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Department of Soil Science
263 Soils Bldg
1525 Observatory Drive
Madison, WI 53706
(608) 262.2633
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Principal Area of Interest
Forest soils, tree nutrition, soil microbiology, fertilizers, eradicants
Appointment
Research 36%, Teaching 64%
Teaching and Research
My present research concerns fertility maintenance in tree nursery soils and forest plantations, the effects of fertilizers and eradicants on the morphological and physiological properties of nursery trees, the performance potential of planting stock, and the activity of beneficial soil organisms, particularly mycorrhiza-forming fungi. The solution of pertinent forest soils problems is pursued by studying soil and foliar analyses, greenhouse cultures, and sample plot trials.
The growth-depressing or sometimes aberrant stimulating effects of eradicants on trees impart an undesirably high top-root ratio, ineffective root systems devoid of fibrous rootlets and mycorrhizal short roots, succulent crowns, a low specific gravity of stems, and an unbalanced nutrient ratio in tissues. In some instances, the uptake of available nutrients (particularly phosphorus) by seedlings is arrested by biocide-caused immobilization of symbiotic and chelating microbes. The amelioration of biocide-treated soils is related to the introduction of amendments that assure a reasonably harmonious coexistence of eradicants with other components of the soil: fertilizers, microorganisms, and root systems.
Nursery stock is evaluated by its vigor and ability to withstand adverse climatic and biotic factors when outplanted on cutover lands. Therefore establishing a measure of the seedlings survival potential is significant. Methods for determining a Quality Index which comprises the morphological and physiological attributes of outplanted stock are being refined and validated.
To improve soil management practices while considering environmental concerns and economic feasibility, we are directing research toward precise timing of fertilizer application in relation to plant development to control both nutrient levels and nutrient balance; improve efficiency of applied fertilizers, determine effects of soil properties on mycorrhizal contributions to nutrient uptake into a nutrient uptake model, and develop improved nursery soil tests and test interpretations based on nutrient uptake models.
I teach a soil fertility laboratory course, a soil biology course, a nursery crop management course and coordinate a seminar in forest soil science in the Fall semester, and direct students in special problems. I also advise undergraduates.
Publications
Iyer, J.G. 1987. Nutrient budget for tree seedlings. p. 1-25. In Proc. Northeastern Area Nurserymens Conf., Hayward, WI.
Iyer, J.G., R.B. Corey, and S.A. Wilde. 1982. Ectomycorrhizae and nutrition of woody plants. Biol. Sci. 5:82-85. (Moscow Russia).
Iyer, J.G., and H. Kubler. 1981. Forstliches Pflanzgut: Bewertung Seines Wuchspotentials. Forstarchiv 52:96-97.
Iyer, J.G., R.B. Corey, and S.A. Wilde. 1980. Catalytic potential of mor humus layers as an indicator of biological activity. Soil Sci. Soc. Am. J. 44:171-173.
Iyer J.G., R.B. Corey, and S.A. Wilde. 1980. Mycorrhiza: Facts and fallacies. J. Arboriculture 6:213-220.
Wilde, S.A., G. K. Voigt, and J.G. Iyer. 1979. Soil and plant analysis for tree culture. (5th ed.). Oxford and IBH Publishing Co. New Delhi and Bombay.