Summary
Soil factors for tree growth are physical, chemical and biological. To control the organisms of soils and plants is probably the most difficult problem in microbiology. It is not wise to alternate neglect with feverish attention when blights or other pests become epidemic or threatening. They may be of a nutritional, preventable rather than curable nature. Pathology and tree nutrition may as well become a constant part of your activities.
References to the Literature
1. BEESON, K. C. The Mineral Composition of Crops U.S.D.A. Bulletin No. 369. March, 1941
2. FEARON, W. R. A Classification of the Biological Elements Sci. Proc. Royal Dublin Soc. Vol. 20 No. 35. February, 1933
3. WISCHHUSEN, J. F. Minerals in Agricultural and in Animal Husbandry Manganese Research & Development Foundation Cleveland 10, Ohio
4. RODALE, J. I. The Organic Forest—Editorial Organic Gardening, Emmaus, Pa. April, 1945, pp. 4-9
5. SCARSETH, GEORGE D. Growing Bananas on Acid SoilsAgriculture in the Americas, Vol. IV. October, 1944, No. 10
6. RAYNER, M. C. and NEILSON-JONES, W. Problems of Tree Nutrition Faber and Faber, Lt. London
7. ROACH, W. A. Soil Fertility and Trace Elements Soil Conservation, Washington. October, 1945 Condensed in Farmer's Digest, Ambler, Pa. January, 1946