SOIL FERTILITY STATUS UNDER DIFFERENT LAND USE TYPE AND EFFECTS OF AMENDMENTS ON SELECTED SOIL PROPERTIES AND MAIZE (ZEA MAYS L.) YIELD IN ASSOSA DISTRICT, NORTH WESTERN ETHIOPIA

Abstract

n degraded and leached soils due to intensive cultivation, soil acidity problems and a decline in fertility comprise major limitations to soil productivity and crop yield. To overcome this problem, one survey and two experiments were conducted in laboratory, greenhouse, and field condition. The objective of this study were to assess soil fertility under different land use types, determine the effects of lime, NPSZnB, and vermicompost on selected soil chemical properties, and response of maize yield and selected soil properties to the application of amendments in field experiment. To assess soil fertility, samples were collected from three representative Kebeles under three land use types. For the incubation experiment, four levels of lime, four levels of VC, and four rates of NPSZnB fertilizers were used. For the field experiment, two lime rates, three vermicompost rates, and three blended fertilizer rates were used. The results indicate that cultivated land has relatively lower soil pH, organic carbon, total nitrogen, basic cations, CEC, available phosphorus, available sulfur, extractable Zn, and B, and relatively high bulk density, exchangeable acidity, extractable Mn and Fe when compared with grazing and forest land. The combination of different treatments improved soil pH, organic carbon, total nitrogen, available phosphorus and available sulfur, exchangeable bases, extractable zinc, and boron significantly over the control treatments. The two years field experiments recorded results indicate that significantly higher phenology maturity days, plant height, cob length, number of grains per cob, thousand seed weight, grain Yield, above ground dry biomass yield and harvest index were recorded in treatments that received integral application 4 tons ha-1 lime, 5 tons ha-1 vermicompost and 200 kg ha-1 NPSZnB inorganic blended fertilizer. The soil analysis after harvest revealed that amendments improved pH, organic matter, total nitrogen, exchangeable bases, and cation exchange capacity while exchangeable acidity significantly decreased. Integrated application of lime, vermicompost, and inorganic fertilizer can be recommended for ameliorating the acidity of the soils and overcome the current surface soil acidity and fertility decline problem and increasing maize yield to optimum production rather than solo application of organic or inorganic fertilizer.