Increase in cation exchange capacity by the action of maize rhizosphere on Mg or Fe biotite-rich rocks

Abstract

The weathering of some silicate minerals in crushed rocks may occur in a few days of cropping and generate different physicochemical properties, with potential benefits to tropical soils. This study aimed to investigate the infuence of maize (Zea mays L.) rhizosphere on the weathering products and on the cation exchange capacity of Mg-biotite from biotite schist and Fe-biotite from biotite syenite. An experiment was carried out in pots, so that plants and crushed rock materials could be evaluated during seven successive growth cycles. The nutrients iron and potassium were taken up from biotite schist and biotite syenite during cropping. The weathering of both biotites promoted by the rhizosphere caused mineralogical changes. The most expressive change in the X-ray diffraction patterns occurred in the < 53 µm particle size fraction; however, the 53-300 µm fractions also changed. The alteration in the Mg-biotite, which has a lower Fe/Mg relation in octahedral sites than the Fe-biotite, was responsible for the most expressive cation exchange capacity increase in the fractions < 300 µm. However, the Fe-biotite weathering process, which presents a higher Fe/Mg relation in octahedral sites, did not increase the cation exchange capacity.

Growth of Urochloa grass in an oxisol treated with powdered silicate materials

“…The mineral biotite was found in the composition of both biotite schist and biotite syenite, as well as in vermiculite (Table 5). Although in lower proportions than the other minerals, biotite is the main mineral prone to release nutrients, such as K, Ca, Mg, Fe and Mn, as well as other elements, such as Al and Na, from biotite schist and biotite syenite, by weathering, during plant growth (Krahl, 2020). Even though, variations in the chemical composition of biotite, lead to differences in its weathering rates and, therefore, in the availability of elements to plants (Basak, 2018;Krahl, 2020).…”

“…Other important nutrient source for plant growth in basalt is andesine [(Ca,Na)(Al,Si)4O8], a plagioclase feldspar (Krahl et al, 2020). 257 --------------------------------------------------------------------weight % ------------------------------------------------------------------- (Paktunk, 1998); 2 Keys: Cp (clinopyroxene); Am (amphibole); Ad (andesine); Bt (biotite); Mu (muscovite); Ch (chlorite); Do (dolomite); Ab (albite); Kf (K-feldspar); Ap (apatite); Ky (kyanite); Qz (quartz); Mt (magnetite); Im (ilmenite); Hm (hematite); Vm (vermiculite); Sm (esmectite), Kt (kaolinite); 4 Source: Krahl (2020).…”