Effect of age of cutting on the productivity and forage quality of fourteen Sesbania accessions in western Tanzania

Effect of age of cutting on the production and forage nutritive value of 9 Sesbania sesban and 5 S. macrantha accessions was evaluated over 4 growing seasons. The sesbanias were established annually and harvested at 4, 5, 6, 7 and 8 months of growth to estimate forage yield. Wood yield and plant mortality were estimated at the 8-month harvest. The forage yields varied from 0.1-3.8 t/ha with the highest recorded from the 4- and 5-month harvests. Plant maturity resulted in leaf fall but also an increase in the contribution of pods to total edible forage. Wood production varied from 1.4-6.4 t/ha. The local S. sesban accession T1 was best overall in biomass production. The lowest plant mortality rate (range 0-35%) was recorded for S. macrantha Accessions 017 and SR22 that maintained less than 10% death rate throughout. Major differences were also recorded in the concentrations of N (2.64-3.24%), P (0.18-0.27%), K (1.23-1.83%), Ca (0.71-1.54%) and Mg (0.20-0.33%) between the accessions. Age of cutting had no effects on P (0.20-0.24%), K (1.37-1.47%) and Ca (1.14-1.18%) levels but N (3.42-2.58%) concentration decreased and Mg (0.21-0.28%) concentration increased with forage maturity. It was concluded that moisture stress limited the potential of sesbania as a source of forage in the dry season and that plant mortality limited its use as a longterm source of fodder.