International Agrophysics Vol. 3. No. 3. 1987 [antikvár]

International Agrophysics 3 (3)rpp. 93-Í02 {Í987)RELATIONSHIP BETWEEN PHOSPHATE- AND POTASSIUM DESORPTION AND CLAY MINERAL COMPOSITION OF SOILSP. STEFANOVITS1, GY. FÜLEKY1 and I. JÁKI21 University of Agricultural Sciences, Gödöllő, H-2103, P.O. Box 303, Hungary 2 Laboratory for Plánt Protection and Agrochemistry, Kaposvár, H7400, Hungary(Received 15 May 1986)Curves of phosphate and potassium determined by electro-ultra-filtration and continuous fractionation as weli a knowledge of ciay mineral composition of soils provide information about the sorption and release of these two nutrients. In smectite soils, solutions containing ammónium ions cause a change in the sorbent itself and this is responsible for the interaction between nitrogén and potassium fertilizers.Keywords: phosphate adsorption, potassium adsorption, soil clay minerals.IntroductionThe adsorption of phosphorus and potassium plays a great role in the mobilization of available plánt nutrients, and in the effectiveness of fertilizers. The characteristics and the degree of adsorption depend on the quality and quantity of soil colloids [10]. The quality and quantity of mineral colloids, clay minerals, are mainly responsible for adsorption because these components together with humic substances determine the processes of adsorption and desorption in soils.The clay mineral composition of Hungárián soils is known [7, 8] and is taken into account in the fertilizer advisory system, however, a knowledge of the causai relations would provide support in this respect. The method of electro-ultra-filtration (EUF) is widely used as well, so the theoretical foundations for the estimation of data may contribute to the better usage of EUF curves [1,2, 4].The method of continuously fractionated desorption (FD), as a result of the further development of sorption studies [6], is more appreciable if the role of colloids in the adsorption process is properly known [3].Materials and methodsThe 9 soil samples are from the ploughed layer of soils which are characteristic for large regions of the country, and are different in respect of clay mineral associations. The analytical data of soils are shown in Tables 1, 2 and 3.Before investigating the sorption and mobilization of phosphate and potassium, a part of the samples was treated with fertilizer. The data of the fertilizers used are shownAkadémiai Kiadó, Budapest Martinus Nijhoff/Dr. W. Junk Publishers