Corn Cob Characteristics in Irrigated Central Great Plains Studies

Escalating fossil fuel cost and concern over global climate change have accelerated interest in cellulosic feedstocks, such as corn (Zea mays L.) cobs, for liquid fuel production. Little information is available about this plant organ. We compiled and summarized available cob data from several recent field studies in the Central Great Plains. Data were collected from two locations in Colorado and two in Texas that had multiple N fertilizer treatments, varying tillage systems, and different growing seasons. Cob:grain yield ratio, cob:ear ratio, cob:stover ratio, and cob N and C uptake were determined for each site. Cob yield generally increased with increasing N rate. At the high N rates, cob yield ranged from 1.44 to 2.2 Mg ha(-1). Cob:stover ratio ranged from 0.14 to 0.25 at high N fertilizer levels. The N concentration varied little among N levels at any location, varying more among locations and year, ranging from 2.52 to 5.19 g kg(-1). Nitrogen uptake at the highest N-levels ranged from 4.65 to 8.37 kg ha(-1). The relationship between final grain yield at 155 g kg(-1) water content and oven-dried cob yield was linear (r(2) = 0.75) such that cob yield increased 0.096 Mg ha(-1) for each Mg ha(-1) increase in grain yield. This study provides basic information on cob yield and quality for agronomists, and examples are discussed on how the data could be useful for determining the feasibility of harvesting corn cobs as a cellulosic feedstock.