Abstract: Exploration of the characteristics and driving factors of soil acidification in peanut planting areas is of great significance in providing theoretical basis for the improvement of peanut planting soil acidification. Soil pH and its driving factors in Zhengyang County, a typical peanut planting area in southern Henan were obtained through data collection and field sampling methods. The temporal and spatial variations of soil pH were analyzed using GIS technology. Their key influencing factors were identified by the boosted regression tree (BRT) model. The results showed that soil pH of peanut planting area in Zhengyang County generally showed a decreasing trend. Soil pH declined from 7.06 in 1980 to 5.15 in 2020. The area of weakly alkaline and neutral soil decreased significantly, while the area of acidic soil increased. From 1980 to 2020, the variation range of soil pH with the largest change in area was -2.0 to -1.5, accounting for 51.9% of the whole county’s area. The most serious soil acidification occurred in lime concretion black soil, while soil pH decreased to a lesser extent in paddy soil and fluvoaquic soil. The BRT analysis showed that cation exchange capacity (CEC) was the most important factor affecting the spatial variation of soil pH in 2020, with a contribution rate of 26.2%, followed by available potassium content (AK), annual mean precipitation (AMP), soil organic matter content (SOM) and total nitrogen content (TN), with contribution rates of 11.0%, 7.7%, 7.2%, and 6.9%, respectively. Soil pH increased with increasing soil CEC, AMP, AK and SOM, but decreased with increasing soil TN. In conclusion, soil acidification of summer peanut planting in Zhengyang County is serious, especially in lime concretion black soil region, and with the characteristics of universality and local severity. Among all the factors examined, CEC is the most important driving factor for the spatial variation of soil pH. In the future, water and fertilizer management should be optimized to improve soil organic matter and nitrogen use efficiency by maintaining the balance of base ion pool in soil, so as to effectively inhibit soil acidification in peanut planting areas.

Key words: peanut growing area, soil pH, spatiotemporal characteristics, driving factor, boosted regression tree