Ash content and calorific energy of corn stover components in eastern Canada

Abstract

Corn stover is an abundant agricultural residue that could be used on the farm for heating and crop drying. Ash content and calorific energy of corn grain and six stover components were measured from standing plants during the grain maturing period, between mid-September and mid-November. Ash of stover in standing corn averaged 4.8% in a cool crop heat unit zone (2300-2500 crop heat units (CHU)) and 7.3% in a warmer zone (2900-3100 CHU). The corn cob had the lowest ash content (average of 2.2%) while leaves had the highest content (from 7.7% to 12.6%). In the fall, ash content of mowed and raked stover varied between 5.5% and 11.7%. In the following spring, ash content of stover mowed, raked and baled in May averaged 3.6%. The cob and stalk located below the first ear contained the highest calorific energy with 17.72 MJ·kg-1. Leaves and grain had the lowest energy with an average of 16.99 MJ·kg-1. The stover heat of combustion was estimated at 17.47 MJ·kg-1 in the cool zone and 17.26 MJ·kg-1 in the warm zone. Based on presented results, a partial "cob and husk" harvest system would collect less energy per unit area than total stover harvest (44 vs. 156 GJ·ha-1) and less biomass (2.51 vs. 9.13 t·dry matter (DM)·ha-1) but the fuel quality would be considerably higher with a low ash-to-energy ratio (1.45 vs. 4.27 g·MJ-1).