Turning Maize Cobs into a Valuable Feedstock

Abstract

With rising energy demand and limited resources, the need for alternative energy production is increasing. Maize cobs have an advantageous composition for the production of biofuels such as cellulosic ethanol but are currently left unused on the fields after harvest. Furthermore, cobs contain a low concentration of nitrogen (<1%). Therefore, cob harvest will not deplete soil fertility. Consequently, maize cobs are a cheap and promising source for sustainable energy production. Yet with primary focus on grain yield, no or little effort has been spent to increase cob biomass yield in addition to grain yield. Both cob and grain yield are complex inherited traits affected by the environment. Breeding of dual-purpose maize varieties with simultaneously increased cob and grain yield requires a deeper understanding of factors influencing both cob and grain development. In this article, the available knowledge on the genetics of cob formation and current and future applications of maize cob utilization are discussed to evaluate the prospects for development of dual-purpose maize varieties.

The use of cobs, a by-product of maize grain, for energy production in anaerobic digestion

“…Fibre fractions represented over 85% of the dry matter of the cob (Table 2): the hemicellulose, which could be used easily by microorganisms, was 40%; the cellulose, used in anaerobic digestion but with longer degradation times was 29%; while the lignin was over 16%. The protein, ash, lipids, macro-elements (nitrogen, phosphorus, potassium) contents were very low compared to the whole-plant maize used for silage, and confirm previous results (Jansen and Lübberstedt, 2012). The average biogas yield of the wet threshed cob was 481±39 Nm 3 tVS -1 , with a methane percentage of 52±0.7%, which resulted in a BMP of 250±20 Nm 3 tVS -1 .…”

Genetic and agronomic assessment of cob traits in corn under low and normal nitrogen management conditions

“…QTL findings were compared to findings in the recombinant inbred lines of IBMSyn4 (Lee et al 2002;Jansen and Lübberstedt 2012) using the estimated physical positions of associated markers in recombinant inbred lines (RILs) according to B73 reference sequence version 2 using the Locus Lookup tool (Andorf et al 2010; http://www. MaizeGDB.org).…”

“…If QTL effects are small and possibly environment specific, introducing single QTL using backcrossing or even transgenic approaches is not effective to improve general trait performance QTL with larger effects might be found within genetic resources with extreme cob architecture (Jansen and Lübberstedt 2012;Loesch et al 1976). Based on findings in the IBM population, selection of multiple QTL for grain yield and cob yield for example using phenotypic or genomic selection (Meuwissen et al 2001) for specific target environments are proposed.…”

“…However, increasing nitrogen prices and political decisions to protect the environment might urge farmers to limit nitrogen application (Power and Schepers 1989;Vitousek et al 1997). Therefore, dual-purpose maize varieties were proposed combining high cob biomass and grain yield potential, especially under limited nitrogen supply (Jansen and Lübberstedt 2012). Therefore, dual-purpose maize varieties were proposed combining high cob biomass and grain yield potential, especially under limited nitrogen supply (Jansen and Lübberstedt 2012).…”

Effect of water of crystallization on the dissolution efficiency of molten zinc chloride hydrate salts during the pre‐treatment of corncob biomass

“…Agro‐industrial wastes such as corn cobs are important classes of bioenergy resources. In addition to their utilization as feed‐stocks, they are also accepted for uses as energy resources in socio‐economic spheres because they do not pose a direct threat to food security . Agricultural wastes are generated in enormous amounts especially in agro‐dependent nations of sub‐Saharan Africa.…”