Fertili/iiigaiul Watering Trees 



between root growtli and top growth and between nitrogen 

 and phosphorus utiHzation. A deficient y of potassium is not 

 readily apparent in most trees and shruljs. 



The most important commercial fertilizer containing 

 potassium is potassium c hloride, conmionly called muriate 

 of potash. Potassium is distributed from the point of 

 application in the soil somewhat faster than phosphorus but 

 not nearly as rapidly as nitrogen. Fertilizers containing 

 potassium should therefore be placed in the soil and not 

 applied to the soil surface. Only roots quite near the point 

 of application are able to absorb ample quantities of 

 potassium. 



Formulations 



Most granular or crystalline commercial fertilizers contain 

 nitrogen, phosphorus, and potassium in specified amounts. 

 Some calcium, magnesium, sulfiu, and micronutrients are 

 also included either as impurities or in combination with 

 nitrogen, phosphorus, or potassium. The guaranteed 

 analysis of most fertilizers is shown on the bag as three 

 numbers, for example, 12—12—12. The first number gives 

 the percentage of nitrogen (N); the second gives the 

 percentage of phosphorus as phosphoric acid (P2O-); 

 the third gives the percentage of potassium as potash (K2O). 

 In many areas the application of all three primary nutrients 

 is not desirable, beneficial, or economical. Each of the three 

 can be purchased separately. 



The value of organic versus inorganic fertilizers is often 

 debated. Organic sources contain a much lower percentage 

 of nutrients, are slower to release those nutrients, are more 

 difficult to obtain and apply, and are more expensive per 

 pound of nutrient received. Organic fertilizers containing 

 humus, such as manure or composts, improve soil aeration, 

 soil structure, and the capacity of soil to hold water. When 

 plant ruitrients are of primary interest, the economics of 

 fertilizing definitely favor inorganic fertilizers. 



