Comparative studies on minjingu phosphate rock and triple super phosphate as phosphorus sources in semi-arid lands of Central Tanzania
2000
Mkangwa, C.Z.(Sokoine Univerity of Agriculture, Soil Science Department, Morogoro, Tanzania)
Comparative studies on applications of Minjingu Phosphate Rock (MPR) and Triple Super Phosphate (TSP) as P sources were conducted in acid soils of Hombolo and Gairo located in Semi-Arid Lands of Central Tanzania. The objectives of these studies were to evaluate the possibilities of using MPR as a direct P source and to assess its residual effects on groundnut and maize grain yields. The experiments were conducted using a Randomized Complete Block Design replicated four times for five and six seasons for maize and groundnut, respectively. In the groundnut experiment six P treatments were compared. These included TSP applied at 6.6 kgPha-l, MPR applied at 6.6, 13.2, 26.4 and 52.8 kgPha-1 and 0 kgPha-1 as the control. TSP was used as a standard P fertilizer. For the maize experiment, the treatments were MPR or TSP at 13.2, 26.4, 39.6 and 52.8 kgPha-l, two combinations of MPR and TSP and 0 kgPha-1 as the control. The studies reported indicate that under adequate rainfall conditions, effectiveness of MPR and TSP were similar for groundnut and maize. Under such conditions MPR can be applied as a direct P source to groundnut and its residual effects can be expected in the second season after application. The data also suggest that groundnut can be produced without P application. In the case of maize, MPR is an effective direct P fertilizer like TSP but the residual effects of these two materials were not detected even one year after their application. However, due to inadequate rains received in most years, moisture appears to be the most limiting in these areas and thus any fertilizer use should consider this setback
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