EFFET DU MAGNÉSIUM ET DU pH DU SOL SUR LA LUZERNE CULTIVÉE EN SERRE DANS TROIS TYPES DE SOL DU QUÉBEC

Abstract

Aflalfa (Medicago sativa L. ’Saranac’) was grown under greenhouse conditions in order to determine changes in magnesium (Mg) response and availability following variation in soil pH. The rates of Mg applications were 0, 25, 50, 100 and 200 ppm of Mg calculated on soil dry weight basis. Soil pH was adjusted to 5.0 (or original) 6.0, 6.5 and 7.5. A 40% yield increase was recorded on Greensboro loam following Mg fertilization. The increase in yields due to Mg was 23% on the two others soil types. The Mg contents of plant and soil increased with rate of Mg applied to soil. In general, the response of alfalfa was increased by liming soils and the Mg content of alfalfa was decreased. The availability of Mg in soils was also lowered by liming. The Mg requirement of soils varied from 25 to 100 ppm depending upon pH and soil types.