摘要：Concentration in several global agricultural input industries has risen significantly; by 2009, the largest four firms in the crop seed, agricultural chemical, animal health, animal genetics/breeding, and farm machinery sectors accounted for more than 50 percent of global market sales in each sector. Factors influencing changes in market structure and concentration vary by industry and include market forces, the emergence of new technologies, and government policies. The largest agricultural input firms are responsible for a large and growing share of global agricultural research and development (R&D), and higher input prices paid by farmers partially reflect the higher quality of inputs created through private-sector R&D.
