Phosphorus Levels and In-situ Processing Coefficients of Selected Allochthonous Forage Detritus in River Nyangores, Bomet County,Kenya

Abstract

Determination of the processing coefficients of allochthonous detritus is important as it gives critical information on: how much dissolved oxygen is used, the rate at which food nutrients are distributed downstream and environmental monitoring of aquatic ecosystem health. This study win involve the determination of the processing coefficients of . allochthonous detritus for three major forage plants, Elephant grass (Pennisetum purpereum), Coloured guinea grass (Panicum coloratum var. coloratum) and Boma Rhodes grass (Chloris gayana), which are commonly cultivated for livestock feed and to control soil erosion on the riparian zone and catchment of River Nyangores in Bomet County. The aim of the study is to determine the processing coefficients and its correlation with the level of phosphorus in the detritus of the three selected species. The study will be carried out in 5 months (September 2013 to January 2014). The objectives of the study will be: (1) To determine the processing coefficients of allocthonous forage detritus of boma rhodes grass, coloured guinea grass and elephant grass forage species cultivated in the riparian zones along a section of River Nyangores, (2) To provide appropriate in-situ aquatic breakdown categorization for the detritus of boma rhodes grass, coloured guinea grass and elephant grass, and (3) To determine the scientific correlation between the processing coefficients of the selected species and their dry matter phosphorus contents. A composite sample of senesced leaves of the selected species from forage farms 1-2 years old will be collected Quadrats will be used in the random sampling of the detritus. The composite samples for each of the species will be dried in the sun for 5-8 days in wooden boxes fitted with plastic screens to constant mass. Leaf packs (30 packs per species for deployment plus one pack for handling mass loss adjustment) weighed at 109 will be prepared. The leaf packs will be deployed in a suitable strategic site downstream ofBomet town. Six packs will be withdrawn at 2, 4, 6, 8 and 10 weeks intervals. The packs will then be rinsed with deionized water, processed and analyzed for ash free dry matter. The processing coefficients will then be calculated from a regression breakdown model for each species. The phosphorus and carbon content of the grass species will be determined using Elemental Analyzer before deployment, with additional phosphorus content determined at the last withdrawal. Data presentation will take the form of tables, charts and graphs produced using Excel computer program. The expected research output will be used by forage farmers, environmental monitoring systems developers, water resource scientists and aquatic ecologists. Key words: Processing coefficients, allochthonous detritus. ii