EXPEEIMEXTS OX POTATOES WITH DIFFERENT MANURES. 299 



The deductions to be drawn from these calculations, which 

 have reference solely to the value of the manures as measured 

 by the total amount of starch produced on the acre, are almost 

 self-evident. Phosphates unaided are but of small advantage to 

 a potato crop, as, with one exception, the increase over the un- 

 manured crop is very small, although the amount of starch in 

 each tuber is raised ; insoluble phosphates are not productive of 

 good results, but aided by ammonia their value is increased. Bone 

 superphosphates takes precedence of "mineral" superphosphates, 

 (with small additional ammonia) ; ammonia and superphosphates. 

 alone are better than when potash is employed, either as kainit 

 or as potashes, not only in gross but also in nett value. 



MANURES AND THEIR APPLICATION.* 

 By Dr. A. P. Aitken, Chemist to the Society. 



There was a time not so far gone but that many here may 

 remember it when artificial manures were almost unknown, and 

 when the only manure the farm had to rely on was that which 

 was produced on the farm. In some favoured places in the 

 neighbourhood of towns additional supplies were obtainable, but 

 on the great majority of farms the land supplied its own manure. 

 In order to grow grain it was necessary to feed stock, and to the 

 feeding of this stock by far the greater portion of the land was 

 devoted. Crops of grain were grown on one part of the farm by 

 means of the farmyard manure derived from other parts of it. 

 There was no importation of manure, and no addition made to 

 the riches of the soil, but simply a transference of these from. 

 one part of the farm to another. On a well-managed farm the 

 parts of the farm supplying the manure and those receiving it 

 were so arranged that periodically every part of the arable farm 

 received in its turn an application of manure derived from the 

 rest. This system of local transference is what still prevails 

 almost everywhere. It constitutes what may be called the 

 lateral system of the farm. 



But there is anotlier system of transference going on on a farm 

 which may be called the vertical system — a transference of the 

 riches of the soil from below upwards. This is accomplished in 

 various ways. The hay, straw, oats, and fodder plants, which go 

 to nourish the stock of the farm, derive their substance not only 

 from the thin layer of soil which comes under the action of the 

 plougli but also from greater depths, from the subsoil into which 



* A lecture delivered at Berwick to the East Berwickshire Agricultural Asso- 

 ciation, 5th Novembtr 1881. 



