Spatio-temporal variability in physical properties of different textured soils under similar management and semi-arid climatic conditions

摘要

Soil physical properties play an important role in determining soil's suitability for agricultural uses. The purpose of our study was to characterize spatio-temporal variations in moisture content (theta(m)), bulk density (rho(b)), aggregate stability (AS) and penetration resistance (PR) of different textured soils under similar management and climatic conditions. A 25 x 25 m area was monitored in each of the 3 fields with Daphan clay (Haplustert), Ciftlik loam (Fluvaquent), and Ciftlik sandy loam (Ustorthent) from September 2014 to August 2015. Each area was divided into 5 x 5 m cells. Undisturbed soils from 0 to 10 cm depth at 36 intersection points were collected monthly, and processed and analyzed. Results showed that spatio-temporal changes in soil properties were strongly affected by natural freezing-thawing and wetting-drying processes. While the theta(m) increased with rainfall and/or snow melts through September January, the theta(m) decreased onwards February. The theta(m) ranged between 11.50 and 56.34% for the Daphan clay, 7.26 and 41.92% for the Ciftlik loam, and 2.52 and 33.83% for the Ciftlik sandy loam, with highest variabilities in January and November, and the lowest variabilities in July and August. The decrease in theta(m) was closely and linearly associated (r = -0.94**) with rho(b) and vice versa. However, the temporal variation in AS was primarily due to theta(m) and its effects on freezing-thawing and swelling/shrinking during wetting-drying cycles. While the lowest AS was measured in February, the highest AS was observed in July for the Daphan clay, and August for the Ciftlik loam and Ciftlik sandy loam, respectively. The AS linearly and inversely related to theta(m) (r = -0.66**). Likewise, the PR decreased linearly with an increase in theta(m) and vice versa. While the theta(m) linearly decreased the PR (r = -0.45**), the rho(b) increased PR (r = -0.45**). Results suggested that spatio-temporal variations in core soil physical properties could provide useful information for site-specific precision agricultural management practices to improve soil quality.