一般认为,亚洲的产稻国家能够扩大栽稻的新耕地面积已有限。但是许多产量高、生长期又能适应多种环境和耕作制度的水稻良种推广后,提高了水稻每季的产量和单位面积产量。在这种生产制度下,土壤肥力如不能提高也必需加以保持。 It is generally believed that the area of ​​newly cultivated land where Asian rice-producing countries can expand their rice cultivation is limited. However, after the popularization of rice varieties with high yield and growth stage and adaptability to various environments and farming systems, the yield and yield per unit area of ​​rice have been increased. Under this system of production soil fertility, if not improved, must also be preserved.