Spatial Variability Portrayal of Soil Fertility Indicators in Apple Growing Area of Ziarat Balochistan Using Geostatistical Analysis

Objectives: To assess the soil heterogenicity and mapping of spatial distribution of soil fertility indicators for efficient nutrient management in apple orchards using geostatistical tool. Methods: Soil samples were collected from 50 apple orchards in district Ziarat where 20 from Ziarat and 30 from Sanjavi tehsil. GPS locations were marked at each orchard. Four soil cores were dug below each of the 8 apple tree canopy and composited into one sample. The samples were air-dried, ground, sieved through 2 mm sieve and analyzed for soil texture, organic matter, pH, EC, macro (N, P and K) and micro (Cu, Fe, Mn and Zn) nutrients. Descriptive statistics was carried out using Microsoft Excel. Geostatistical analysis was conducted by ArcGIS 8.1. Findings: Texturally, soil of the apple orchards were grouped into silt loam, sandy loam and loam where silt loam was dominant class as 82% samples were silt loam. Soil was non-saline (0.42 dSm-1) and have pH in alkaline ranges (7.71-8.45) with average value of 7.93. Kjeldhal’s N, AB-DTPA extractable nutrients i.e. P, K, Cu, Fe, Mn, and Zn were in the range of 0.02-0.15%, 0.26-9.41, 21.0-203.60, 0.21-1.35, 0.25-6.29, 0.41-65.97 and 1.80-27.01 mgkg-1 respectively. Most of the orchards (54%) expressed soil organic matter in adequate range and 46% orchards\' soil showed medium level TN. Low level P, K and Fe was noted in 72, 50 and 74% orchards\' soil. The findings of geostatistical analysis showed that Soil pH, Cu and Mn had a weak spatial autocorrelation. While TN, and Zn had a medium whereas P, K and Fe had a higher spatial autocorrelation. Novelty: This research study provides procedural input for precise utilization of fertilizers as per soil properties of the area with minimum wastage and greater output. Keywords apple orchard, geostatistics, plant nutrients, soil properties, spatial variability