MSc

Grow bag cultivation is getting popular in our state due to urbanisation. It necessitated easy method of filling grow bags as per the favourable agronomic conditions for crop growth. A grow bag filling machine was hence developed and tested for filling grow bags of different size. The machine was developed by modifying the KAU manure pulverizer by suitably fixing a collecting hopper beneath the sieve, grow bag holders attached to one leg of the stand for holding different bags and pedal for controlling the filling. The machine consists of an electric motor, a feeding chute, pulverizing drum, transmission unit, rotating blades, sieve and a supporting stand. Materials were pulverized and mixed due to rotations of the blade which caused the cutting and shearing actions and got pulverized in the clearance between the blade and the sieve. The grow bag mixture was discharged through the sieve and got collected in the bottom hopper. A pedal operated valve was inserted into the small hopper to facilitate metered discharge of the potting media. As and when it is allowed to open a metered quantity of the mixture was discharged into the grow bags placed below it.
The machine was tested to determine its performance and to optimize the machine parameters and material parameters at different moisture contents of 10,15,20,25 and 30 percent, clearances of 15, 20 and 25 mm, two ratios of soil: coir pith: FYM as 1:1:1 and 1:0.5:1 mixture and for three bag sizes of small medium and large. Dried soil, coir pith and FYM get pulverized, mixed and filled in the grow bags. The properties of grow bag mixtures obtained were found out and were on par with the ideal recommendations. The properties such as water holding capacity (165.02 percent), bulk density (0.493 g.cm-3), porosity (65.43 percent), fineness modulus (5.31), angle of repose (46.66º), pH (6.76), electrical conductivity (2.19 dS.m-1) and uniformity of mixture were observed at the ratio 1:1:1 (S:C:FYM) at the moisture content of 15 percent. Performance parameters such as weight of bags filled (6.18 kg) time of operation (230 s), capacity of the machine (385 kg.h-1), number of bags filled (63) and energy consumption (0.31 kWh for four bags) were obtained with an overall efficiency of 97.70 percent.
The cost of grow bag filling machine is Rs.49500. The hourly cost of operation for the machine is calculated as Rs.357. The analysis of the results indicated that the performance of the machine was optimum for filling large grow bags at 15 percent moisture content at the ratio S: C: FYM as 1:1:1 for all clearances.