A thesis submitted in partial fulfillment of the requirement for the Degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1995

A walking type of a self-propelled azolla combine harvester was developed and tested for its field performance. The harvester is powered by a diesel engine (8.6 kw) of a Kubota two wheel tractor (Model NC131). It has two steel lugged wheels for improved traction. The harvester consists of a v-shaped float made of aluminum skids and side wall made of plastic net. The floats assist in collection of floating azolla fern which is pushed by a reel made- up of aluminum bats. The azolla mass is lifted by an inclined chain conveyor made of plastic net. The inclined conveyor delivers the azolla mass into an aluminum box which has a slat type conveyor at its bottom. This slat type conveyor carries the azolla mass to the rear end of the machine. The flow of azolla at the rear is controlled by a shutter mechanism and azolla mass is distributed across the width by a set of distributing blades. The effective field capacity of the machine is 853 kg of azolla per hour, while the machine is stationary at the edge of the field and azolla mass is pushed towards the machine by a flexible plastic tube. The effective field capacity of the mobile machine when harvesting azolla in 10-20 cm deep water was found to be 396 kg/h. The azolla mass was distributed by the machine at the average rate of 8 t/ha with 19% coefficient of variation. The cost of azolla nitrogen obtained by using the harvester was found to be 3.17 times cheaper than the cost of nitrogen from urea. Many developing countries may reduce the foreign exchange required to import chemical nitrogenous fertilizers, if they produce and apply azolla locally.