was divided into plots, each plot containing five contiguous 

 trees. Each plot received one of the 16 treatments. The 

 treatments were selected at random but in such a way that 

 five trees of each species received one of the 16 treatments. 

 Eighty trees of each species were treated. The remaining 

 trees ( 14 oak, 12 ash, and 10 locust) received no treatment 

 and served as controls. 



Several materials were used as sources of nutrient ele- 

 ments in the fertilizer treatments. Ammonium nitrate 

 (33.5-0-0) and urea (45-0-0) were used as sources of 

 nitrogen. When the dry form of NPK was needed, a com- 

 mercial 10-10-10 farm fertilizer was used. When a solu- 

 tion of N, P, and K was required, a commercial water- 

 soluble 23-19-17 (Ra-Pid-Gro) was used. Source materials 

 for the water-soluble fertilizer were urea, ammonium phos- 

 phate, potassium phosphate, and potassium nitrate. When 

 P and K were used in dry form, superphosphate (0-45-0) 

 and muriate of potash (0-0-60) were mixed. For soluble 

 P and K treatments, potassium mono-H phosphate 

 (K,HP0 4 ) was used. The minor elements added were 

 contained in Peters Trace Element Mix. This mix, pre- 

 pared from soluble compounds, contained the following 

 minor elements: Mn 9.0%, Fe 6.0%, Cu 3.0%, Zn 3.0%, 

 B 2.0%, Mo 0.5'/, and Mg 0.4%. 



The type and amount of fertilizer applied to the soil 

 per tree is given in Table 1. The type and amount of 



fertilizer used per 100 gallons of spray for foliage applica- 

 tion is given in Table 2. The amount of nitrogen added 

 to the soil was maintained at 6 pounds of N per 1,000 

 square feet. Although the per cent of phosphorus and 

 potassium varied slightly in the various fertilizers, an at- 

 tempt was made to add these elements to the soil at the 

 rate of 6 pounds each of P.O. and KX) ( 2.64 pounds of 

 P and 4.98 pounds of K) per 1,000 square feet. 



The 1963 soil treatments and the first foliar spray were 

 made on May 14, 15, and 16. The second foliar spray was 

 applied June 20 and the third on July 23. In 1964, each 

 tree received the same treatment it had received in 1963. 

 The soil treatments in 1964 were made on April 22. 23, 

 and 24. The foliar sprays were applied May 20, June 2-1. 

 and July 24. 



A nail was driven into the xylem of each tree approxi- 

 mately 3 feet above the ground, so that it was possible to 

 measure the trunk growth rate at the same tree height on 

 different dates. The original circumference measurements 

 were taken on May 13. 1963. Additional measurements 

 were made October 2, 1963, and October 7, 1964. Because 

 callus growth formed around each nail, the final two meas- 

 urements on all trees were made one-fourth inch above 

 the nails. 



A visual determination of foliage greenness was made 

 once each summer. Each tree was given a rating of 1 to 5, 



TABLE 1. — Soil treatments ami the rates of application to trees in experimental plots at the Morton Arboretum. Lisle, Illinois, 

 1963 and 1964. 



Plot 



Fertilizer 



Fertilizer. 

 Grams Per Tree 



Elemental Nutrients. 

 Amount Per Tree 



1,2,3 

 5,6,7 



15 



16 

 9 



10 



12 



13 



Ammonium nitrate ( 33.5-0-0) 

 Urea (45-0-0) 

 Superphosphate (0-45-0) 



+ muriate of potash (0-0-60) 

 Potassium mono-H-phosphate 

 Commercial 10-10-10 



Water soluble 2 VI 9- 17 



Commercial 10-10-10 



+ Peters Trace Element Mix 



Water soluble 23-19-17 



+ Peters Trace Element Mix 



812 



605 

 60S 

 454 

 544 

 2,724 



1,185 



2,72 t 



K5 



1,185 



85 



272g N 

 l~lz N 

 120c P 

 226g K. 



97gP; 244 gK 

 \: l20gP; 



226g K 

 J-:uN:99aP: 



I67g K 

 272gN; L20g P: 



226g K — minor 



elements 

 272g X. 99g P: 



l0 _ s; K: - minor 



elements 



TABLE 2. — Foliar treatments anil amounts used per LOO gallons of spray on trees in experimental plots at the Morton Arboretum. 

 Lisle, Illinois, L963 and I 1 .", i. 



Plot 



I ertilizei 



Fertilizer, 

 Grams Per LOO Gallons' 



Elemental Nutrients. 

 Amount Per 100 Gallons 



4 

 8 



11 



14 



Ammonium nitrate I S3.5-0-0) 



I u.i i 15-0-0) 



Watei solubl 13-19-1 



Watei soluble 13-19-1 



.v Mix 



1,557 

 1,158 



2,270 



i in 



5::c \ 

 s:: c n 



\: WOcP: 

 Ig K 

 522gN; IW.cP; 



K. • minor 

 elements 



Oak and i I ed ipproxlmatel; i i gallons of spraj pel trei approximate)} - gallons ol spraj per tree tor 



each appllcal li in 



