EFFECTS OF LIME AND PHOSPHORUS LEVELS ON SELECTED SOIL CMEMICAL PROPERTIES AND BREAD WHEAT (Triticum aestivum L.) YIELD ON ACIDIC SOIL OF BANJA DISTRICT, NORTH WESTERN ETHIOPIA

Abstract

Soil acidity is one of the soil chemical degradation problems affecting soil productivity in the Ethiopian highlands. So, amendment of these soils is of paramount importance to enhance their productivity. This study was conducted during the 2017 cropping season to determine the effects of lime and phosphorus levels on selected soil properties and bread wheat yield on acidic soils of Pawe Agricultural Research Center Banja sub-station in Awi Zone of Amhara National Regional State. The experiment was laid out in randomized complete block design with three replications. Four levels of lime (0, 3, 4.5 and 6 t ha-1) and four levels of phosphorus (0, 10, 20, and 30 kg ha-1) were combined in a complete factorial arrangement. Lime requirement of the soil was calculated based on its exchangeable acidity. Soil samples were analyzed for Texture, BD, pH, total N, available P, OC, CEC, exchangeable Al and acidity, exchangeable base (Ca, Mg, K and Na). The grain and straw samples were also analyzed for concentration phosphorus. Wheat grain yield, thousand seed weight, biomass yield, number of tillers, plant height, spike length and number of seeds per plant were collected at recommended time. Then data were managed properly using the Excel computer software and subjected to the analysis of variance using the SAS software. Results of soil analysis after one month of liming showed that lime application significantly (p<0.05) increased soil pH (4.8 to 5.35), available P (12.15 to 15.42), CEC (33.71 to 35.28) and markedly reduced exchangeable acidity (3.08 to 0.44) and exchangeable Aluminum (2.62 to 0.27). A soil analysis results after harvesting of the crop indicated that, soil pH values (4.8 to 5.43) were sharply increased by increasing lime application rates whereas exchangeable acidity(3.59 to 0.40) and exchangeable Al3+ (2.95 to 0.27) highly decreased as the level of applied lime rates increased. However, mean of plant height, number of tillers per plant, spikes length, numbers of seed per plant, biomass yield and thousand seeds weight were progressively increased with incremental levels of lime application. Grain yield recorded from the application of 4.5 and 6 t ha-1 lime resulted in 84.7 and 96.6 % increment to the control and 11.7 and 18.9% increment to the 3t ha-1 lime. The main effect of P rate had significant (p<0.05) increase on plant height, biomass yield and thousand seeds weight and grain yield. Additions of 30 kg P ha-1 have also increased grain yield by about 12.9 % as compared to control (without P additions). Grain and straw P uptake was increased due to application of lime and P rates which were mainly associated with increased wheat yields. Moreover, the results showed significant improvement of wheat yield, plant P uptake and soil chemical properties (soil pH, available P, CEC and exchangeable acidity and Al3+) due to the main effects of lime and phosphorus. The optimum economic return (44,703.93ETB ha-1) was recorded from the combination of 4.5 t ha-1 lime and 30 kg ha-1 P.