Soil test phosphorus calibration for malting barley (Hordeum vulgare L.) production on Nitisols of Ethiopian highlands. (177)
Keywords:Nitisol, phosphorus calibration, phosphorus critical concentration, phosphorus requirement factor
AbstractDelivery of suitable fertilizer recommendations to smallholder farmers is becoming increasingly important, for reasons of food security, economic sustainability and the need to maintain soil fertility. Phosphorus fertilizer trials with malting barley were conducted on Nitisols of selected sites in West Shewa, Ethiopia during the 2009 and 2011 cropping seasons. The treatments consisting of six levels of phosphorus (0, 10, 20, 30, 40 and 50 kg ha-1) were arranged in a randomized complete block design with three replications. Results showed that yield and yield components of malting barley were significantly affected by P fertilization. The application of phosphorus fertilizer at different rates increased grain yields of malting barley by 28-47 % compared to the control. Available soil P concentrations extracted three weeks after planting significantly responded to P fertilizer rate. Correlation of relative yields with Bray-2 soil test phosphorus values showed that the soil test phosphorus levels greater than 12 mg kg-1 (critical phosphorus concentration) was found to be sufficient for malting barley production. The average phosphorus requirement factor (Pf), calculated from soil test phosphorus values of all treatments for the study area was 7.2. To protect a potential loss of malting barley yield, at least a maintenance application of 10 kg P ha-1 is needed for responsive sites that had soil test phosphorus levels above the critical level.