Effects of Bentonite on Sandy Soil Chemistry in a Long-Term Plot Experiment (II); Effect on pH, CEC, and Macro- and Micronutrients

Microplots (0.8 m(2)) were filled with a subsoil of a very poor, acidic sandy soil. This soil was enriched with bentonite (BNT) at rates of 0, 3, 6, and 12 kg/m(2). For 30 years the microplots were planted with different crops and regularly enriched with mineral and organic fertilizers. For the next eight years the microplots were left barren. After that time, the soils with added BNT had higher pH and content of available Mg than the control soil (CS) in the whole studied 5-80 cm soil profile. The soil with the highest dose of added BNT contained more total Ca, Mg, Zn, and Mn, as well as available P and K in 5-30 cm layer than the other soils. Furthermore, in comparison to CS, the soil with 12 kg/m(2) of BNT had higher cation exchange capacity (CEC).