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Corn stover is a low value product with high moisture content at the time of grain harvest thereby making field drying an important consideration. Corn stover has been suggested as an ideal strategic feedstock for the bioenergy program because of its abundance and proximity to existing grain-to-ethanol conversion facilities. However, high moisture corn stover is difficult to handle, spoils readily, is prone to spontaneous combustion, and is a safety hazard when moldy. Compilation and analysis of data on the drying rates, quantity, and quality of the corn plant fractions are essential to the on-going analysis of the stover supply system.

This study involved monitoring the in-field dry down and biomass availability in two corn hybrids, Pioneer 32K61 and 32K64 Bt. The standing corn was sampled over a 109-day period that started roughly a week before grain physiological maturity until several weeks after grain had reached harvest moisture. The two hybrids seemed to have no visual differences in field drying rates hence their data was pooled together. Stalks had the highest moisture content and made up half of the dry plant material, excluding the grain. By the end of the study period, 213 days after planting, all components of the corn plant reached nearly the same 10-13% MC w.b. Moisture content of the stover could be estimated by doubling the grain moisture content provided that grain moisture is between 18 and 31% w.b. After physiological maturity, the dry matter content of the stalk and husk fractions declined steadily. The leaf fraction sustained substantial loses (about 74%) very rapidly, mainly due to weathering (wind and rain damage). The amount of dry stover was about 50% of the total dry plant material over the monitoring period with stalks comprising 50% of the stover dry matter at the time grain was harvested. Overall, the grain and stover each accounted for 11.6 t/ha of dry matter (5.2 t/ac), further confirming the practicality of using a 1-to-1 ratio for estimating stover dry matter from grain dry matter.