Table 2.

Tree fertilization trials in the Illinois Natural History Survey arboretum in Urbana, Illinois — 1976-1978.

Formulation	Method of application	Rate per 1000 sq ft	Diameter growth (inches)				Average	Average % increase
Formulation	Method of application	Rate per 1000 sq ft	Tulip tree	Honey locust	Pin oak	Norway maple	Average	Average % increase
20-4-8	surface	2	3.02	1.78	2.14	1.15	2.02	3.6
		4	2.88	1.83	2.10	1.25	2.02	3.6
		6	2.69	2.33	2.21	1.26	2.12	8.7
20-4-8	holes	2	2.88	1.76	2.18	1.26	2.02	3.6
		4	2.78	2.02	2.05	1.22	2.02	3.6
		6	2.90	2.14	2.44	1.27	2.19	12.3
30-3-10	surface	2	2.67	1.77	2.11	1.16	1.93	-1.0
		4	2.72	2.08	2.08	1.17	2.01	3.1
		6	2.80	2.39	2.24	1.25	2.17	11.3
34-3-7	surface	2	2.66	2.00	2.21	1.19	2.02	3.6
		4	2.35	1.89	2.22	1.27	1.93	-1.0
		6	2.89	2.08	2.36	1.17	2.13	9.2
33.5-0-0	surface	6	2.67	2.09	2.18	1.19	2.03	4.1
No treatment		0	2.66	2.00	1.96	1.18	1.95