农业生产是自然与人类活动的结合物。各地的自然条件,尤其是气候条件有着重大差异,黄河中下游地区虽同属于温带,但由于山川地形及南北间距,各地热量仍存在一定差异;而东西间的 Agricultural production is a combination of nature and human activity. The natural conditions of all places, especially the climatic conditions, are quite different. Although the middle and lower reaches of the Yellow River belong to the temperate zone, there are still some differences in the heat quantity due to the mountainous terrain and the north-south spacing. However,