TEMPORAL CHANGES IN SOME SOIL CHEMICAL-PROPERTIES AT 4 DEPTHS FOLLOWING THE SURFACE APPLICATION OF LIME

The effect of a surface application of lime (5000 kg/ha initially then 2500 kg/ha 1 year later) on soil properties in four soil layers was m easured over 15 years on a yellow-grey earth (Duric Palic soil). The m aximum increase in soil pH occurred about 2 years after lime was initi ally applied in the 0-50 mm soil layer, after 5 years at 50-100 mm, af ter about 12 years at 100-150 mm, and was still increasing at 150-200 mm. The average rate at which soil pH increased until a maximum differ ence occurred was 0.57, 0.15, 0.04, and 0.009 pH units/year in the 0-5 0, 50-100, 100-150, and 150-200 mm soil layer, respectively. The avera ge rates of soil re-acidification (rate of decrease after reaching a m aximum) were 0.075 and 0.02 pH units/year in the 0-50 and 50-100 mm la yer, respectively. For exchangeable calcium (Ca), the average rate of decrease after reaching a maximum was 0.82 and 0.17 cmol(+) Ca/kg per year in the 0-50 and 50-100 mm soil layer, respectively. At this rate of decrease, lime should increase soil pH in the 0-50 mm layer until a bout 17 years after application. Lime significantly decreased exchange able magnesium (Mg) for only 5 years, with the maximum decrease betwee n 0 and 100 mm occurring about 3 years after lime was applied. Below 1 00 mm, exchangeable Mg was about 0.2 cmol(+)/kg lower in the lime trea tment from 5 years after lime was applied. Lime decreased Olsen P at a n average rate of 0.53 and 0.27 mu g/ml per year in the 0-50 and 50-10 0 mm layer, respectively up to 6 years after lime was applied. This de crease was partly attributable to higher plant phosphorus (P) uptake i n the lime treatment.