Effects of Soil and Topographic Properties on Spatial Variability of Corn Grain Ethanol Yield

Abstract

To maximize biofuel production requires understanding relationships of soil properties and topography with variation of biofuel production within fields. The objective of this study was to determine the potential impacts of terrain attributes and soil properties on the variation of corn (Zea mays L.) grain ethanol yield at different locations within a corn–soybean [Glycine max (L.) Merr.] rotation field located in southwest Michigan. Ethanol yield at 33 geo‐referenced points in the field was obtained for the rotational corn years of 2006 and 2008. In both years, ethanol yield was significantly negatively correlated with elevation and positively correlated with soil total C, N, and organic C probably due to nutrient availability associated with these variables. Partial least square regression (PLSR) analyses were conducted between the ethanol yield and five combinations of terrain attributes, soil properties, and three‐degree polynomial of spatial coordinates, and number of factors for each analysis was selected based on leave‐one‐out cross validation. Two factors from PLSR analyses on the combination of terrain and soil properties explained about 46 and 44% of the ethanol yield variation for 2006 and 2008, respectively. Combining a three‐degree polynomial of spatial coordinates with soil and terrain attributes improved the R2 only from 0.46 to 0.50 for 2006 ethanol yield, while improved the R2 from 0.44 to 0.70 in 2008. The overall result indicates that soil and topographic properties explained most of the spatial variation in ethanol yield in the relatively dryer year of 2006, while only a small fraction of spatial variation was explained in 2008.