Decomposition of grain-corn residues (Zea mays L.): A litterbag study under three tillage systems

Abstract

This study was undertaken to obtain litterbag decomposition data for grain-corn residues in eastern Canadian conditions, to determine tillage and/or depth effects on residue mass loss, and to compare decomposition patterns for the different plant parts that constitute the residue (cobs, stems, leaves, husks). Mesh bags containing residues were buried or left on the soil surface in grain-corn plots under no-till, reduced tillage, and conventional tillage, and retrieved over a 2-yr period. Data were obtained separately for each plant part, then used to calculate pooled totals for all residues combined, for all residues except cobs, or for stems and leaves only, to facilitate comparison with studies based on different residue mixes. Buried residues lost mass faster than surface residues. Despite low overwinter temperatures, residue mass decreased substantially between placement in November and first sampling in mid- May. Surface litterbag residues lost 20% of initial mass during this period, residues buried at 5 cm lost 33%, and those at 20 cm lost 41%. Corresponding losses from mid-May to mid-October were 21, 42 and 32%, respectively. Mass loss was fastest for buried leaves, husks and stems (89-98% loss in 2 yr) and slowest for surface cobs (32% loss in 2 yr). Key words: Corn, maize, crop residue decomposition, litterbag, no-till, tillage