Analysis of the Soil Selective Potassium Content, using Multifrequency EC Sensors

Abstract

The relative salinity of soil is an important issue in today’s sustainable, site-specific Precision Agricultural practice. The need to replace salt has an enormous impact on production costs, regarding current input prices. The standard method for measuring the salinity of a soil, based on a laboratory test method, is expensive and cumbersome and only the total salinity content can be determined. Growers need to get data faster and cheaper. With the usage of on-the-go soil sensors, this process can be significantly improved. This article presents the first step of developing a quick, cost-saving and easy-to-use measurement method for determining the selective potassium content on the spot, in real time. In our work, we developed a new measurement and calculation method using the analytical application of multifrequency conductometry, to determine selective salinity. It is proved that the electrical conductivity (EC) develops according to different functions, by applying solutions containing K+ ions with a defined concentration, by saturating the soil with a continuously, but reasonably varying measuring frequency. Based on this recognition, the selective salinity of soil can only be determined by interpolation from a frequency-series of EC measurements, in soils containing only one electrolyte.