Differences of physicochemical properties of black and light chernozem soils in 0–100 cm soil layer with different yield levels under long-term maize cropping system

Objectives Soil physical and chemical properties of black and light chernozem soils under long-term maize cropping system were studied.

Methods Eighteen representative sampling plots were randomly selected in long-term (>15 years) maize fields in central (black soil) and western (chernozem soil) regions of Jilin Province. In each plot, soils in 0–10, 10–20, 20–30, 30–50, 50–70 and 70–100 cm layers were sampled to analyze physicochemical properties. Soil samples were classified into three groups i.e., high level (HYL), middle level (MYL), and low level (LYL) according to maize yield in each region. The differences in soil physicochemical properties across the soil layers and among different grain yield levels in black and light chernozem soil were analyzed.

Results The overall soil fertility within 0–100 cm depth in black soil was higher than that of light chernozem. Soil N, P, and K contents within 0–100 cm depth of black soil were higher than those of light chernozem by 2.4%, 13.3% and 43.5%, respectively. Highest contents of soil organic matter and total N within 20–100 cm soil depth were observed in the plots of HYL in the two regions. In HYL and MYL plots, soil total and available nutrients in the topsoil (0–20 cm) were significantly higher than those in the deeper layers (20–100 cm). In black soil, an apparent soil nutrient and moisture storage section was found at 20–30 cm layer, and soil pH at 0–100 cm layer ranged from 5.15 to 7.07. The distribution of solid, liquid and gas in soil were close to the ideal situation. The value of the generalized soil structure index (GSSI) within 0–100 soil layer decreased with yield level (i.e., HYL>MYL>LYL). Soil water content in HYL plots was higher than those of MHL and LML plots. Total P content within 0–100 cm soil layer in HYL was close to that in MYL plots. Available K content within 0–20 cm soil layer in HYL and MYL were greater than that in LYL. No special section, which could play role in water and nutrient retention, was found in light chernozem; however, significant correlation was found between soil physico-chemical parameters of 20–30 cm layer and yield. Soil pH within 0–100 cm layer in light chernozem ranged from 6.61 to 8.31. The accumulation of nitrate in 70–100 cm layer in HYL plots accounted for 5.2% of the total soil storage in 0–100 cm layer. Obvious decrease in soil pH was found in the two soils, especially in LYL plots.

Conclusions In the black soil region, the physico-chemical properties of soil within 30–50 cm layer were strongly correlated with maize yield. The capacity of soil nutrients supply below 20 cm soil layer in HYL plots was important for sustaining higher yield. In light chernozem soil region, maize yield significantly was correlated with the physico-chemical properties of soil within 20–30 cm layer. Of all the soil properties, soil structure and pH were the main factors that determined the yield. Sustainable soil feertility improvement was an important measure to achieve high yield.