Wheat Residue Yield and Composition for Estimation of Biofuel Feedstock Potential.

Appropriate quality parameters for estimating biofuel potential of different cellulosic crops are still in question. In-vitro neutral detergent fiber digestibility (IVNDFD), along with other chemical analyses may be helpful in estimating conversion potential for future biofuel facilities.  Wheat is grown on millions of acres in the High Plains; marketing wheat straw to biofuel facilities may add value to wheat crops, by producing a secondary market for a product that currently has little or no direct economic value.  A 2-year study was initiated in 2008 at Clovis and Farmington, NM to evaluate dry matter (DM) yield and cell wall composition of winter wheat residue that may contribute to biofuel conversion.  Post grain-harvest residue (straw and chaff) was collected from 5 irrigated wheat varieties at each location.  Analyses of cellulose (CEL), hemicellulose (HCEL), lignin, and IVNDFD were combined with DM yield to give estimates of these products per ha.  In 2008, location effect was significant for DM yield, CEL yield, and IVNDFD yield, all being greater at Farmington.  However, except for CEL, there was no location effect for chemical components of the wheat varieties.  Mean DM yield was 9.1 Mg ha^-1.  Lignin may comprise as much as 7% of total DM yield.  Wheat varieties differed (P < 0.05) in DM yield, CEL yield, lignin yield, and IVNDFD yield.  Mean IVNDFD was 38.5 g 100g^-1, and ranged from 34.4 to 41.9 g 100g^-1.  First year results indicate that large amounts (>10 Mg ha^-1) of biomass can be collected after wheat grain harvest; however, when only IVNDFD is used as an indicator, potentially less than one-third of this material may be fermentable and contribute to energy production.