Variation Characteristics of Particle Surface Electrochemical Properties during the Improvement of Reclaimed Soil from Hollow Village in Loess Area

Soil surface electrochemical properties, such as specific surface area and surface charge number, are important indexes to evaluate the agricultural soil quality change. However, there is not enough focus on the effect of different improved materials on the reclaimed soil surface electrochemical characteristics. Therefore, we selected maturing agent (TM), fly ash (TF), organic fertilizer (TO), maturing agent + organic fertilizer (TMO), fly ash + organic fertilizer (TFO), and no modified material (CK) treatment for 5 years of field location experiments to study the effects of different improved materials on the surface electrochemical properties of reclaimed soil from abandoned homestead. The results showed that, compared with CK treatment, the specific surface area, surface charge number, and surface charge density of reclaimed soil increased to 11.36–14.05 m2 g−1, 13.49–18.58 cmol kg−1, and 1.14–1.76 C m−2 after five years of application of different improved materials, respectively, and the number of surface charge under TFO, TMO, and TO treatment increased by 28.9%, 25.2%, and 37.7% compared with CK, respectively. Meanwhile, the specific surface area increased significantly (p < 0.05), showing an order of TFO > TMO > TO > TF > TM > CK. The surface electric field strength can reach the order of 108 V m−1. The statistical analysis results suggest that the contents of soil organic matter (SOM), silt, and clay were positively correlated with the soil surface electrochemical properties, which were the main factors for the changes of reclaimed soil surface electrochemical properties. Our research conclusion shows that in the process of reclamation of abandoned homestead in Loess Plateau, the application of different materials is helpful to improve the soil surface electrochemical properties, among which the organic–inorganic TFO treatment was a suitable improved material treatment for improving the surface electrochemical properties and fertility of reclaimed soil.