Chapter 4: Greywater experiments on two types of turf – Experimental Methods… …
4.6 Tools for cutting and collection of turf samples …
4.6.1 Frame for standardising the cutting
An aluminium frame was constructed from a 3 mm x 40 mm flat bar for use as a guide to cutting equal areas of turf from within the pots. The frame was 40 mm high and covered an area of approximately 180 mm x 180 mm and so ensured that turf samples could be cut away from the edges of the 250 mm x 250 mm pots. All around the outside of the frame a piece of woven plastic cloth was attached so that grass outside the frame would be covered, and not accidentally cut and sucked up by the vacuum collection system used. The grass was cut so that it was level with the top of the frame, using flat blade scissors. Turf cut heights with the use of the frame tended to average about 45 mm for Tall Fescue and 50 mm for Kikuyu. A photograph of the frame used is shown in Figure 4.2 below (Note: this shows the frame sitting on the ground between the pots. The grass is not a cut sample).
Figure 4.2 – Frame that was used as a guide for cutting turf
The frame was not of a perfect square shape but was calculated to enclose an area of 331cm2 by carefully tracing the frame shape on several pieces of 80 gsm paper, and then comparing the weights of the paper cut outs against the weights of full sheets.
The area was also confirmed by taking several measurements to estimate the average dimensions of the frame. To calculate the growth rates per m2 a factor of 30.2 was therefore determined from the 331cm2 area enclosed by the frame.
4.6.2 Vacuum collection system for cut turf
A suction system was used to collect the grass as it was being clipped. The system was constructed by attaching the outlet of an external “Turbo Dust Filter” to the suction hose of a vacuum cleaner and then connecting a flexible piece of swimming pool filter hose to the inlet of the Turbo Dust Filter. The grass clippings did not reach the vacuum cleaner but were caught in the collection chamber of the Turbo Dust Filter, from which they were easily tipped into a paper bag. About five clippings always got caught in the hose where it was attached to the inlet of Turbo Dust Filter.
This was not a problem because the hose was easily removable for collecting the clippings. The unbranded Turbo Dust Filter was purchased from a local Godfreys vacuum cleaner store. The vacuum collection system is shown in Figure 4.3 below.
Figure 4.3 – Vacuum collection system for cut turf
The presence of dew often delayed the cutting of the grass until mid to late morning because pieces of wet grass tended to stick inside the hose and to the walls of the
collection chamber. In the early stages of the experiments, to avoid further wetting of the grass, the watering was suspended until after the cutting, but this method almost resulted in the loss of a few pots of grass on a hot day. The procedure of watering first thing in the morning on grass cutting days was therefore adopted, and by the time all watering was completed the first watered pots were usually dry enough for cutting.
4.6.3 Extra tools used
The following extra tools were needed to cut and collect the turf:
1. Small brush attachment from the vacuum cleaner – The turf samples were gently vacuumed before cutting to remove contaminants that could affect the weight of collected turf, and to free up some tangled blades of grass. Common contaminates included loose sand particles, small leaves, occasional insect, and some dry turf clippings that may have resulted from the previous trimming of the turf sections along the edges of the pots. The brush attachment was used because it provided a gentler contact surface than the end of the hose, and so minimised damage to the uncut grass undergoing suction.
2. Solid house brick – The brick was placed on the frame as a means of keeping the frame in place and applying some pressure. The brick also served as a rest for the hand holding the vacuum hose just above the grass, and also provided a cutting guide away from the edges of the frame. After cutting the exposed grass within the frame, the brick was repositioned to expose other sections.
Initially U-shaped wire clips were used to keep the frame from moving however the brick method was considered to be superior.
3. Flat blade scissors – These commonly available scissors cut close to the frame and were cheap enough to be frequently replaced when needed.
4. Plastic watering spike – This was a round and tapered spike normally
intended as an attachment to a plastic bottle for sub surface watering of plants.
It was very useful to reposition some turf that obviously may have been pushed to the wrong side of the frame when placing it down.