RESPONSES OF ACIDIC SOIL AND MAIZE ( Zea mays L.) TO LIME AND VERMICOMPOST APPLICATION AT LALO ASABI DISTRICT, WESTERN ETHIOPIA

Abstract

Soil acidity is one of the major yield-limiting factor for crop production worldwide, particularly on highly weathered and leached tropical soils. Different reports have indicated that there is significant soil acidity coverage in Ethiopia. Particularly, in the western part of the country, soil acidity is a well-known problem limiting crop production and productivity. As part of the solution to such problem in soils, combined application of lime and VC on maize has not been investigated in the area, in which maize was one of the potential cereal crops in the area. Field experiment was conducted at Lalo Asabi district in western Wollega during 2019/20 cropping season to evaluate the responses of soil and maize to the combined application of lime and vermicompost (VC). The experimental treatments were five rates of lime (CaCO3) (0, 25, 50, 75, and 100% of lime requirement (LR)) and three levels of vermicompost (0, 2.5 and 5 t ha-1). The treatments were arranged in factorial combinations in randomized complete block design with three replications. One composite surface soil samples from a depth of (0-15 cm) were collected from the experimental field before commencement of the experiment. A total of fifteen composited soil samples were also collected from each plot and then composited by replication to obtain one representative sample per treatments for determination of selected soil physicochemical properties. Maize yield and yield components were measured following standard procedures. The soil analysis results revealed that soil pH increased from 5.1(strongly acidic) to 5.8 (moderately acidic) while exchangeable acidity decreased from 2.44 to 0.31 cmolc kg-1 under combined application of lime at 75% LR+2.5 t VC ha-1, which resulted in improvement of others selected soil physicochemical properties. Likewise, the main effects of lime and VC showed a significant effect (p<0.05) on the number of days to 50% tasseling and silking, ear height, number of cobs per plant, number of grains per cob, thousand grain weight, above ground biomass and harvest index of maize. However, days to 90% physiological maturity, plant height, cob length and grain yield of maize were significantly affected (p<0.05) by lime and VC interactions. Maximum grain yield (7.99 t ha-1) was obtained from the combined application of lime at 100% LR+5 t VC ha-1 followed by combined application of lime at 75% LR +2.5 t VC ha-1 (7.73 t ha-1) even though both being statistically at par whereas the lowest grain yield (2.97 t ha-1) was obtained from control plots. The results of economic analysis indicated that the combination of lime at 75% LR+2.5 t VC ha-1 showed marginal rate of return 2322.74% with the highest net benefit of 49980 Ethiopian Birr compared to other treatments. This study indicates combined use of lime and VC could ameliorate the adverse effect of soil acidity, and application of 75% LR+2.5 t VC ha-1 enhances grain yield and produces the highest net benefit of maize grown on acidic soil of Lalo Assabi district.