164 AGRICULTURE 



is to say, its capacity to fix and retain in- 

 gredients of plant food, is in inverse pro- 

 portion to the quantity of soluble manure 

 employed. The over-manuring, therefore, 

 that results from patchy distribution must, 

 at those points where excessive quantities 

 have been applied, encourage waste of 

 mamirial substances. 



Then, again, speaking generally, one will 

 obtain better results by applying, let us say, 

 20 cwt. of nitrate of soda to 20 acres, than 

 by applying the same quantity to 10 acres 

 and leaving the other 10 acres undressed ; 

 and similarly with regard to other manures 

 and other quantities. In all agricultural 

 operations it is well to bear in mind the 

 operation of what is called the Law of 

 Diminishing Returns. This law may be 

 popularly expressed by saying that as one 

 increases the dose of anything one does 

 not get a proportionate increase in the yield. 

 If, for instance, 1 cwt. of nitrate of soda 

 per acre results in an increase of 5 cwt. of 

 hay, 2 cwt. of nitrate of soda per acre will 

 not usually result in the production of 10 cwt., 

 but, of something less ; and if one goes on 

 increasing the dose one will soon arrive at 

 a point where the extra dressing will actually 

 bring about a decrease in the yield. 



