Development of seedling uprooting unit for system of rice intensification

Abstract

The present study was conducted to develop a seedling uprooting machine for System of Rice Intensification (SRI). System of Rice Intensification is a method developed in Madagascar in the early 1980’s, where, it has been shown that yields can be enhanced by suitably modifying certain management practices such as controlled supply of water, planting of younger seedlings and providing wider spacing. In this method 12 to 15 days old root washed seedlings are transplanted on the well puddled field. Only one younger seedling is transplanted per hill with row to row and hill to hill spacing of 25 cm. The preparation of seedlings for this method involves uprooting from nursery and washing the roots. This is done manually and no mechanical device for uprooting seedlings is available at present. In this circumstance, there is a need for the mechanization in the uprooting, washing and feeding the seedling to root washed transplanter. On this ground a seedling uprooting unit for system of rice intensification was developed and field tested. The seedling uprooting unit was consists of four major components namely bed cutting tool, conveyor unit, main frame and power unit. In order to cut the required thickness of soil bed, cutting tool was developed and fabricated with MS flat sheet of 2mm thickness. It consists of a rectangular base plate (25×30 cm) placed horizontally beneath the cutting blade. The cut seedling beds were conveyed through a slatted belt type conveyor having two adjacent roller chains inter linked with MS flat linkages giving overall belt width of 25 cm and 155 cm belt length. In order to drive the conveyor belt, a power unit from the existing vertical conveyor reaper was chosen. It consisted of 4 hp gasoline engine. According to the geometry of power unit a suitable frame was fabricated using MS angles (3×3 cm) to attach the cutting and conveying unit. The developed seedling uprooting unit was tested in the field to optimize the speed of operation and angle of cutting. Three levels of angle of blade viz., 20, 30 and 40 degrees and three levels of engine speed viz., 1000, 2000 and 3000 rpm were selected for the study. The thickness of bed, time of operation, wheel slip and plant damage were tested with respect to the above selected cutting angles and engine speeds. From the field observations it was found that cutting angle of 30° with engine speed of 2000 rpm was best for the effective seedling uprooting in terms of bed thickness, time of operation, wheel slip and plant damage. For this final prototype field performance characteristics like field capacity, field efficiency and fuel consumption were assessed. The theoretical field capacity was computed as 163.33 m2h-1 and field efficiency was found to be 81.2 per cent. The observed fuel consumption for the final prototype was in the range of 0.51 to 0.53 l.h-1. At the present wage rate of Rs 300 per day, the total cost for uprooting and washing of seedlings for cultivating an area of one hectare by manual method is about Rs 750. The total cost for uprooting and washing of seedlings for cultivating an area of one hectare by using machine is Rs 250. Hence a saving of Rs 500 can be expected by using the developed machine for preparing the seedlings required for cultivating one hectare.