19^ The Canadian Horticulturist. 



^ ) COMPLETE MANURES. 



immK^ HE term " complete manure " is used to name such combination 

 of fertilizing materials as will supply all the elements necessary 

 to normal plant growth. As the principal ingredients needed to 

 support fertility in ordinary farming operations are practically 

 limited to nitrogen, potash and phosphoric acid, a manure con- 

 taining these three may be understood to be in fact a complete 

 manure. The simple fact that a manure contains these elements 

 is not enough ; it must contain them in certain definite propor- 

 tions. A manure may contain sufficient nitrogen, for example, 

 to produce a yield of 30 bushels of wheat per acre ; sufficient 

 phosphoric acid for 25 bushels, and potash for 20 bushels only. Such manure 

 will have an agricultural efficiency of 20 bushels, and the excess of nitrogen and 

 phosphoric acid will, so far as that particular crop is concerned, be wholly 

 useless. Not only useless, but largely lost, as unless the catch crop method is 

 practised, the fertilizing elements not assimilated either take unavailable forms, 

 or are dissipated by drainage and other causes. Even catch crops are but 

 slightly efficacious ; the soil, already exhausted of available potash by the wheat, 

 is unable to supply materials needed, and though the catch crop may require 

 relatively less potash than the wheat, this difference between crops is so small 

 that little economy is possible. 



The lesson indicated is : The crop producing value of a manure is mea- 

 sured by its lowest fertilizing ingredient. It is true that some soils contain 

 naturally varying stores of plant food in an available form. It is also true that 

 these stores are rarely or never balanced economically. If such supplies were 

 easily measurable, a fertilizer could well be compounded to profit from same ; 

 but such stores of plant food are subject to constant change and dissipation ; a 

 method of culture giving fair results one season, may prove disastrous the season 

 next following. 



It must be understood that these remarks apply more particularly to the 

 farms of the North and East, which have been so systematically exhausted by 

 diversified cropping, that the elements of plant food in any available form are 

 almost uniformly deficient. In the West and parts of the South, cropping has 

 been as yet less searching, either through a lessened period under cultivation, or 

 absence of a wide diversification of crops grown. In this latter territory, instances 

 are frequent in which incomplete manures have been used for many years with 

 some success, but the principle remains the same ; the plant must have the chief 

 elements of fertility in certain proportions, in a particular time, and in an avail- 

 able form. By trusting to chance in these proportions, the average of agricul- 

 tural production has been brought to a very low ebb indeed. 



The farms of the East and North have been practically exhausted of their 



