<P> Besides fresh meat and milk, which is as a food item not topic of this section, livestock farmers and artisans used further animal ingredients as tendons, horn, bones, bladders . Complex technical constructions as the composite bow were based on combination of animal and plant based materials . The current distribution conflict between biofuel and food production is being described as Food vs. fuel . Conflicts between food needs and usage, as supposed by fief obligations were in so far common in historical times as well . However, a significant percentage of (middle European) farmers yields went into livestock, which provides as well organic fertiliser . Oxen and horses were important for transportation purposes, drove engines as e.g. in treadmills . </P> <P> Other regions solved the transportation problem with terracing, urban and garden agriculture . Further conflicts as between forestry and herding, or (sheep) herders and cattle farmers led to various solutions . Some confined wool production and sheep to large state and nobility domains or outsourced to professional shepherds with larger wandering herds . </P> <P> The British Agricultural Revolution was mainly based on a new system of crop rotation, the four - field rotation . British agriculturist Charles Townshend recognised the invention in Dutch Waasland and popularised it in the 18th century UK, George Washington Carver in the USA . The system used wheat, turnips and barley and introduced as well clover . Clover is able to fix nitrogen from air, a practically non exhaustive renewable resource, into fertilizing compounds to the soil and allowed to increase yields by large . Farmers opened up a fodder crop and grazing crop . Thus livestock could to be bred year - round and winter culling was avoided . The amount of manure rose and allowed more crops but to refrain from wood pasture . </P> <P> Early modern times and the 19th century saw the previous resource base partially replaced respectively supplemented by large scale chemical synthesis and by the use of fossil and mineral resources respectively . Besides the still central role of wood, there is a sort of renaissance of renewable products based on modern agriculture, genetic research and extraction technology . Besides fears about an upcoming global shortage of fossil fuels, local shortages due to boycotts, war and blockades or just transportation problems in remote regions have contributed to different methods of replacing or substituting fossil resources based on renewables . </P>

What makes fruits and vegetables a renewable resource