Table 5. A comparison of candidate biofuel feedstock plant species across several parameters.

Crop	Harvestable biomass (tons/ha/yr)	Ethanol (L/ha)	Ha needed for 132.5 billion L ethanol (millions)	% of 2006 harvested US cropland: 165 million Ha (2007)	Energy output/ input ratio
Maize grain	3.1–6.4a	4266	31	19b	–
Maize stover	3.1–6.4a	2805	47	29b	–
Maize total	6.2–12.8c	3500–5400d	25–38d	15–23b	10.7c
Switchgrass	5.2–11.1e	2000–2900d	46–66	28–40b	–
Miscanthus	20.9–34.6e	8600d	15	9b	–
Prairie	3.8	1439	92.1	56b	–
Willow	6.2–12.8c	–	–	–	24.0c
Wheat total	7–14.4c	–	–	–	11.3c

^aGraham, et al.³⁹;

^bNickerson, et al.⁴⁰;

^cBörjesson and Tufvesson⁴¹;

^dZhuang, et al.⁴²;

^eFargione, et al.⁴³; – indicates no data.