Lime Application to Two Acidic Upland Soils for Soybean Production in Champasak Province, Lao PDR

Abstract

Low yield of soybean in the Lao People’s Democratic Republic (Lao) have been reported, where soil acidity could be one of the limiting factors affecting crop growth. In Champasak province, Lao, the effect of lime application on soybean production was studied on two acid upland soils, which varied in their chemical and physical properties. The NuMaSS software predicted that lime was needed and that the soil at the Bachieng site needed more lime than the Hoythakoune site. The results illustrated that liming had beneficial effects on soybean. The highest grain yields of soybean at the Bachieng and Hoythakoune site were 2,206 and 2,102 kg ha^-1 compared with the control treatment, which yielded 1,462 and 962 kg ha^-1, respectively. The results of the study indicated that lime had a strong effect on increasing soil pH, from 4.4 to 5.3 and from 4.7 to 6.0 for the Bachieng and Hoythakoune sites, respectively). The appropriate liming rates for soybean production at the Bachieng and Hoythakoune sites were about 1,710 and 550 kg CaCO3 ha^-1, respectively. An economic dominance analysis indicated that the net return from liming was very high for both the Bachieng ($ 402 ha^-1) and Hoythakoune ($ 503 ha^-1) sites.