UBC Theses and Dissertations
The effect of season and shrub-grass combination on the fodder quality of three agroforestry plant species grown in Maseno, Western Kenya Mengich, Edward Kibet
An experiment to study the effect of season and shrub-grass combinations on the fodder quality of leucaena (Leucaena leucocephala), calliandra (Calliandra calothvrsus) and Napier grass (Pennisetum purpureum) was established at Maseno, western Kenya. The species were managed as hedgerows on field bunds in a randomized complete block design with seven treatments and four replications. Fresh and dry leafy biomass assessments, and sample collection were done at two-month harvesting intervals for 18 months. Percent dry matter was determined by oven-drying approximately 500 g of fresh samples at 60 °C for 48-72 hours. Dried samples were ground to pass a 1 mm sieve and analysed for N (used for crude protein estimation), P, Ca, K, Mg, Zn, Cu and ADF (acid detergent fibre). Statistical analysis was done using SAS 6.04 at ⍺=0.05 significance level. Napier grass was highest in fresh and dry biomass productivity. Biomass productivity, however, dropped significantly in the second year. Biomass productivity of shrubs was lower, but was maintained at similar levels throughout the study period. Leucaena was highest in crude protein, Ca and Cu, but lowest in Zn and ADF. Calliandra was highest in P, Zn and ADF, but was lowest in K and Mg. Napier grass was highest in K and Mg, but was lowest in crude protein, Ca, P and Cu. Except in the leucaena-Napier grass mixture, where differences were not significant, establishment in shrub-grass combinations caused significant increases in the biomass yields of Napier grass. Biomass yields of the woody perennials were either increased significantly or were not affected. Nutrient concentrations of the legume plants were not significantly changed by shrub-grass combinations. The same is true of the Napier grass for most nutrients except K and Mg. The former was increased significantly in combination with both legumes, while the latter was significantly reduced in combination with calliandra, but remained unchanged in combination with leucaena. Except for K content in Napier grass (r=0.750), biomass and nutrients were not significantly correlated with rainfall. Other correlations were not significant and varied with species and parameter. It is suggested that the presence of at least some rainfall in all months maintained a reasonable level of moisture in the soil, so that adverse effects caused by prolonged drought in other areas were not observed at Maseno. Napier grass is suitable for providing the basic ration, while trees and shrubs have a significant potential as high nutrient supplements to conventional animal feeds. These can conveniently be established as tree or shrub-grass combinations. Attempts to diversify the genetic base of fodder trees and shrubs should be made to overcome problems related to toxicity, poor digestibility and the occurrence of pests and diseases.
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