TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The first plant species comprises lignin and the second plant species causes the BTU value of the first plant species to increase by causing the first plant species to grow with greater lignin content than when grown alone. The lignin content of the first plant species varies as a function of size of the first plant species, and the second plant species is a catalytic plant species that, when grown together in competition with the first plant species, causes the first plant species to grow larger than when grown alone so that the lignin content of the first plant species correspondingly increases. The first plant species is Ambrosia trifida, or Amaranthus such as Amaranthus rudis, Amaranthus hybridus and Amaranthus retroflexus. The second plant species is a tall-growing and high-lignin containing corn species and/or Sorghum species or Ambrosia trifida and Ambrosia artemisiifolia. The second plant species is one or more of G family, E series and tropical corn series hybrid corn species and number 1506 hybrid Sorghum species. The step of planting a combination of the first and second plant species involves planting Ambrosia artemisiifolia along with the first and second plant species such that a resulting combination comprises Ambrosia trifida, tall-growing, high-lignin containing corn species and/or Sorghum species and Ambrosia artemisiifolia, and where harvesting involves harvesting the resulting combination when sufficiently mature. The method further involves carrying out the selecting, planting and the harvesting events at least twice in a single growing season, where the second plant species for a first one of the selecting, the growing and the harvesting events is the tall-growing, high-lignin corn species, and the second plant species for a second one of the selecting, the growing and the harvesting events is the tall-growing, high-lignin Sorghum species. The method further involves selecting the second plant species having a BTU value that is within a predefined range of BTU values, where the predefined range of BTU values is greater than or equal to the range of BTU values of the first plant species. The method further involves selecting either of the first and second plant species to have resistance to root pests including at least one of corn borer insects and stalk-boring insects. The step of harvesting involves cutting the combination of the first and second plant species at a predetermined height above the ground, where the predetermined height being selected to minimize at least one of dirt spatter and silicon dioxide on the cut combination of the first and second plant species. The step of planting a combination of the first and second plant species further involves planting a third plant species along with the first and second plant species such that a resulting combination comprises the first, second and third plant species, the third plant species being selected to at least temporarily supplement one of the first and second plant species. The step of processing involves processing the harvested combination to produce bio-mass, and processing the bio-mass to produce ethanol, bio-gas, bio-fuel and bio-oil. The method further involves mixing additional phosphorus with base fertilizer to form a modified fertilizer, and fertilizing the planted Ambrosia trifida or Amaranthus with the modified fertilizer. The base fertilizer is a nitrogen-phosphorus-potassium fertilizer. EXAMPLE - No suitable example given.