Consequences of basic slag on soil pH, calcium and magnesium status in acid sulfate soils under various water contents

Consequences of Basic Slag (BS) on soil pH, Ca and Mg status in acid sulfate soils under various water contents were studied for 30 months. The four doses of BS at the rates of 0, 10, 20 and 30 t ha^-1 and three levels of water contents such as: (a) moisture at field capacity (50% water), (b) moisture at saturated condition (100% water) and (c) wetting-drying cycle (from saturation versus field capacity) were considered for this incubation study. Basic slag at 30 t ha^-1 was found to be the best dose in order of the increment in soil pH, followed by the lower doses of BS₂₀>BS₁₀. The BS₃₀ treatment increased the soil pH values by about 1.0, 1.5 and 1.2 units more compared with the control in the Sarisabari soil and 2.0, 1.7 and 1.5 units more in the Purbapukuria soil under the conditions of field capacity, saturated and wetting-drying cycle, respectively. Apart from the water contents and soil conditions, the values of soil pH were also increased significantly (p≤0.05) at different periods of incubation compared with the control. Like soil pH, almost similar to and significant (p≤0.05) increased levels of Ca and Mg were determined in both the soils; regardless of water contents and incubation time. The striking changes were recorded for the rate of increments of Ca and Mg, which were 4 to 5 times higher for Ca and more than 2 times higher for Mg compared with the control after 2 months of incubation. These results suggest that the application of basic slag not only increased the Ca to the higher amount than the increment of Mg in the soils but also improved one of the important criteria of imbalance between Ca and Mg status in the soils.