WATER HYACINTH (EICHHORNIA-CRASSIPES) PRODUCTIVITY AND HARVESTING STUDIES

Water hyacinth growth rates were monitored from May through October in two sewage lagoons with different nutrient loading rates. The lagoon receiving the heaviest load sustained the highest average growth rates throughout the summer. The lightly loaded lagoon averaged a 29% increase in weight per week over the six month period with the highest growth rate occuring during June with an average weekly weight gain of 71%. The heavily loaded lagoon sustained an average growth rate of 46% per week for the same six month period with the highest measured growth rate of 73% increase in weight per week also occuring in June. In addition, the performance of three harvesters was evaluated. One harvester, consisting of a chopper and conveyor, was capable of picking up and chopping approximately 2.3 t of plants per hour and delivering them to a waiting truck. The second harvester was a single 1.52 m (5 ft) wide conveyor, and the third one was a modified clamshell bucket attached to a dragline. The average harvesting rate of each of these harvesters was approximately 9.3 t of water hyacinths per hour. © 1979 New York Botanical Garden, Bronx, NY 10458.