buyers should endeavour to 

 obtain a full desci-iption of the article, and should not be contented 

 w^th the name only. 



****** 



Many farmers are in the habit of purchasing compound or 

 complete manures. This procedure certainly saves the trouble 



TT, T3 ii f mixing artificial manures on the farm. 



The Purcnase Ol ^^^^ different crops and 



Compound Manures.^,.^^^.^^^ fields have different manurial 

 requirements, and in each case a mixture of manurial ingredients 

 in different proportions is likely to be required. Examples of 

 mixtures suitable for different crops in various cases and hints 

 on the mixing of manures are given in the Ministry's Leaflet 

 No. 344. 



No farmer should order a compound manure until he has 

 obtained from the vendor and carefully studied an analysis of the 

 manure in question. The agricultural value of a manure 

 depends on the amount of plant food — nitrogen, phosphates and 

 potash — which it contains, and on the form in wliich these three 

 foods are offered to the crop. 



Suppose a farmer is offered a ton of manure containing, say, 

 5 per cent, (or 1 cwt.) of nitrogen, 15 per cent, (or 3 cwt.) of 

 soluble phosphates, 5 per cent, (or 1 cwt.) of insoluble phos- 

 phates, and 2} per cent, (or } cwt.) of potash. What should he 

 pay for it? Certainly little more than the sum at which he can 

 purchase, and, if required, mix, artificials of recognised agi'icul- 

 tural value containing the same amount of fertilising material. 

 Now 20 cwt. of sulphate of ammonia contain roughly about 4 cwt. 

 of nitrogen — therefore to get 1 cwt. of nitrogen, he nuist buy 

 5 cwt. sulphate of ammonia, costing to-day about £4. Again. 

 20 cwt. of superphosphate contain roughly about 7 cwt. of soluble 

 phosphate — therefore to get 3 cwt. of soluble phosphate he will 

 need to buy about 9 cwt. of superphosphate, costing to-day about 

 £2 OS. Next, 20 cwt. of steamed bone flour contain roughly 

 about 12 cwt. of insoluble phosphates — he will need, therefore, 

 about 1^ cwt. of this, costing, say, 13s. 4d. Finally, 20 cwt. 



