The Problem

Every summer the water problems in Dryville get worse. It is predicted that next summer water cannot be used for lawns or gardens for the entire month of July. Can laundry wastewater be used? How will this affect the growth of seeds?

Hypothesis

We are going to test and see how grass seeds grew if they were watered with dirty laundry water verses regular water. We also decided to see how the plants would react to being watered with biodegradable detergent.
 
 

Materials

3 10x10 potting trays

Grass seeds

Laundry detergent

Florescent lights with timers

3 beakers

 Potting soil

Water

Biodegradable detergent 

Ruler

 
 

Procedure

  1. Label the three trays Control, Detergent, Biodegradable.
  1. Split the potting soil into three equal amounts.
  2. Mix together water and regular laundry detergent in one beaker, water and biodegradable detergent in a second beaker and regular water in a third. Make sure that there is 650 ml of liquid in each beaker.
  3. Place an equal amount of moist soil in each of the three trays.
  4. Sprinkle grass seeds over the soil. (see setup)
  5. Place under florescent lights (8-hour timers).
  6. Water plants with 500ml every other day, and 750 ml for the weekends.
NOTE: if a puddle of water forms under the trays don't water them until the puddle disappears and if the puddle has an orange tint to it: drain.
 
 

Results

 We have watched the three trays for the last three and a half months. They all grew roughly at the same rate. The control, biodegradable and the detergent all had the same coloration. The detergent had a different growth pattern. To be exact grass grew along of the edges and then in the middle with a ring of no growth. (See picture)

On November 15, 1999 we decided to cut the grass because it was getting to long. The control grass and the biodegradable seemed to start to die. There was a lot of grass that had turned a brownish gray color that was matted to the ground. After the cut, the biodegradable began its downfall in which it never recovered. Within a few weeks the grass that had been growing in the biodegradable tray had almost completely disappeared, there was a very thin border of short grass that was left that has since then also died.

Surprisingly enough the detergent grass survived and lived the longest. In fact it is still growing to the day.

To see Growth Chart To see Daily Log
 
 

Conclusion

We discovered that watering grass with ordinary detergent does not have any extreme consequences to the grass' growth or coloration. When grass is watered with the detergent, the only difference from the control was that the grass was not as thick.

As to the biodegradable grass, there were no real differences from it and the control either. However the grass did fail to survive after being cut. We decided that one of the main reasons for this was that many people liked to pet the grass and in turn the grass was getting pushed down. So it became matted and started to decompose down there. If this experiment is recreated, we suggest that when letting the grass grow, cut it regularly, removing all of the cut grass and keep others from touching it. The last fact that we want to state is that biodegradable detergent doesn't necessary mean that the detergent is bio-safe. This could be another reason why the grass died.

So in conclusion, we feel that if you water the grass with dirty water, the grass will survive. But you must come to realize that we were only able to observe the short-term effects and have no idea the long term effects of watering grass with laundry detergent.
 
 

Links to

(Picture gallery)