Mzee, Omari2025-10-082025-10-082001https://www.suaire.sua.ac.tz/handle/123456789/7100DissertationThis study was done to assess the effectiveness of Minjingu phosphate rock as a source of phosphorus for lowland rice production in selected soils of Tanzania. The study included soils from five sites for pot experiment and one of those sites was also used for a field experiment. Treatments tested were two sources of P namely MPR and TSP each applied at rales of 0, 40 and 160 mg P/kg, and 0, 20 and 60 kg P/ha under pot and field experiments, respectively. In both pot and field experiments, hosphorus released from all the treatments subsequent to flooding was determined by the Pi method and compared with P uptake, dry matter and grain yields of rice (Variety Kahogo-red). The relative agronomic effectiveness (RAE) of MPR relative to TSP was also determined. In the pot experiment, P application at high rate significantly increased drymatter yields by 33% to 498% relative to control. The performances of MPR and TSP were comparable in four soils (Lupilo, Ruvu-A, Ruvu-B and Kimani) whereas TSP did better than MPR in Michenga soil. Minjingu PR and TSP (high P application) were also comparable in improving P contents of plants. The RAE of MPR was high in Lupilo (95%), Michenga (82%), Ruvu-A (80) and Kimani (100%) soils while in Ruvu-B soil (68%) RAE was low. Extractable P after four weeks of flooding increased by 12 to 145% in four soils (Lupilo, Michenga, Ruvu-A and Kimani). In a field trial at Kimani, phosphorus application gave a nonsignificant increase in grain yield over the control and this was attributed to an appreciable increase in available P (from 5.14 to 10.10 mg/kg) after 42 days of flooding. Crop P concentration and uptake increased with application rates but the P sources (MPR and TSP) had comparable effects. Application of P did not increaseiii extractable P significantly. It is therefore concluded that MPR has the potential to supply P for rice production in Lupilo, Michenga, Ruvu-A and Kimani soils and others with similar properties.en-USRice ecosystemsPhosphate rockMinjingu phosphate rockLowland rice productionThesis