▁space ▁with ▁other ▁c ash ▁cro ps ▁such ▁as ▁coffee , ▁sugar , ▁f ruits ▁and ▁veget ables . ▁It ▁is ▁well - su ited ▁to ▁semi - ar id ▁lands ▁and ▁can ▁contribute ▁to ▁slow ▁down ▁desert ification , ▁according ▁to ▁its ▁advoc ates . ▁ ▁E ffic iency ▁and ▁economic ▁arguments ▁ ▁According ▁to ▁a ▁study ▁by ▁D rs . ▁Van ▁Dy ne ▁and ▁Ray mer ▁for ▁the ▁Tennessee ▁Valley ▁Author ity , ▁the ▁average ▁US ▁farm ▁cons umes ▁fuel ▁at ▁the ▁rate ▁of ▁ 8 2   lit res ▁per ▁hect are ▁( 8 . 7 5   US   gal / acre ) ▁of ▁land ▁to ▁produce ▁one ▁c rop . ▁However , ▁average ▁cro ps ▁of ▁rap ese ed ▁produce ▁oil ▁at ▁an ▁average ▁rate ▁of ▁ 1 , 0 2 9   L / ha ▁( 1 1 0   US   gal / acre ), ▁and ▁high - y ield ▁rap ese ed ▁fields ▁produce ▁about ▁ 1 , 3 5 6   L / ha ▁( 1 4 5   US   gal / acre ). ▁The ▁ratio ▁of ▁input ▁to ▁output ▁in ▁these ▁cases ▁is ▁roughly ▁ 1 : 1 2 . 5 ▁and ▁ 1 : 1 6 . 5 . ▁Ph otos yn thesis ▁is ▁known ▁to ▁have ▁an ▁efficiency ▁rate ▁of ▁about ▁ 3 – 6 % ▁of ▁total ▁solar ▁radiation ▁and ▁if ▁the ▁entire ▁mass ▁of ▁a ▁c rop ▁is ▁util ized ▁for ▁energy ▁production , ▁the ▁overall ▁efficiency ▁of