Land use change of newly increased cultivated land at typical county under different geomorphic types in the Loess Plateau

Land consolidation is one of the most important measures to increase the amount of cultivated land for grain security in China. Newly increased cultivated land (NICL) can then be fully utilized to promote rural vitalization. Therefore, it is very necessary to explore the utilization direction of NICL by land consolidation, particularly with the decrease in rural population and the giant change in residents' dietary structure. Taking Yanchuan County located at the Loess Plateau as an example, this study aims to analyze the land use changes and quality distribution of NICL under different geomorphic types, including the loess tableland, beam, gully, and slope. The results show that 20.69% of NICL was converted into non-cultivated land so far. Specifically, the NICL was mainly transformed into forest and grassland. Three reasons were attributed to making the NICL change into the forest or grassland. Firstly, the benefit of orchard farming was much greater than that of grain crop farming. Secondly, orchard farming was a labor-intensive agricultural production activity that required a lot of labor time. Thirdly, rural labor was limited in the process of urbanization. Correspondingly, much less time was spent using the NICL for grain production. The NICL was then converted into forest land in the loess gully, whereas, the grassland was distributed mainly in the loess gully, tableland and beam. Among them, the apple orchard land that was converted from NICL was distributed in the loess tableland and beam. The converted area was 156062 m² from the NICL into the forest land in the loess gully, accounting for 82.27% of the total area of converted NICL into the forest land. Meanwhile, the converted areas from the NICL into the grassland in the loess gully, tableland and beam were 30528, 37358 m² , respectively, accounting for 44.97%, and 55.03% of the total area of converted NICL into grassland, respectively. The converted area was 9871 m² from the NICL into the apple orchard land in the loess tableland and beam, accounting for 92.62% of the total area of converted NICL into apple orchard land. Water resource dominated the differences in the transformation types of NICL at different geomorphic types. Even the high-quality NICL was converted into the forest land in the loess gully. Furthermore, 25.64% of the total area of the converted NICL into forest land was shared with a physical quality score of 700, 900) in the loess gully. It inferred that the NICL failed to use for the grain production in the loess gully, even with better water resources and high quality under the high benefit of orchard farming. But the NICL was abandoned and then converted into the forest land. Conversely, the NICL in the loess tableland and beam was used for orchard farming for more economic benefit. Anyway, the full utilization of NICL by land consolidation should be determined according to local conditions, as the rural population decreased and residents' dietary structure changed in China.