ИСТИНА

Electrical resistivity of cultivated sandy soils of humid areas is a complex characteristic based on three fundamental properties of soil matrix, such as soil texture, total organic matter (carbon content) and cation exchange capacity (CEC). Relationship of electrical resistivity (ER) with those properties has been approximated with exponential equation ER=a*exp(-b*x), where x is any of the properties above. The correlation coefficients for ER as function of CEC, texture, or organic matter were between 0.82 and 0.91 for the soils of Klin-Dmitrov watershed near Moscow and Kirov, which suggests their applicability for other humid areas. We present a new approach to approximate exponential relationship ER=a*exp(b*x) with a linear “piece-wise” function based on the age of cultivation for each field. This approach was used to develop management zones based on ER to separate uniform areas of similar organic matter, CEC and clay content. Those basic properties are the foundation of soil fertility in humid areas. They influence biomass and bioactivity of soil microorganisms, thus the exponential relationship between ER and soil microorganisms was also observed. The approach based of electrical resistivity or conductivity was used to evaluate fertility and degree of cultivation of sandy soils in humid areas and for detail soil mapping and delineation of management zones in adaptive precision agriculture. The field and laboratory electrical geophysical methods are recommended for quick and accurate soil mapping and management in sustainable farming.