This should be done 1-2 weeks before the experiment begins -- the goal is to have a full pot of grass that is at least 1" tall. Ensure that each pot has a FULL amount of grass growing to the edges of the pot.
Methodology -- Label each pot as 1, 2, 3 and 4. Note in lab book that 1 = control (use distilled water if possible, if not, untreated tap water), 2 = .1% solution, 3= 1.0% solution, and 4=5% solution. Prepare at least a quart of each solution by using 1/10th gram of salt per 100ml of water for 2, 1 gram per 100 ml for 3, and 5 grams per 100 ml for 4.
Begin experiment by adding 10 ml (5 onto soil and 5 into reservoir) every fourth day. Ensure that all pots are placed in a warm and sunny area, but not directly in sun. Set up notebook to record the following results for each of the 4 pots (you will have 4 tables):
Day
Color
Height
Ave. Width of growth
Sediment?
Other observations. (ph of soil if possible)
1
Est. predetermined scale
Inches or mm
Inches or mm
Est. predetermined scale
5
9
13
17
21
25
29
Results -- if we were able to use distilled water, we...
Our variables are the concentration of NaCl in solution fed to plants. Out constants are type of soil, plant type, age of plant, treatment schedule, temperature, and light. The expectations are that as the concentration of salt increases, the plant growth will suffer (less green, less growth both horizontally and vertically, more alkaline in the ph test (if done), more sediment (undissolved salts), and less vigor.
Conclusions- if we were unable to use distilled water, we might have unknown variables that contributed to the experiment depending on water additives. This could be mitigated by leaving the water out for 24 hours initially to let any chlorine evaporate. We would likely expect the results to be graphed to show something similar to the following:
Figure 1 - Grass Experiment Height
REFERENCES
Cary, S. (2003). A Beginner's Guide to the Scientific Method. New York: Wadsworth.
Swift, C. And Koski, a.J. (2007). Growing Turf on Salt-Affected Sites. Colorado State
University Extension Office. Retrieved from: http://www.ext.colostate.edu/pubs/garden/07227.html
We would graph as many of the observations as possible, then do graphs of initial and…
