明清以来美洲作物的引种推广对经济社会发展的影响——以山东为例(1368-1949)

由于美洲作物具有耐旱、耐瘠薄、高产等特性决定其在中国北方旱作区得以大面积的快速推广。花生、烟草和棉花具有极高的商业价值，对我国传统的自然经济形成强大的冲击；甘薯、玉米和马铃薯等高产作物使得粮食单位面积产量和总产大幅度提高，引起饮食结构的巨大变化。在农业生产工具进步不大，农药、化肥没有出现的明清时期，美洲作物的引种推广是当时最为重要的科学技术手段，也是明清时期农业发展，人口迅速增加的主要原因。美洲作物的引种推广是明清时期生产力水平提高的标志，大土地所有者减少。小土地所有者增加，土地出现分散状态是其必然结果。

Influences of the Introduction and Extension of American Crops on Economic and Social Development in China since the Ming and Qing Dynasties——Taking Shandong as an Example (1368-1949)

American crops of high yield, which are also able to endure dry and barren soil, were extended in large areas across dry farming region in northern China. Peanuts, tobacco and cotton were of high commercial values and had a huge impact on traditional Chinese natural economy. American crops of high yield such as sweet potato, maize and potato led to noticeable increase in both grain output per unit area and total output. As a result, the makeup of diet also underwent great changes. When farm tools were not considerably improved and without pesticide and fertilizer in the Ming and Qing dynasties, the introduction and extension of American crops were the major means of scientific and technological innovation, which resulted in agricultural development and rapid increase in population. The introduction and extension of American crops symbolized the increase in agricultural productivity in the Ming and Qing dynasties. With less landowner with a large piece of land and more landowner with a small piece of land, subdivision of farmland was an unavoidable trend.