^•rf'il 



FlG ". — Foliage application of a liquid fertilizer. A hydraulic 

 sprayer is used in this operation. The solution was applied until it 

 began to drip from the foliage. 



circle approximately 4! 4 feet from the trunk. The 225 

 gallons of liquid fertilizer required for each treatment 

 ( three tree species, five trees each ) were prepared in a 

 300-gallon hydraulic sprayer tank having an agitator. 



Foliar Applications of Fertilizers 



In a series of foliar applications, ammonium nitrate 

 was compared with urea, and NPK alone was compared 

 with NPK plus trace elements. Ra-Pid-Gro was used for 



the NPK source, and Ra-Pid-Gro with additional minor 

 elements added was used as the NPK plus trace elements. 

 All of these materials are water soluble. Because of possible 

 foliage burn, the amount of material applied as a spray 

 was necessarily less than that used for the soil applications. 

 Ra-Pid-Gro was used at the rate of 5 pounds per 100 

 gallons of water currently recommended for foliar applica- 

 tion. For the NPK plus minor elements, three-fourths 

 pound ( 340 grams) of Peters Trace Element Mix per 100 

 gallons of spray was added to Ra-Pid-Grn. The concen- 

 tration of N used was the same in all of the foliar treat- 

 ments. The spray solution was applied to the foliage with 

 a hydraulic sprayer ( Fig. 7 ) until the solution began to drip 

 from the foliage. No effort was made to prevent run- 

 off to the soil. Three foliar sprays, the first one the third 

 week of May, were applied at approximately 1 -month inter- 

 vals each year of the experiment. All of the foliar sprays 

 were applied between 8 AM and 12 noon on days having 

 little or no wind. 



EXPERIMENTAL RESULTS OF TREE FERTILIZATION 



The increases in circumference of the experimental 

 shade trees given the various fertilizer treatments tested 

 during 1963 and 1964 are shown in Table 4. Each cir- 

 cumference figure shown for the treated trees is the average 

 obtained from five contiguous trees in a plot. The circum- 

 ference figure for each control group is an average for un- 

 treated trees of the species represented: 14 pin oaks, 12 

 white ashes, 10 honey locusts. The totals for the 2 years 

 were analyzed statistically, and significant differences be- 

 tween treatments at the KV and 5*7 levels were noted. 



TABLE 4. — Average increases in growth of three deciduous hardwoods following various fertilization treatments at Lisle, Illinois, 

 1963 and 1964. Each average for treated trees represents five contiguous trees in a plot. The averages for untreated (control) trees 

 are based on 14 pin oaks, 12 white ashes, and 10 honey locusts. 



• Significant ;<t the .". 



nlflcanl ;ii the r level 



