Liming Effects on the Stability and Erodibility of Some Brazilian Oxisols

Abstract

AbstractThe effects of liming on the aggregate stability and erodibility of three Oxisols in Parana State, southern Brazil, were studied. Two soils from Londrina, one in a 10‐yr coffee (Coffea sp.) plantation (LC), and the other in a secondary mixed hardwood forest (LM), were compared with a third Oxisol from Cascavel, also under secondary mixed hardwood forest (CA), to give a range of surface organic‐C contents in the order CA > LM > LC. Lime was applied to replicated field plots at each site to neutralize 0, 25, 50, 100, 200, and 400% of total exchangeable acidity. Acid was also added to the Londrina soils to reduce initial soil pH to that of the Cascavel soil. Changes in aggregate stability, soil splash, and water erosion were measured. Lime application decreased the weight percentage of 2.0 to 4.0‐mm‐diam. aggregates and mean weight diameter (MWD) of aggregates in Cascavel soil, but had no effect on the other two soils. Liming decreased the apparent clay content of all three soils, and increased water‐dispersible clay on the LC soil. There were no significant effects of liming on soil splash, in part because of the high experimental variability of measurement. Soil erosion, measured on the field plots with a portable rainfall simulator, was in the order LC > LM > CA, a trend that corresponded to the decreasing organic‐C contents of the soils. Liming significantly decreased erosion on the LC soil, and had no effect on the other two soils. The study suggests that, while there may be some short‐term structural degradation caused by liming, the long‐term effect is to reduce water erosion.