Modelling and Mapping Available Phosphorus Level of Tokat Kazova Soils with Geostatistical Estimation and Simulation Methods

Abstract

Determining and mapping the variability of soil properties ensures planning, effective and sustainable management, and monitoring spatial and temporal variability in agricultural areas. The objectives of this study were to model and map available P level of soils using two different geostatistical methods and to interpret differences of results of two methods. Ordinary kriging (OK) and Sequential Gaussian Simulation (SGS) methods were used in mapping. This study was carried out in the Kazova (20,656 ha), largest plain in Tokat and one of the prominent production area of Turkey. Eight hundred soil samples were collected in two depths (0-30 cm and 30-60 cm). Mean available phosphorus of study area were 14.18 mg kg-1 in surface soil and 8.87 mg kg-1 in subsurface soil. Based on maps prepared with ordinary kriging 11.56% of surface soils of Kazova contained low available P, 82.16% and 6.28% of soil had sufficient and excessive available P levels, respectively. Maps of SGS method (mean of 10 simulations) showed that 9.98% of surface soils of Kazova had low available P level. While 86.27% of the surface soil contained sufficient available P and 3.75% of soils was classified as excessive. For the subsoil of Kazova (30-60cm), dissimilarities between two mapping methods were higher. Different level of available P and location of these levels in the maps prepared with these methods have a potential usage of decision-makers to plan amount of fertilizer and risk modeling.

Keywords

• available phosphorus
• geostatistics
• ordinary kriging
• yarayışlı fosfor
• jeoistatistik
• ordinary kriging
• ardışık gauss simulasyon
• değişkenlik