20年来宁夏中南部山区农业生产发展分析
崔勇,马自清,田恩平

Analysis on the Development of Agricultural Production in Central and Southern Mountainous Areas of Ningxia in Recent 20 Years
Yong Cui,Ziqing Ma,Enping Tian
图3 夏、秋粮播种面积的变化
Fig.3 Changes of sowing area and ratio of summer grain and autumn grain