based on the following scale: 1, yellow green; 2, light 

 green; 3, green; 4, moderately dark green; and 5. dark 

 green. The 1963 color ratings were made on September 9 

 and the 1964 ratings on July 24. Each recorded rating 

 was the average of the ratings made by two observers. 



Precipitation data ( Table 3 ) were obtained from the 

 nearest weather station, at Wheaton College, about 3 miles 

 from the experimental area. In both 1963 and 1964, rain- 

 fall was below average. This shortage was evident during 

 the fall and winter. Spring and summer rainfall was near 

 or above normal. 



Four currently used methods of fertilizing established 

 trees were included in the tests: surface broadcasting. 



Table 3. — Precipitation data from the Wheaton College 

 weather station, Wheaton, Illinois. 



•Normal is an average of approximately 80 years of 'lata 

 taken from records of weather stations located in the Northeast 

 Climatological Division of Illinois. 



FlG. 2. — Electric drill being used to make boles in which dry 

 fertilizer is placed in the soil around trees. I In electric-drill 

 method ot making holes is more rapid than the punch lur method, 

 but it requires a heavy-duty drill and a soui" "I I lectlicity. It is 

 especially useful when the soil is dry. 



placement of dry fertilizer in holes made in the soil, injec- 

 tion of fertilizer solutions into the soil, and foliar feeding. 



Surface Broadcasting of Fertilizers 



Since the penetration of phosphorus and potassium into 

 the soil is limited, only nitrogen was tested by surface 

 broadcasting. One of two readily available nitrogen 

 sources, ammonium nitrate and urea, supplied in the pellet 

 form, was broadcast on the soil surface around each tree. 

 The fertilizer required for each tree was weighed and 

 broadcast by hand as uniformly as possible within a circu- 

 lar area having a radius of 5Vi feet. The area treated was 

 approximately 100 square feet. Most of the root system 

 of each of the treated trees was assumed to be included in 

 this area. Nattiral rainfall was depended upon to carry the 

 ammonium nitrate and urea into the soil. 



Placement of Dry Fertilizers in Holes 



Five fertilizers were evaluated by being applied, in dry 

 form, in holes made in the soil. The fertilizers used were 

 ammonium nitrate, tirea, PK, NPK, and NPK plus minor 



FlG. 3. — Punch-bar being used to make boles in which dry 

 fertilizer is placed in the soil around trees. 



elements. In 1963, 'he soil was sufficiently dry at the time 

 of treatment to require that the holes be made with a drill 

 or a soil profile- tube. For the large amounts of NPK or 

 NPK plus minor elements needed, holes 2 inches in diame- 

 ter were made with an electric elrill (Fig. 2). For the 

 smaller amounts of N or PK fertilizers required, holes 

 were made with a soil profile tube three-fourths inch in 

 diameter. In 1964, the soil was wet at the time of treat- 

 n ic.li t and the punch-bat method of making holes was used 



i Fig i and 6) 



I he amoum ol fertilizer tor each tre< was weighed and 

 distributed equally in IS holes around each tree (Fig. 4); 



