Avaliação da capacidade máxima de adsorção de fósforo na fração argila de latossolos da região do triângulo mineiro

Abstract

Oxisols/latosols are soils characterized by an advanced weathering stage their composition influences the low availability of nutrients for this type of soil, which can limit productivity in these areas. To minimize this problem, the application of phosphate fertilizers may be necessary. Phosphate rock is the main raw material used in the production of fertilizers and its exploitation generates major negative environmental impacts. The rational use of phosphate fertilizers requires knowing the maximum phosphorus adsorption capacity for soils. Thus, this work aimed to evaluate the maximum phosphorus adsorption capacity (CMAP) of three classes of soils in the Triângulo Mineiro region, Dystrophic RedYellow Latosol (LVAd), Dystrophic Red Latosol (LVdf) and Eutropheric Red Latosol (LVef in the depths of 20 centimeters and in 1 meter, correlate the values with clay content of the soils and find the Zero Charge Point (PCZ). The concentration of phosphorus in the supernatant solution for the analysis of CMAP, was determined by the colorimetric method and the adsorbed phosphorus values were submitted to the Langmuir isotherm adjustment. The results showed that the CMAP values in the three soil classes ranged from 43.77 (LVdf 20 cm) to 132.16 mg hg1 (LVAd 1 m). The clay content found classified LVAd and LVef as very clayey soils and LVdf as sandy clay. The comparison between CMAP and clay content resulted in an adequate linear regression adjustment with a determination coefficient of 0.89. The Zero Load Point (PCZ) indicates the pH at which the load balance in the soil colloids is zero, and the values of the studied soils varied between 3.23 and 4.26. With the results found in this work it is concluded that the CMAP values are related to the clay content of the soils, with the organic matter and with the pH, showing the importance of studying these parameters when using techniques to decrease adsorption phosphorus in the soil and increase its availability for plant absorption.