Tillage and crop residue effects on soil nitrate under three years of corn (Zeamays L.) on land previously in corn and forage crops

A 3-yr field study in Quebec assessed effects of tillage (no-till, reduced, or conventional) × crop residues (removed or retained) on soil nitrate under corn production. Fall nitrate levels were greatest in plots without residues 1 yr after treatments began, but not thereafter. No-till and conventional tillage had similar values, but sometimes differed from reduced tillage. Key words: Nitrate, corn, no-till, reduced tillage, conventional tillage, crop residues