FERTILIZERS. 



BY W. NEWTON, B.S.A., M.Sc. 



A CLEAR conception of the economic value of fertilizers is more important to-day 

 '*"* than at any period through which agriculture has passed. In the Province 

 of British Columbia the yields are beginning to decrease, due to the exhaustion 

 of the stores of fertility in our virgin soils. Crop-production costs have increased ; 

 unless fair yields are obtained the cost of production will be greater than the 

 value of the crop. 



Specialized fruit districts have become established. Their future productiveness 

 depends largely upon the intelligent use of fertilizers. 



In the mixed-farming districts, when a carefully chosen rotation, including a 

 clover or other legume crop, is followed, and where the grain and hay is fed on the 

 farm and the manure properly cared for, it may not be necessary to use commercial 

 fertilizers, but when the nature of the crop prevents rotation, and where very little 

 farmyard manure is produced, commercial fertilizers may be required. 



CHEMICAL ELEMENTS NEEDED BY PLANTS. 



As far as we know, there are fifteen chemical elements required for normal 

 plant-growth. There are only four that particularly interest the farmer, for the 

 others are usually found in abundance in all soils. These four are nitrogen, phos- 

 phorus, potassium, and calcium. When we speak of plant-food we usually refer to 

 these elements as nitrogen, phosphoric acid, potash, and lime. 



AVAILABILITY OF PLANT-FOOD. 



It may be surprising to know that most farm soils, even those that produce 

 poor crops, are abundantly supplied with plant-food. When poor crops are obtained 

 it means that the plant-food is not available. This fact serves to emphasize the 

 necessity of paying special attention to the numerous factors that influence the 

 availability of the plant-food in the soil. 



AERATION AND DRAINAGE. 



Foremost among these factors is the question of aeration and drainage. A free 

 circulation of air is necessary to promote the development of soil organisms that 

 assist in changing the locked-up fertility of the soil into a form available to plant- 

 growth. Without adequate drainage the air cannot penetrate the soil. Besides 

 favouring the development of soil organisms, the roots of practically all plants 

 require free air to develop normally. Air has also a direct chemical effect that 

 not only releases plant-food, but frequently oxidizes soil substances that are injurious 

 or toxic to plant-growth. 



INCREASING THE FEEDING AREA. 



Some soils are so shallow that the crop-roots are confined to a thin surface 

 strata. The limited area from which they obtain their food will frequently account 

 for the poor returns. 



MOISTURE-SUPPLY. 



The moisture-supply must be sufficient at all times during the growth of the 

 plant. The moisture in a saturated soil is not available to plants to the same extent 

 as when a soil is properly drained. Increasing the depth, improving the texture, 

 and the maintenance of an adequate humus or rotted vegetable-matter content all 

 have a direct bearing upon the supply of moisture required for plant-growth. 



