Effect of lime and phosphorus fertilizer on acid soil properties and barley grain yield at Bedi in Western Ethiopia

Soil acidity associated with soil fertility problems are the main constraints hindering barley production in most highlands of Ethiopia. Field experiment was conducted to evaluate effects of lime and phosphorus (P) fertilizer application to acid soils on grain yield of barley and soil chemical properties during 2009 to 2013 cropping seasons at Bedi in Western Ethiopia. The experiment was laid out in randomized complete block design with three replications. Five levels of lime (0, 0.55, 1.1, 1.65 and 2.2 t/ha) and four levels of P (0, 10, 20, and 30 kg/ha) were combined in a complete factorial arrangement. Lime requirement of the soil was calculated based on its exchangeable acidity. The combined analysis over years showed significant improvement of barley grain yield and soil chemical properties due to the main and interaction effects of lime and phosphorus. Grain yield was progressively increased with incremental levels of lime and Phosphorus application. The highest yield was obtained from 2.2 t/ha lime application coupled with 30 kg/ha phosphorus fertilizer, but on par with 1.65 t/ha lime and 20 kg/ha phosphorus application. Grain yield is increased by 274.0% with 1.65 t/ha lime and 20 kg/ha Phosphorus application in the initial year compared with control; however, this yield increment declined over years and reached 99.5% after five years. This yield reduction after five years of lime application may indicate re-acidification of the soil which warrants re-liming. In this study, lime application was the major source of variation for soil chemical properties. Soil pH was sharply increased by liming with the highest value (5.9) and thereafter slightly declined to 5.3 over five years. Exchangeable acidity decreased significantly with increase in lime application to as low as 0.1 cmol/kg, while available P and exchangeable Ca2+ were noticeably improved. Hence, lime application at the rate of 1.65 t/ha coupled with 20 kg/ha Phosphorus fertilizer could sustainably enhance barley production on acid soils of Bedi and similar areas with likely re-liming of the soils, every five years. Key words: Acid soils, barely, lime application, phosphorus fertilizer, soil properties.