Effects of Phosphorus Sources and Application Rates on Nitrogen and Phosphorus Concentrations and Phosphorus Use Efficiency in Rice Plant

A study was conducted to determine the effects of nitrogen (N) and phosphorus (P) concentrations and P use efficiency from Minjingu phosphate rock (MPR), Minjingu mazao and Triple Super Phosphate (TSP) fertilizers under irrigated rice (Oryza sativa L.) production in Lekitatu village, Meru district, Arusha region, Tanzania. The initial soil pH in the two experimental sites was slightly alkaline while total N and available P was low and medium respectively. Randomized Complete Block Design (RCBD) with three replications was adopted and phosphorus was applied at the rates of 0, 20, 40 and 60 kg P ha-1 as MPR, Minjingu mazao and TSP. Nitrogen was applied uniformly at a rate of 60 kg N ha-1 as urea taking into account the 10% N contained in the Minjingu mazao fertilizer. Phosphorus application increased N and P contents in the rice plants and phosphorus use efficiency (PUE) with the increase of P levels from 0 to 60 kg P ha-1 for all P sources. The site 1 had more PUE than site 2 due to higher moisture content. These effects were due to increased availability and nutrients uptake by plants, particularly P. Based on the results, it is recommended that; Minjingu mazao at the rates of 40 to 60 kg P ha-1, MPR and TSP at a rate of 60 kg P ha-1, respectively have to be adopted for sustainable soil P use in rice production areas of Lekitatu village.