Submitted to: BioEnergy Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/10/2014
Publication Date: 3/10/2014
Citation: Cantrell, K.B., Novak, J.M., Frederick, J.R., Karlen, D.L., Watts, D.W. 2014. Influence of corn residue harvest management on grain, stover, and energy yields. BioEnergy Research. 7(2):590-597. Interpretive Summary: With concerns over bioenergy production, global interest is increasing in the harvesting and collection of corn stover. This is the above-ground stalk, leaves, tassels, and cobs remaining after grain harvest. However, there is uncertainty as to the sustainable management of this stover biomass with regards to soil health and crop productivity. Research is also lacking when it comes to assessing the impact of stover harvest management on stover quality—especially when targeted for bioenergy generation purposes. Focused on corn production on Coastal Plain soils as part of a larger corn stover regional research partnership, we (1) quantified the gross energy available in various corn stover fractions and (2) determined the impact of stover residue removal from the system on this gross energy. Stalks from above the ear shank were the most energy dense. When combined with other plant parts from above the ear shank, the entire top half was more energy dense than the bottom half. Residue removal was not found to statistically impact gross energy content, for any plant part. However, as the experiment progressed, there was a decreasing trend in overall energy. Seasonal rainfall was noted to greatly impact stover biomass yield and energy yield. With adequate rainfall generating greater biomass, less harvestable area is required to support local power plants.
Technical Abstract: Economic, environmental, and energy independence issues are contributing to rising fossil fuel prices, petroleum supply concerns, and a growing interest in biomass feedstocks as renewable energy sources. Potential feedstocks include perennial grasses, timber, and annual grain crops with our focus being on corn (Zea mays L.) stover. A plot-scale study evaluating stover removal was initiated in 2008 on a South Carolina Coastal Plain Coxville/Rains-Goldsboro-Lynchburg soil association site. In addition to grain and stover yields, carbon balance, greenhouse gas (GHG) emissions and soil quality impact reported elsewhere in this issue, variation in gross energy distribution within various plant fractions — whole plant, below ear shank (bottom), above ear shank (top), cob, as well as leaves and stems of the bottom and top portions (n(part, year) = 20) was measured with an isoperibol calorimeter. Stalks from above the ear shank were the most energy dense, averaging 18.8 megajoules per dry kilogram (MJ/kg-db), and when combined with other plant parts from above the ear shank, the entire top half was more energy dense than the bottom half — 18.4 vs. 18.2 MJ/kg-db. Gross energy content of the whole plant, including the cob, averaged 18.28 ± 0.76 MJ/kg-db. Over the four years, partial to total removal (i.e., 25 to 100%) of above-ground plant biomass could supply between 30 and 168 gigajoules per hectare (GJ/ha) depending upon annual rainfall. At 168 GJ/ha, the quantity of corn stover biomass (whole plant) available in a 3254 km2 area (32 km radius) around the study site could potentially support a 500 megawatts (MW) power plant.