Tillage treatments have an important effect on soil microstructure characteristics, water thermal properties and nutrients, but little is known in the newly reclaimed cultivated land. For the reason, a long-term field study was to evaluate the tillage effects on soil physicochemical properties and crop yield in newly reclaimed cultivated land via the macroscopic and microscopic analysis. Three tillage treatments were tested: continuous conventional moldboard plow tillage (CT), sub-soiling/moldboard-tillage/sub-soiling tillage (ST) and no-tillage/sub-soiling/no-tillage (NT). Under CT, the microstructure was dominated by weakly separated plates structure and showed highest bulk density (BD) (1.49 g cm−3) and lowest soil organic matter (SOM) (3.68 g kg−1). In addition, CT reduced the capacity of soil moisture retention and temperature maintenance, resulting in aggregate structure deterioration and fragility. Unlike CT, the soil was characterized by moderately separated granular structure and highly separated aggregate structure under conservation tillage practice of ST and NT. NT was associated with the highest soil moisture content (20.42%), highest quantity of macroaggregates (> 0.25 mm) by wet-sieving (34.07%), and highest SOM (6.48 g kg−1) in the surface layer. Besides, NT was better able to regulate soil temperature and improved the values of geometric mean diameter. Under NT and ST, a stable soil structure with compound aggregates and pores was formed, and the maize yield was increased by 12.9% and 14.9% compared with CT, up to 8512.6 kg ha−1 and 8740.9 kg ha−1, respectively. These results demonstrated the positive effects of NT and ST on soil quality and crop yield in newly reclaimed cultivated land.

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.

Aiming at the problems of soil poor and the decrease of cultivated land in the alluvial fan area in the northern slope of the Qinling Mountains, the selection of suitable alternative soil-forming materials to improve the soil in the piedmont area could provide a scientific reference for the improvement of soil quality. Therefore, we chose six different alternative soil-forming materials treatments, including vermiculite (M1), perlite (M2), clay shale (M3), gravel (M4), sand (M5), and soft rock (M6), which mixed with soil at a ratio of 0.5 L·m2 for field soybean planting experiments, respectively. The results showed that the order of soybean plant height from high to low in 6 different alternative soil-forming materials was M2> M6> M3> M5> M4> M1, the chlorophyll value of M2 and M3 was larger than that of the other four treatments, and the range of increase was 20.9%-26.6%, the figures showed M2 treatment was the most suitable for soybean plant growth. For soybean root dry weight, 100-grain weight and yield, the soybean root dry weight, 100-grain weight and yield under M2 and M1 treatment were larger. Comprehensive analysis of crop growth indicators and yield showed that M2 treatment was the most suitable as an alternative soil-forming material for soybean growth and soil improvement in mountainous areas.

In order to explore the effects of different fertilization treatments on soil properties and crop growth during the maturation of raw soil, a pot planting experiment with different fertilization treatments was carried out. Three fertilization treatments were set up in the experiment: single organic fertilizer treatment (OF), pollution-free fertilization treatment (NP), and conventional fertilization treatment (CF). The compactness of different soil layers,maize plant height, Chlorophyll value and above-ground biomass under the three fertilization treatments were measured. The experiment results showed that: compared with CF treatment, OF and NP fertilization treatment can better improve soil compaction and increase the plant height and leaf green value of maize, the chlorophyll value of maize under OF and NP treatments increased by 22.6% and 10.6%, and the plant height of maize increased by 58.0% and 31.8% respectively. The order of the magnitude of change of soil compaction in different soil layers was CF> NP> OF. Under conventional CF treatment, the maximum compactness value of 20 cm soil layer was 1426 kPa. For the aboveground biomass of maize, the aboveground biomass of maize under OF and NP fertilization treatments were significantly higher than that of CF fertilization treatment (P<0.05). In summary, OF and NP fertilization treatments can help improve the compaction of raw soil and the growth characteristics of crops, and increase the productivity of raw soil.