Effects of compost and lime amendment on soil acidity and N availability in acid sulfate soil

摘要

The aims of this study were to investigate changes in soil acidity, exchangeable and dissolved aluminum (Al) and N availability after application of lime and/or compost. In the Mekong delta, field experiments were established on severely acid sulfatesoil recently cultivated with Momordica cochichiensi. Before planting, soil samples were taken at 0-20 cm depth for incubation experiments. The results from our field experiments showed that applying 5 kg compost per plant in addition to a basal application of 37.5 g N, 220 g P_2O_5 and 85 g K_2O per plant led to an increase in soil pH and a decrease soil exchangeable Al~(3+) (P < 0.05). In incubation experiments, lime (CaCO_3) was added at rates of 80 and 202.5 mg/20 g soil, based on the results from lime requirement tests to reach desired pH values. In addition, compost was added solely or in combination with lime at an amount of 1.25 g. The results showed that application of lime at a rate of 80 mg CaCO_3/20 g soil in combination with 1.25 g compostincreased soil pH from 3.13 to 6.07. This combination also significantly decreased soil exchangeable and dissolved Al and increased soil content of NH_4~+-N. Application of compost alone or in combination of liming enriched soil with both NH_4~+-N and NO_3~--N. A significant increase in soil N03'-N after amending acid sulfate soil with compost only, may suggest that compost may be a source of nitrifying microorganisms.