Effects of field management on spatial variability of soil properties in the north west of Urmia Lake (original) (raw)

2017

Abstract

The objective of this study was to compare the spatial variability of physical and chemical parameters of the soil in orchard, crop, and bare land uses being adjacent to each other located in the north-west Lake Urmia. Soil sampling was done based on regular gridding in bare and orchard land uses in to dimensions of 300 × 300 m2 and in crop land use into dimensions of 200 × 60. The location of the points was recorded through the global positioning system (GPS). A total of 108 soil samples (36 samples per each land use) were taken from the terrain depth of 0 to 20 cm. Disturbed samples were ari dried in the laboratory in order to measure the soil propertie, including particle density (Dp), particle size distribution, permanent wilting point (PWP), organic carbon (OC), mean weight diameter of aggregates’(MWD), soil acidity (pH), electrical conductivity (EC), sodium adsorption ratio (SAR), CaCo3, bulk density (Db), saturated (θs) and, field capacity (FC) moisture content, The, and saturated hydraulic conductivity (Ks) uere measured in undisturbed soil samples . The soil measured parameters were transferred to the Geographic Information System software (GIS) environment to determine the geostatistical parameters and the spatial variation map of soil properties was prepared. The results showed that there were positive and significant correlation between MWD and organic carbon (r = 0. 675 **) and Ks (r = 675 **) and also, negative and significant correlation between MWD and sand (r = 0.328 **) and Db (r = 0. 472/0 **). The average of MWD in orchard, crop and arid land use was obtained 1.23, 0.83 and 0.48 mm, respectively. And also, the average of EC (extract 1 to 10) in orchard, crop and bare land use was obtained 0.33, 0.16, and 0.56 ds.m-1. The best model of spatial structure is gaussian model for OC in both crop and bare land use, for MWD and EC in the orchard land use, and for EC in bare land use and is spherical for MWD and EC in crop land use and is linear for MWD in arid land use and is exponential for OC in orchard land use. in orchard land use, EC and Dp had the highest (279 m) and lowest (57 m) impact range, respectively. In crop land use, AW and EC had the highest (282 m) and the lowest (23 m) impact range, respectively. In bare land use, pH and Dp had the highest (563 m) and lowest (110 m) impact range, respectively. The results of geostatistical analysis showed that most of the parameters have strong correlation in orchard and arid land use, moderate correlation in crop land use in the studied area. The results obtained from the evaluation of the interpolation methods showed that cokriging method was the best method for OC and EC parameters in orchard land and for MWD and EC in bare land use, the best method and kriging method was the best method for MWD in orchard land use and for MWD and OC in crop land use and for OC in bare land use, and IDW was the best method for EC in crop land use. Among the studied characteristics, saturation moisture content (144.2) in orchard land use, sand (15.2) in crop land use and soil porosity (49.62) in bare land use had the highest piece effect (C0) and SAR and soil acidity pH (0.0001) in orchard land use and the EC parameter (0.00001) in crop land use, and the parameters Dp and EC (0.00001) had the lowest piece impact among all measured parameters. The results showed that the physical and chemical quality of the soils in the lands affected by the salt of Lake Urmia in orchard and crop land use was higher than bare land use. Therefore, by selecting suitable management methods, the quality loss of the soils near the Lake Urmia can be partially prevented.

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