Abstract: Based on land cover maps and the survey data, this paper quantitatively analyzed the spatial and temporal characteristics of cultivated land on the Loess Plateau, northwest China from 1990 to 2015,and evaluated the changes in the minimum cultivated land area for grain safety. The results showed that the area of cultivated land decreased from 192 529.65 km² in 1990 to 182 688.50 km² in 2015 (decreased by 5.11%),of which the period 2000—2010 witnessed the largest change rate, with a net decrease of 8 483.00 km².The largest decrease in cultivated land was mainly distributed in central and western area of the Loess Plateau, and the finely-changed pixels were widely scattered. The areas converted from croplands (31 875.82 km²) was larger than that converted to cultivated lands (21 815.25 km²) in the period 1990—2015.The increased cultivated lands were mainly converted from grasslands and woodlands, which primarily occurred in the irrigated agricultural areas and southeastern plains of the Loess Plateau; while the decreased cultivated lands were mostly converted to grasslands and woodlands, and it was concentrated on the middle rain-fed farm areas of the Loess Plateau. In addition, the area of cultivated land converted to build land gradually increased during this period, and mainly distributed in the low-altitude plains in the southeast of the Loess Plateau. The minimum cultivated land area for grain safety decreased from 70 913.37 km² in 1990 to 33 981.64 km² in 2015, and the corresponding percentage (accounted for total cultivated land) decreased from 36.83% to 18.60%.However, the decrease of cultivated land has negligible impact on grain safety on the Loess Plateau.

Key words: cultivated land, minimum area of cultivated land demanded, variation characteristics, Loess Plateau