About Poly-bag Filler

Poly-bag filler is equipment used for filling potting mixture on polythene bags, in which plantlets are planted and can be ported to other locations where it can be transplanted.

Potting mixture is a mixture of soil, sand, organic manure etc ideal for the growth of plantlets. The soil will be packed loose in order to support easy development of roots.

Thickness of a polythene bag varies from 50 microns to 150 microns, usually takes circular shape and supports itself when filled with soil. Polythene bags come in different lengths and sizes depending on the purpose. Size varies from 2” to 8”. Length varies from 2.5” to 18”. For designing the machine, the above mentioned specifications are taken into account.

Commonly the process of poly-bag filling is done by hand. In most cases, the workers don’t use any kind of hand tools for filling bags.

Available Technology

The first prototype was developed by a farmer. It is essentially a funnel attached to a vertical column with a base as shown in figure below.


First prototype of poly-bag filling device

Operating with first prototype of poly-bag filling device

One person holds the polythene bag against the mouth of the device, and another person pours the soil though the funnel. Due to the shape of the funnel, the soil falls precisely on the bag.

Issues observed:

  • Minimum of 2 persons is required for operation. One for holding the bag, and other one for pouring the soil.
  • Difficulty in filling bags of smaller sizes. Mouth of the bag is about 3 inches in diameter. Hence it was inappropriate for filling bags of smaller sizes.
  • Difficulty in supporting the smaller bags while filling. Although a table or base is provided for supporting the weight, it was found inappropriate to support bages of smaller sizes.
  • Difficulty in flow control. Flow control can be exercised only in feeding end. The person pouring the soil must exercise complete control of the soil flow. Hence there is chance of increased drudgery for the worker.

Second Prototype

An effort was made by CORE support team of Mitraniketan to introduce new prototype of poly-bag filler by eliminating the issues observed in previous prototype.



Second Prototype developed by CORE Support team of Mitraniketan.

The following improvements were made in the new prototype.

  • Introduced valve mechanism for controlling the flow of soil mixture.
  • The funnel type structure in previous prototype was converted to a hopper of capacity about 1 Cubic Feet. This facilitated reduction in frequency of refilling the equipment.
  • Height of the equipment was optimized in order to fit women workers also.

Despite of the above mentioned features, following issues were observed in prototype testing.

  • Soil blockade due to the presence bend in outlet & rapidly reducing throat area.
  • Difficulty in operating the valve mechanism, which is caused by the increased frictional area in valve mechanism.
  • Second prototype was still unfit with bags of smaller diameters.



New Prototype

The third prototype was developed by eliminating the issues observed in the previous prototypes. The technical specification of the new prototype is listed below:

Dimensions (LxBxH) 460x460x1000 mm
Weight of equipment (without mixture) 13.5 Kg
Reserve Capacity 0.8 CuFt (25 Kg of mixture approximately)
Estimated cost ` Rs.5000/-
Materials used for fabrication Frame- MS Square Tube

Hopper – GI Sheet

Reducer – PVC

Handle – Wood


Hopper: Hopper is replaceable & has a capacity of 0.8 Ft3 (0.03 m3) which can hold up to 25Kg of potting mixture. Up to 20 bags (3” x 10”) can be filled before reloading the hopper. 

Valve: Sliding type valve facilitates easy operation & helps to control flow of soil.

Frame: The supporting frame consists of a square base, two columns, and placeholder for hopper. The placeholder is supported in two columns in the rear which enables freedom for moving hand, without compromising the support for loads.

Replaceable outlets: It facilitates using bags of various sizes.

Movable worktable helps in supporting bags of varying lengths while filling.

Poly-bag filler operation

Feed potting mixture to the hopper.

Position the bag on the table with the mouth facing the outlet of the poly-bag filler.

Opening the valve using the handle provided & allow the soil to fill the bag. The rate of flow can be controlled by operating the valve.

Prototype Test Results:

Testing of new prototype was conducted with bags of 3” x 10” size & capacity 0.03 Ft3 (1 kg)

It was observed that average time taken for filling a bag is approximately 17 seconds.