Spatial distribution and compensation strategy of land fallow based on quality-risk in arid areas

Abstract: A diversified fallow ecological compensation is an inevitable choice for the sustainable development of agriculture in China. It is very necessary to explore the spatial distribution of fallow land for the higher efficiency of ecological compensation for fallow in arid areas. Taking the Kaidu-Kongque River basin in Xinjiang as an example, this article aims to propose different compensation strategies for different zones, thereby determining the spatial layout of fallow, considering the quality of cultivated land and risk of land degradation. The specific procedures were: 1) An evaluation index system of cultivated land quality was established to select the indicators from two aspects of soil physical and chemical properties, and cultivation convenience. A comprehensive evaluation was then made for the quality of cultivated land. 2) MEDALUS-ESAs model was selected to estimate potential risks of land degradation in the basin, where four indicators included soil, climate, vegetation and land use. 3) The Z-score was also applied for the quality score of cultivated land and risk index of land degradation. The standardized value was divided into four quadrants, according to the coordinate axis to determine the spatial distribution of fallow. Specifically, the cultivated land with "low quality and low risk" was classified as a priority fallow area, "high quality-low risk" was classified as a sub-priority fallow area, "low quality-high risk" was classified as restricted fallow areas, and "high-quality-high-risk" was classified as fallow area. 4) Different compensation strategies were finally proposed for fallow, according to different zones. The results showed that: 1) There was a fair overall quality of cultivated land in the whole Kaidu-Kongque River Basin, but slightly good in local areas. The spatial pattern of land degradation risk was "low in the northern, high in the southern". 2) The area of cultivated land located in the priority fallow area was 67 814.60 hm2, mainly distributed in the western part of Kongque River Oasis and the northeastern part of Bosten Lake. The area of cultivated land located in the sub-priority fallow was 71 784.94 hm2, mainly distributed in the northern part of the Kaidu River Oasis. The area of cultivated land located in the restricted fallow area was 80 576.89 hm2, mainly distributed in the central area of the Kongque River Oasis, the northern and southern part of Bosten Lake, and the eastern part of the Kaidu River Oasis. The area of cultivated land located in the forbidden fallow area was 107 358.03 hm2, mainly distributed in the southern part of Kaidu River and Kongque River Oases and the eastern Bosten Lake. 3) The cultivated land located in the priority fallow area was restricted by cultivated land quality. As such, the long-term fallow was necessary to combine with the quality improvement of cultivated land. The fallow compensation in the zone was determined, according to the loss of agricultural income and the cost of land improvement. Furthermore, the cultivated land located in the sub-priority fallow area was in good condition, where the fallow can be combined with agricultural water saving to implement seasonally fallow. More importantly, the fallow compensation depended mainly on the loss of agricultural income. The cultivated land in the restricted fallow area was restricted by cultivated land quality and ecological safety. Therefore, the fallow can be combined with cultivated land quality improvement and ecological protection to implement annual fallow, where the agricultural income loss, land improvement costs, and ecological protection costs standard should be considered into the fallow compensation.