CHAPTER XIV 



FERTILIZING THE ORCHARD 



The substances that all plants need to carry on 

 their existence are air, water, phosphoric acid, 

 potash, nitrogen, lime, and to a small degree such 

 minerals as magnesium and iron. 



Air is, of course, plentiful and free to all, but it is 

 the only requisite of plant life that is. Water is 

 also a most important factor governing the develop- 

 ment of the plant, as the greater portion of the living 

 plant consists of water. 



Water, moreover, by dissolving many of the plant 

 foods contained in the soil, reduces these to a con- 

 dition in which they can be easily assimilated by the 

 roots of the plants. This action of water in making 

 available large quantities of plant food is the reason 

 for the increased fertility shown by all classes of 

 land when irrigated ; but if watered in excess of 

 plant requirements, the available plant foods are 

 apt to be washed too deeply into the sub-soil for the 

 roots to reach, and so are lost to the plants. Water, 

 therefore, although not a fertilizer in the ordinary 

 sense. of the word, is nevertheless, on account of its 

 forming the greater portion of tire substance of 

 living plants, the first requisite that must be added 

 to the soil to promote plant growth. Hence the first 

 essential to successful crop production is an ample 

 rainfall or where this does not exist, then the land 

 must be supplied with sufficient water by means of 

 irrigation. 



