摘要
A large proportion of food is composed of crops and meat besides vegetables and fruits.The production of crops and meat needs a large area of land and other resources,such as water,chemical fertilizer,and pesticides.The growing world population in creases the demand for food security.Moreover,developi ng countries with highly dense populations have dramatically changed food composition from mostly crops to more meat and milk,which has forced the adjustment and optimization of agricultural production structure to supply the demand caused by these dramatic changes.
