Abstract:

Based on high-density sampling in the field, the spatial variability of soil pH and its influencing factors in cultivated land in Xi’an were analyzed by using the methods of geostatistics and GIS. The results showed that: (1) soil pH of cultivated land ranged from 5.8 to 8.9, with an average of pH 7.63±0.57. Meanwhile, coefficient of variation was 7.47%, which indicated a weak variability. (2) When ordinary Kriging interpolation was performed, soil pH was best fitted by the spherical model with no order trend effect, and the model nugget coefficient was 26.30%, showing a moderate spatial correlation. (3) Soil pH of cultivated land generally showed an increasing trend from south to north in the spatial distribution. The ratio of acidic soil, neutral soil, alkaline soil and highly alkaline soil were 1.47 %, 25.16%, 72.83% and 0.54%, respectively. In general, cultivated land soil in Xi’an was mainly alkaline and neutral soil. (4) The factors of soil parent material, soil type, soil texture, landform type, soil organic matter and elevation had significant impacts on spatial variability of soil pH. Altitude, soil type and soil parent material were able to independently explain 21.7%, 10.9% and 7.7% of soil pH spatial variability, and that far higher than other factors. So altitude, soil type and soil parent material could be used as the three main dominating factors for analyzing the spatial variability of soil pH in cultivated land in Xi’an. The research results could provide a reference for balanced fertilization management, cultivated land quality protection and upgrading regional ecological environment construction in Xi’an.

Key words: soil pH, spatial variability, influencing factors, geostatistics, GIS, Xi’an City