ASSESSMENT OF PRODUCTION SERVICE CAPACITY BY SOIL QUALITY EVALUATIONS

Abstract

The ability of a soil to provide the productivity service depends on the fulfillment of the functions that enable the realization of productivity service (PS). This study was conducted to determine and map the PS capacity of surface and subsurface soils in a 195-ha farmland located at Amasya province of Turkey. Functions that contribute to the provision of PS have been identified, and effective indicators ensuring the realization of functions have been identified. Indicator values were converted to unitless scores using non-linear scoring functions defined in soil management assessment framework. Simple additive (SA) and weighted additive (WA) methods were used to calculate soil functions scores and PS index values. The weights representing the contribution ratio of each indicator to soil functions as well as each function to PS index were obtained by employing the Analytical Hierarchy Process (AHP). Soil functions scores were calculated by summing of the weighted indicator scores, and the PS index value was obtained by summing the weighted function scores. Ordinary kriging, inverse distance weighting and radial basis function methods were used to produce maps for functions and PS index values. Root mean squared error and mean absolute error values were used as criteria to determine the most accurate interpolation method. The AHP technique revealed that nutrient cycle function had the highest (34%) contribution to the provision of PS, while the durability and resistance function (15%) had the lowest contribution. The PS index value was calculated as 0.57 and 0.59 by SA and WA methods, respectively. The PS index values and soil functions, except the resistance and resilience, calculated both by SA and WA were slightly different for surface and sub-surface soils. The results revealed that organic carbon is the most influential indicator affecting the soil functions and consequently the PS of soils.