Determination of physical, chemical and biological soil quality by SMAF method in pistachio vera cultivation areas

Determining soil quality in pistachio cultivation areas of Siirt is of critical importance for planning sustainable agricultural practices and enhancing both yield and product quality. In this context, the primary aim of this thesis study is to determine the physical, chemical, and biological soil quality of pistachio cultivation areas in Siirt province using the Soil Management Assessment Framework (SMAF) method. For this purpose, soil samples were collected from 115 different pistachio orchards at a depth of 0-20 cm. The physical, chemical, and biological properties of these soil samples were analyzed. Subsequently, each indicator was scored using linear and nonlinear scoring methods. Based on the scored indicators, physical, chemical, and biological soil quality indices were calculated. Additionally, considering these three indices, the overall soil quality index of the study area was determined. Furthermore, weighted indicator scores and quality indices were developed using the Analytical Hierarchy Process (AHP) method. The evaluations revealed that the physical, chemical, and biological soil quality scores in pistachio cultivation areas ranged from 0,46 to 0,86 (avg. 0,66), 0,46 to 0,95 (avg. 0,73), and 0,09 to 0,56 (avg. 0,30), respectively. It was observed that the Unweighted Soil Quality Index (SQI) ranged from 0,42 to 0,71 (avg. 0,56), while the Weighted Soil Quality Index (SQI-AHP) ranged from 0,38 to 0,73 (avg. 0,58). According to SQI-AHP scores, 1,7% of the study area had a very low-quality index, 27% had a low-quality index, 69% had a medium-quality index, and 2,3% had a high-quality index. The primary reason for the low SQI in the study area is attributed to the low biological soil quality index caused by excessive soil tillage, low moisture content, and low organic matter content. Specifically, 88% of the study area had a very low biological soil quality index, 10% had a low index, and 2% had a medium index.