An experiment on the effect of dolomite was carried out at Khon Kaen University, Khon Kaen, Thailand to investigate the response on growth and seed yield of soybeans. Three levels of dolomite being used were 0, 937, and 1,875 kg/ha and five soybean cultivars were SJ4, SJ5, Chiang Mai60, KKU1, and KKU2. The experiment was laid in a factorial with four replications.
The results showed that the application of dolomite significantly increased pH of Oxic Paleustult soil, shoot growth, stem plus petiole dry weights, leaf dry weights, and leaf areas of the soybean plants but had no effects on seed size and seed yield/ha. Seed yields of the soybean plants were highest with KKU1 followed by KKU2, SJ5, SJ4, and Chiang Mai60, 3,823, 3,324, 3,283, 3,210 and 3,123 kg/ha, respectively. There was some small relationships between seed yield and total shoot dry weights and also between seed yield and leaf areas. Leaf area indices of the soybean plants reached the value of 5. Seed yield was affected by inadequate amount of soil moisture content. Oxic Paleustult soil always requires at least 937 kg/ha of dolomite for good crop yield. It was suggested that dolomite is always needed for most tropical acid soils.