Effects of liming and gypsum regimes on chemical characteristics of an acid forest soil and its leachates

A dystric cambisol (acid brown soil) with an acid mull humus consisting of Of, Al and (B) horizons was used to study changes in soil and leashate chemistry. The natural soil was reconstituted in columns equipped with zero tension lysimeters. CaCO3 CaCO3+MgO and CaSO4 treatments were added at rates equivalent to 0.56, 2.8 and 5.6 t ha(-1) of CaO. Soil pH and exchangeable cations were determined before treatments were applied, and at the end of the 20 month experimental period. Leachates from the columns were analyzed for pH, S, Ca, Mg, Al, K, N-NO3 and N-NH4 at monthly intervals throughout the 20 month period. Liming provoked the greatest increase in the soil pH values. This was limited to the Al horizon when using the lowest rate but was also observed in (B) horizon after application of 2.8 and 5.6 t ha(-1). Exchangeable calcium values were higher in the upper 6 cm but decreased rapidly in the deeper layers. When gypsum was added, the pH increased signif icantly but this was restricted to the humus and Al horizons; exchangeable calcium was increased significantly down to the (B) horizon. Aluminium saturation decreased in the layers with high exchange able calcium and higher pH values. For base saturation, patterns similar to calcium were observed throughout the profile. Leachates were enriched with basic cations which increased the pH, especially when the high liming rate was applied and also with the 2.8 and 5.6 t CaO ha(-1) rates of gypsum. Nitrogen was leached mostly as N-N-3, in the lime treatments and in the control, whereas nitrification was inhibited in the gypsum treatment and nitrogen was predominantly in N-NH4 form.