Table 2. The influence on soil pH of three sources of nitrogen 

 applied annually under Sturdeespur Delicious trees since 1972. 



Soil pH under trees receiving: 



"Ca(N033 2 NH4NO3 KNO^ 



z 

 Numbers in a row followed by a different letter are significantly 

 different at odds of 19 to 1. 



In 1979 we also sampled the 20 to 24-inch soil depth and found 

 the acidifying influence of NH4NO, at these depths but the pH was 

 higher than at the 12-inch and 6- inch depths (Table 3). 



Table 3. Influence of ammonium nitrate and calcium nitrate on soil 

 pH at different depths, 1979^. 



Soil 



Soil pH under tree receiving; 



depth NH4NO3 Ca(N03)2 KNO3 



0-6 5.20b^ 6.00a 6.14a 



6-12 5.22b 5.92a 6.14a 



20-24 5.57a 6.07a 6.14a 



z 

 Applied annually since 1972 



y 



Numbers in a column followed by a different letter are significantly 



different at odds of 19 to 1. 



Influence of N Source on Elements in Leaves 



Leaf analyses showed that N and Mg were not influenced by N 

 source. In 1976 KNO3 increased K and suppressed Ca probably due 

 to the interaction between these 2 elements. In 1974, 1976 and 

 1977 the KNO3 trees were lower in foliar Ca than those fertilized 

 with Ca(N03)2- This is probably an influence of K in KNO3 rather 

 than an enhancement of Ca by Ca(N03)2 since Ca was not influenced 

 by NH4NO3. 



