Spatial variability of vertisols nutrients in the Deccan plateau region of north Karnataka, India

Abstract

The status of soil fertility is a concern, especially in the Deccan plateau vertisols of India. Vertisols are productive if they are managed well. Understanding the spatial variability of soil macronutrients is necessary for agriculture to maintain sustainability. The objective of the present study was to explore the spatial variability of macronutrients [available nitrogen (N), available potassium (K), and available phosphorus (P)], soil pH, and electrical conductivity (EC), in scattered small-size fields of northern Karnataka, India. This region is known as the “pigeon pea vessel” of the state. The sixty-eight random topsoil samples were collected from marginal farms, which are less than two acres in size in the study region. The geostatistical analysis is carried out in SpaceStat 4.0® to find the spatial variability of macronutrients, soil pH, and EC. The coefficient of variation monitors the variation in the nutrients of the soil. The variogram analysis has shown K, soil pH, and EC are best fit to spherical model, N and P for an exponential model. According to the ratio of nugget/sill, it indicates they are moderate spatial dependent, excluding N. Using the best fit model, surface maps are generated using ordinary kriging method. The kriged maps exhibited a heterogeneous pattern of macronutrients because of separate farming methods. The spatial variability maps are used as initial regulation by policymakers for site nutrient management, including fertilization in vertisols. This is essential for sustainable and precise management of the fields, which are aimed at increasing the productivity of the crops; low productivity vertisols must be used in cultivation on a global scale due to current shortage of food supplies and agricultural resources land.