过往沙漠的南部边界比现在的边界更靠北，而半干旱的草原和较浅的淡水湖泊覆盖了现在干旱平原的大部分地区。
The southern frontier of the desert was far to the north of where it is now, while semiarid grassland and shallow freshwater lakes covered much of what are now arid plains.
在19世纪80年代，美国中部的高地平原大草原是由农民和牧场主开垦的。
The vast grasslands of the High Plains in the central United States were settled by farmers and ranchers in the 1880s.
农田在许多方面的改善与灌溉相关，但是北美洲和印度西部大草原和平原地区的一些雨育农田及牧场也得到改善。
Many gains in cropland are associated with irrigation, but there are also swaths of improvement in rain-fed cropland and pastures in the prairies and plains of North America and western India.
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