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Title: Nutrient removal as a function of corn stover cutting height and cob harvest

item Johnson, Jane
item Wilhelm, Wallace
item Karlen, Douglas
item Archer, David
item Wienhold, Brian
item LIGHTLE, DAVID - Natural Resources Conservation Service (NRCS, USDA)
item Laird, David
item Baker, John
item OCHSNER, TYSON - Oklahoma State University
item Novak, Jeffrey
item Halvorson, Ardell
item Arriaga, Francisco
item Barbour, Nancy

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2010
Publication Date: 10/1/2010
Citation: Johnson, J.M., Wilhelm, W.W., Karlen, D.L., Archer, D.W., Wienhold, B.J., Lightle, D.T., Laird, D.A., Baker, J.M., Ochsner, T.E., Novak, J.M., Halvorson, A.D., Arriaga, F.J., Barbour, N.W. 2010. Nutrient removal as a function of corn stover cutting height and cob harvest. BioEnergy Research. 3:342-352.

Interpretive Summary: Corn stover, leaves, stems and cobs that remain after the grain is harvested have the potential to be used as a feedstock for bioenergy production. More plant nutrients are removed from a field when stover is harvested compared to harvesting only grain. Therefore, harvesting stover may change fertilizer requirements for corn production. Some elements such as chloride and potassium, found in corn stover, can cause problems when processing corn stover for bioenergy. We reported the nutrient concentrations in stover at various heights above the ground. We calculated the amount of each element that would be removed from the field depending on cutting height or if only cobs were harvested. We found that corn cobs have more carbon and less of other elements compared to stover (without the cobs) above and below the grain-containing ear. We estimated that the fertilizer cost to replace nitrogen, phosphorus and potassium removed when harvesting cobs only would be about half as much as the fertilizer cost to replace nutrients if all of the stover (including the cobs) were harvested above the ear. In general, harvesting cobs plus stover from the ear upward at grain harvest provided a higher quality feedstock with less total nutrient removal than harvesting the whole plant. Impact: This information is beneficial to people in the bioenergy industry who are interested in feedstock quality of corn stover to be used for fermentation or thermochemical energy conversion. It is also useful for producers, agronomists, and crop consultants trying to balance soil fertility when nutrients are removed with harvested stover. The information will also help to ensure the sustainability of the fledging biofuel industry in the United States and elsewhere.

Technical Abstract: One-pass harvest equipment has been developed to collect corn (Zea mays L.) grain, stover, and cobs: three plant components that can be used as bioenergy feedstock. Nutrients removed in these feedstocks have soil fertility implications and affect feedstock quality. The study objectives were to quantify nutrient concentrations and potential removal as a function of vertical cutting height, plant organ, and physiological growth stage. Plant samples were collected in 10-cm increments, at seven diverse geographic locations, at two maturities, and analyzed for various elements. Nutrient concentration at harvest averaged 5.0 ± 0.3 N g kg-1, 0.42 ± 0.06 P g kg-1, and 6.8 ± 0.77 g K g kg-1 in cobs, 7.1 ± 0.41 N g kg-1, 0.98 ± 0.22 P g kg-1 and 9.2 ± 1.12 K g kg-1 in the stover above the ear and 6.4 ± 0.25 N g kg-1, 0.80 ± 0.17 P g kg-1 and 11.8 ± 1.51 K g kg-1 in stover below the ear (stover segments exclude cobs). On average, the cost to replace N, P and K was about $5.60 Mg-1 cob harvested, $11.90 Mg-1 in stover above the ear (excluding cobs) and $30.60 Mg-1 all stover including cobs. Collecting cobs or cobs plus stover from the ear upward provided a higher quality feedstock with less total nutrient removal than harvesting the whole plant. This information will enable producers to balance soil fertility by adjusting fertilizer rates and to sustain soil quality by predicting C removal for different harvest scenarios. It also provides elemental information to the bioenergy industry.