Cultivated land quality change of Wuchuan county in Inner Mongolia under background of climate change in semi-arid regions during recent 20 years

Abstract: Cultivated land quality is a key factor of national economic and social sustainable development. The change of cultivated land quality with climate change has become one of the hot research areas in global change in recent years. Based on the meteorological data, soil information and field experimental data were used, utilizing the Wageninngen method recommended by the Food and Agriculture Organization (FAO) to calculate the potential productivity of potato and spring wheat from 1989 to 2009 in Wuchuan County, Inner Mongolia, a typical semi-arid climate-sensitive area in North China. We examined the influence of climate change on production potential, the standard cropping system, and the yield. Further, by the method of regulations of Farmland classification, we used the data of potential productivity and land use to analyze the changes of natural quality grades and utilization grades under climate change. The results showed that: (1) The annual temperature of Wuchuan County increased at an average rate of 0.57℃/10a during 1967-2009. The precipitation varied greatly among the years, and the annual precipitation declined slightly over time. The soil relative humidity in soil layers 0-10 cm and 10-20 cm depth in crop growing season (April-September) in the period 1989-2009 had a decreasing trend with an average rate of 1.8%/a and 1.5%/a, respectively. Drought index increased noticeably. In conclusion, Wuchuan County was getting warmer and dryer under climate change. (2) Most of the cultivated lands were the dry lands in Wuchuan county (accounting for more than 90%), but the irrigated lands increased in recent years. The main crop in Wuchuan county was potatoes in 2009 instead of spring wheat in 1989. The planting area of potatoes increased from 8.4% to 39.8%, while spring wheat planting area decreasing from 52.1% to 17.1% in the period 1989-2009. (3) The production potential of the potatoes and spring wheat showed a declining trend under the dry warming climate in Wuchuan county. The production potential of potatoes decreased more obviously than spring wheat. Precipitation was the main factor affecting the production potential of potatoes and spring wheat. The natural quality grade index of dry land and irrigated land in the period 1989-2009 had anobviously decreasing trend with an average rate of 2.1/a and 0.5/a, respectively. The natural quality index of irrigated land was significantly higher than that of dry land. The dry land utilization grade index showed a descending trend, but the irrigated land utilization grade index showed a rising trend. The utilization grade index of the irrigated land was also significantly higher than that of the dry land, and the influence of climate change in the dry land was greater than in the irrigated land. However, the effect of land utilization by human activities in the irrigated land was greater. Therefore, as a comparative system between dry land quality and irrigated land quality, water is the major constraint to the cultivated land quality grade. This research can provide the scientific basis for formulation of the land-use system, protection and improvement of the quality of cultivated land under the background of climate change.