PHOSPHORUS RELEASE CAPACITY OF PHOSPHATE ROCK – ANIMAL MANURE COMPOST ON THE GROWTH OF LETTUCE AND SOIL CHEMICAL PROPERTIES.

ABSTRACT The experiments were conducted in 2013 cropping season at the University of Education Winneba, Faculty of Agriculture research field in Mampong Ashanti in the forest transitional zone of Ghana on the Bediase series (FAO/ UNESCO : Chromic Iuvisol) to evaluate the effectiveness of three livestock manures and soil in acidulating Togo rock phosphate to release phosphorus, assess phosphorus release capacity of phosphate rock – animal manure compost on the growth of lettuce and soil chemical properties. The composting materials used were: Togo Rock Phosphate, soil, poultry manure, cattle manure and pig manure. The treatments used were; sole composting material, RP + composting material 1:2, RP + composting material 1:3. A complete randomized design (CRD) with 3 replicates was used. The study established that composting phosphate rock with animal manure significantly released phosphorus. The peak of P release was observed on the 63rd day, with the highest release occurring in RP + PM 1:3. Best performance of P release between the treatment ratios were in the order 1:3 > 1:2 > sole materials. While best performance of P release between the composting materials were in the order poultry manure > pig manure > cattle manure >soil. It was established from the study that phosphocompost application significantly affected the growth and yield of lettuce and N, P and K uptake. Treatment RP + PM 1:3 gave significantly (p < 0.05) higher values throughout the growing period than the other amendments and the control in plant height, leaf length, leaf width, leaf area, plant weight and N.P and K uptake. However, all the amended soils were significantly (p < 0.05) better in influencing lettuce growth than the control. The application of the phosphocompost increased the soil organic matter content, available P, K, CEC, total N, soil pH, organic carbon, exchangeable bases (Ca, Mg, K, Na), percentage base saturation and decreased exchangeable acidity. It is concluded that composting rock phosphate with animal manure improved the P releasing ability of rock phosphate as well as leaf length and yield of lettuce. The fresh and dry weights of lettuce were also better in amended soil than control