-4- 



Zinc (,Zn): Based on optimum levels of Zn established by Warren 



Stiles7~Cornell University (See FRUIT NOTES 47(2):20-26, 1982] some 



of our orchards continue to be low in this element. W. Stiles believes 



that apple trees require approximately 2 lbs. of Zn per acre annually 



if applied as inorganic salts in dormant sprays or approximately 0.2 



to 0.3 lbs. of actual Zn applied as foliar sprays of EDTA chelates 



(3 to 5 lbs/acre) . 



********** 



EFFECTS OF TYPE OF NITROGENOUS FERTILIZER APPLIED UNDER STURDEESPUR 

 DELICIOUS TREES ON EXCHANGEABLE ELEMENTS IN THE SOIL 



William J. Lord, John Baker and Richard A. Damon, Jr. 



In a previous issue of FRUIT NOTES (Vol. 45, No. 4), we reported 

 our findings on the effects of calcium nitrate (Ca(N02)2' amnionium 

 nitrate (NH.NO^) or potassium nitrate (KNO^) applied annually from 

 1972 through 1979 on soil pH , the nutrient levels in leaves, on bitter 

 pit, and fruit calcium (Ca) levels. To briefly review these findings, 

 neither Ca(N0^)2 nor KNO, affected soil pH , whereas NH-NO^ increased 

 soil acidity. Nitrogen [N) source had little influenc? on N, potassium 

 (K) , magnesium (Mg) , or Ca content of leaves, no appreciable influence 

 on fruit Ca and no effect on the incidence of bitter pit. 



Here we present our findings on the effects of N sources applied 

 annually since 1972 on exchangeable Ca, Mg and K in the soil (Table 1) . 



Table 1. Effects of N sources applied annually since 1972 on 

 exchangeable Ca, Mg and K in the surface 6 inches of soil. 



Meq/100 g in soil of: 



Treatment 



Ca Mg 



1978 



2 



Control 

 KNOj 

 NH^NOj 

 Ca(N02) 2 



Control 

 NH^NOj 



Ca(N02)2 



8.33a 1.50b 0.77a 



z 



Untreated soil between trees. 

 y 



Numbers in a column for each year followed by a different letter 



are significantly different at odds of 19 to 1. 



