CHAPTER V 

 IRRIGATION 



39. Moisture Requirements of Plants. Water plays a 

 most important part in all stages of plant growth. Mois- 

 ture is necessary for seed germination and is no less necessary 

 to the seedling and plant. The soil may be properly pre- 

 pared and there may be an abundance of properly balanced 

 fertilizer, but unless sufficient moisture is present in the soil 

 the plant can make but little growth or get but little benefit 

 from the fertilizer supplied for it. 



Water is a solvent of plant foods. It also acts as a 

 carrier of plant food in solution, and holds plant foods in 

 solution in the soil. Moisture is necessary for the action 

 of friendly bacteria, and by carrying solvent acids to the 

 plant food present in the soil, it makes the plant food avail- 

 able to the plant. 



Vegetables are composed very largely of water; in some 

 cases they are over 90% water. The plant juice, or sap, 

 is composed very largely of water, it thereby becoming the 

 principal agent in the carrying of plant food from the soil 

 to the various parts of the plant. Enormous quantities of 

 water are transpired during the life of the plant, several 

 hundred pounds of water being necessary for the making 

 of a pound of dry matter. 



Irrigation may be looked upon as insurance against 

 drought. With a plentiful supply of water the gardener is 

 independent of the uncertainties of rainfall. Sufficient 



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