Soil moisture and temperature are both significant factors for crop growth and development. They are also the main influencing factors of regional climate change. In the context of climate change, the relationship between soil moisture and soil temperature is not only important for explaining the mechanism of moisture and temperature interaction, but also provides scientific suggestions for agricultural production. Since the accurate measurement of soil moisture and temperature is difficult, their relationship remains poorly understood. Here, based on real-time field observation in a potato field in Wuchuan County, Inner Mongolia, China, the change characteristics of soil moisture and temperature under different water level treatments were analyzed, and their relationships were disclosed. The results show that there was an inverse proportional relationship between soil moisture and temperature. With an increase of soil moisture, soil temperature decreased. The basic relation between soil moisture and temperature took the form of reciprocal functions (Q = 4.2 × 10³ V × (0.2 + W) × ΔT). The decline of soil moisture in the farmland will increase the soil temperature and has a negative impact on land–atmosphere interactions. The results can provide important insight into regional climate change mechanisms.

Soil moisture is closely related to the hydrosphere, atmosphere, and biosphere, which makes it one of the most significant climate variables. Using data from the National Environmental Forecasting Center (NCEP), this paper analyzes the temporal and spatial characteristics of soil moisture at a depth of 0–10 cm in China for the period of 1948 to 2014. In addition, the soil moisture’s possible interaction with air temperature is explored. Mainly using statistical analysis, the results showed that annual soil moisture decreased significantly (p < 0.01) in most areas. The tendency of decreasing soil moisture was relatively higher in spring and autumn than that in summer and winter. As to the national annual average soil moisture, there was a sudden change in the 1970s. The soil moisture had a relatively high value with a larger deviation before the abrupt change, but after that, the soil moisture was at a relatively low level with a smaller deviation. It was also found that the soil moisture at 0–10 cm showed a negative correlation with the 2-m air temperature above ground in the northern part of China, where the speed of the temperature rise was higher. The results are expected to help improve the understanding of the link between regional soil moisture variation and climate change.

Ridge–furrow planting is often applied in semi-arid regions to reduce the drought risk on crop yield under rain-fed conditions. Sunflower (Helianthus annuus L.) is widely planted in northern China and how to reduce the drought risk on sunflower production remains a significant issue. A three-year field experiment with seven treatments (a flat plot without mulching, three plastic film-mulching treatments and three non-film-mulching treatments with different ridge–furrow ratios (1.0 m:1.0 m, 1.0 m:0.5 m and 0.5 m:1.0 m)) was conducted to study the effects of the ridge–furrow rainwater harvesting system on the rain-fed sunflower. The results showed that the sunflowers in the film-mulched treatment with the larger ridge–furrow ratio (1.0 m:0.5 m) (M1R2) had greater growth advantage under drought conditions. In the dry year, M1R2 improved the yield and water use efficiency by 11.9%–107.5% and 13.8%–120.6%, respectively, and reduced the blight grain rate by 21.5%–32.5% with less evapotranspiration (ET) compared to other treatments. Based on the historical climatological data, the guarantee rate of sunflower water requirement for M1R2 was about 75%, while the guarantee rates for the other two film-mulched treatments were only about 40% and 50%. Based on the effects of drought resilience and the characteristics of precipitation, M1R2 is recommended to be the relatively optimal treatment for sunflower production in regions with similar climatic conditions to Wuchuan County in northern China.

Climate change has had a significant impact on agricultural production. It is important to evaluate the vulnerability of agricultural production to climate change. The previous methods for evaluating vulnerability are inconsiderate and unrealistic. This paper proposes an improved vulnerability assessment method, introduces the Agricultural Production System Simulator (APSIM)-wheat model to evaluate vulnerability, and uses spring wheat, in Inner Mongolia, China, as an example for evaluating the vulnerability of spring wheat under climate change. The results show that, from 1996 to 2015, the adaptability to climate change of spring wheat production, in Inner Mongolia, increased, and its sensitivity to climate change decreased. That is to say, that climatic conditions have a negative impact on spring wheat, and adaptation measures have a positive impact on spring wheat. From 1996 to 2009, the vulnerability of spring wheat production in Inner Mongolia showed a very significant increasing trend, while showing a significant downward trend during 2009–2015, which is consistent with the actual situation. The improved vulnerability assessment method can reflect the actual impact of climatic conditions on agricultural production. We expect that the new vulnerability assessment method can provide a theoretical basis for studying the impact of climate change on agricultural production.