Characterization, classification and agricultural usage of vertisols developed on neogen aged calcareous marl parent materials

Abstract

Vertisols that strongly influenced by argillipedoturbation, contain high levels of plant nutrients and well productive when irrigated. However, owing to their high clay content, they are not well suited to cultivation without painstaking management. The aim of this research was to determine physical, chemical and morphological properties and classification of the Vertisols formed on neogene clay lime deposits under intensive agricultural actives in the Bursa province which is the fourth most industrialized and populated city in Turkey. Vertisols comprise 23.693 hectares or 2,1 percent of the land area of Bursa Province. Most of the Vertisols are under the rain-fed agriculture practices and cereals (wheat and barley), tobaccos, and sunflowers are the most important cash crops. Some of them are irrigated for horticultural crops (tomato, pepper and onion) and sugar beets production. According to findings from preliminary field-works and the existing maps and reports, eleven different soil profiles formed on the neogene aged calcareous marl parent materials were described and sampled. All studied Vertisols are found to be generally deep, dark colored with strong wedge-shaped structure, high in CEC and base saturation with calcium and magnesium occupying more than 90 percent of the exchange site, low organic material and have sufficient amounts of nutrients for crops. The agricultural potential of the soils were also found to be limited due to high clay and CaCO3 contents of sub surface horizons, steep slopes and a hard pan formation due to inappropriate soil tilling. On the basis of morphological and physicochemical analysis, soil profiles were classified as a Typic and Chromic Haploxerert according to Soil Taxonomy (Soil Survey Staff, 1975 and 1999) and as an Eutric Vertisol according to FAO/Unesco Soil Map of the World Legend (FAO/Unesco, 1974 and 1990) classification systems.