EFFECT OF TILLAGE ON NITROGEN RESPONSE IN CORN (ZEA-MAYS L) AFTER ESTABLISHED ALFALFA (MEDICAGO-SATIVA L)

The effect of tillage arid added nitrogen fertilizer on first- and second-year corn after an established alfalfa stand was investigated in field studies near Woodstock, Ontario. Five rates of nitrogen fertilizer, ranging from 0 to 160 kg ha-1, were evaluated to determine their influence on corn growth and yield in both no-till and conventional tillage systems in the first and second years of corn following alfalfa. In the first year of corn after alfalfa, grain yield and harvest index were significantly lower with no-tilt than with conventional tillage only in 1988. First-year grain yields were independent of nitrogen fertilizer rates in both 1988 and 1989. There was no tillage by nitrogen rate interaction in either year indicating that additional nitrogen fertilizer was not required to achieve optimum corn yields with no-till relative to conventional tillage. Yields of second-year corn increased with nitrogen rate in both 1989 and 1990. Tillage systems had no apparent influence on nitrogen availability to corn grown after an established alfalfa stand.