Effectof Sokoto Rock Phosphate and Single Super Phosphate in Cassava-Based Cropping Systems.

ABSTRACT

       Cassava yield is usually affected by low soil phosphorus, particularly in acid sandy soils. Although there are local sources of phosphorus such as directly mined rock phosphate, there is paucity of information on how these local P sources affect the growth and yield of cassava. A mined product called Sokoto Rock Phosphate (SRP) was evaluated as a potential substitute for the commercially available Single Super Phosphate (SSP) which is expensive and often inaccessible to local farmers.

             Trials were conducted in Benin City, Nigeria, to evaluate SRP and SSP in a field experiment with randomized complete block design, replicated three times.  In the first trial, the effects of SRP on cassava /maize, cassava/cowpea and sole cassava systems and P utilization were investigated. The effects of SSP on P utilization of the same cropping systems were tested in the second experiment. Leaves, stems and root samples were collected at 3, 6 and 9 months after planting (MAP) for nutrient uptake and  yields.

          Highest yield of 38.3 t/ha fresh tuber of cassava was obtained with an application rate of 45 kg SRP/ha in sole cassava cropping system, which was significantly higher than all levels of the P sources and cropping systems. Soil available P in cassava/maize cropping system at 45 kg SRP/ha rate was significantly higher (8.81 mg/kg) compared to other treatments and pre-planting soil P with a value of 1.63 mg/kg. Phosphorus uptake was significantly higher (0.92 g/plant) when 45 kg SRP/ha was applied in the cassava/cowpea cropping system when compared to all treatments at 3 MAP.

          The yield of cassava in the three cropping system was significantly improved with the application of SRP at 45 kg/ha and applying SRP at this rate could substitute for P fertilizer in the cropping systems investigated, particularly in acid sandy soils of Benin area.