Julia Barcelo
Environmental Studies 120
Final Internship Report
December 6, 2001

Internship: Organic Garden Weed Project

Goals and Objectives

The goal I worked out with Julia Gilden was to try and eradicate the clover that infested many beds in the organic garden. I had a lot of liberty and came up with my own plan and protocol. I decided to make this a bit of a scientific experiment. In short, I used four different methods of removing the clover and documenting which method was the most effective. In bed number one, I tilled the dirt and removed as many roots as possible, I predicted this would be quite effective and the clover would not grow back. In bed number two, I simply pulled out as much clover as I could without tools, and I predicted this would not be a successful method because the roots are not removed. Bed two is similar a control quadrant, because if my prediction was correct, it is fairly safe to assume the root is the most important part of the clover and if it is not harmed, the clover with grow back. In beds number three and four I used different strength ionic (salt) solutions to try and kill the clover without using dangerous pesticides. In bed number three I used a hypertonic salt solution. In bed number four, I originally used a weak, or hypotonic salt solution, but then decided to use just dry salt. In theory, the salt solutions should kill the clover. In doing this research, I will hopefully inform the garden of the most effective way to eradicate the clover without the use of harmful chemicals.

Scientific Principles

Plant cells take in water through a process called osmosis. The water passes through a selectively permeable membrane, which is an example of passive transport, meaning no energy is required to assist the water molecules across the membrane, into the cell. When a plant cell absorbs water, the cell wall will expand only so much before it exerts back a pressure that opposes further water uptake. When this occurs, a cell is turgid, or firm, which is a healthy state for plants. By using salt solutions, the water balance can be altered to change this turgid state. If a plant cell is surrounded by a hypertonic (hyper = too much) salt solution, it will lose water to its surroundings. This is not a healthy state for a plant cell because it will shrivel and pull the plasma membrane away from the cell wall causing plasmolysis, which usually kills the plant cells.

See attached Excel Spreadsheet of weekly progress

* I made an error when I said I would make a weak, or hypotonic solution because this is the ideal condition (described above) for a plant cell and would obviously not kill the clover. An isotonic solution would have caused the clover to wilt and probably die. However, without knowing the exact salt composition and what would be the ideal concentration for this particular clover, it was not possible to figure out what concentration would create an isotonic environment. That is why I decided to try a dry salt treatment, starting the third week of my experiment. *

Comments and observations on weekly progress

Week One: Much of the clover grows in and around bark. When I tilled bed one, I found that many of the roots had actually grown into the bark, which makes it quite difficult to remove them. The soil in this quadrant used to be a corn patch, so it is very healthy and “crawling” with worms. Also the soil contains fragments of newspaper, which I cannot explain, but was an interesting discovery and observation, along with a rubber band!

Week Two: I made a miscalculation with some units, so I reverted to a more remedial method to make my solution. I kept adding salt till I had a saturated solution, meaning the salt would no longer dissolve, and then used a little bit less than that amount. Interestingly enough, that amount was close to what I had calculated for my weak salt solution, 15 grams. I simply used one teaspoon of salt on bed three, which is obviously a weak solution. I am curious to see if the clover surrounding bed one will grow into the quadrant, demonstrating the behavior of clover.

Week Three: Quadrant three was destroyed, but easily rebuilt. The salt solution did start to work, and a lot of the clover turned brown or shrank. I reapplied the treatment this week. For the dry salt treatment in bed four, I did not decide on a specific amount. In my log I recorded using five tablespoons of salt, which was what it took to cover the quadrant, and I did this for a specific reason. If the organic garden people want use this method, it is easier and quicker to omit specific measurements, and just use enough for the targeted area. This method is indeed variable, because there is no exact amount, but practical for the context of my project. If the organic garden people employ this method, it will be much easier and quicker to omit specific measurements.

Week Four: A little more clover died in bed three, and it formed a green mush. The heavy rains the day before probably contributed to this result. This method seems to kill the clover above ground, but I do not think the roots are dying. This was a problem in bed two (which was hand pulled), and all the clover will grew back, so I am curious to see if the solution has an effect on the roots or not. My concern with the salt treatments is that they will probably have a similar affect on all plants and would not be a good method for killing clover in a bed full of desired plants. If the clover is isolated, then this method is easy and quick. I thought the rain would also aid bed four, but no change occurred. I reapplied both salt solutions.

Week Five: Not much more progress in bed three, but the bark and soil in the bed are not healthy looking. They are very dark and mushy, reinforcing my reservation for employing the technique around desired plants. Bed four was affected by the solution. The clover is very limp, and lying on the ground, but keeping a healthy green color. I reapplied the salt treatments.

Week Six: All progress in beds three and four has seemed to cease so I discontinued the salt treatments since the semester is almost over. I think the problem with the salt is that it does not kill all the roots, so the clover endures.

Week Seven: I was completely dumbfounded when I made my next weekly visit and discovered that the clover in beds three and four had almost all died. I was perplexed since I did not use a salt solution the previous week. Since I do not have time to continue taking data, I cannot know what produced this result. My scientific opinion is that, the salt finally got to the roots, and I'm sure there was plenty of excess salt in the surrounding soil to aid this result. That is just a hunch, but it is very strange that the clover died when I stopped using the treatments that harmed the clover previously. Bed four was more effective than bed three, another baffling observation. My best guess to that result is that the dry salt traveled through the soil to attack the roots, whereas the aqueous solution went into the leaves, and was not as strong by the time it traveled to the root.

Results and Conclusions

Bed one: I would consider this the most effective method for removing clover in an area that will be used for other plants in the future. The trick is to get all the roots out. The last week I discovered two or three little clover buds in this quadrant, which would most likely be suppressed if another specie were planted here.

Bed two: Not effective at all, all the clover grew back within a week. This was most likely because the “root” of the problem (ha-ha) was not taken care of.

Bed three: Eventually a fairly good method, but probably only for isolated clover. This aqueous solution still did not kill all the clover so I would not recommend this too highly.

Bed four: This turned out to be quite effective, there was no clover left in the bed week seven. This is a quick and easy method but has the same problem that bed three has. I would not recommend using this technique in a bed full of desired flora and fauna.

(To further prove that the salt solutions do work, all the clover outside of the beds was completely healthy. This proves that factors such as weather did not kill the clover, but that the salt solutions were effective.)

Time commitment

I met with both Amy Molitor and Julia Gilden and then started the hands on work. I did not have to drive to my internship, and the garden is fairly small so my work is accomplished quite efficiently. I had to discipline myself to go to the garden because I had no supervisor to plan specific meeting times with or get directions from. The quadrants I worked with were small areas, and once I had my methods perfected. It took less and less time.

9-11-01 - Tuesday (9:00-9:20) Meeting with Amy Molitor

9-14-01 - Friday (1:00-1:40) Meeting with Julia Gilden

10-01-01 - Monday (???) Bought project supplies

10-03-01 - Wednesday (3:00-6:00) Garden

10-12-01 - Friday (1:00-2:00) Calculations and planning

10-13-01 - Saturday (10:00 - 11:30) Garden

10-27-01 - Saturday (10:00 - 11:00) Garden

11-02-01 - Friday (1:00- 2:00) Garden

11-09-01 - Friday (12:30-1:30) Garden

11-16-01 - Friday (11:00 - 11:45) Garden

11-30-01 - Friday (2:00-2:10) Garden

12-01-01 - Saturday (ALL DAY) did research and made poster

12-02-01 - Sunday (???) Took quadrants down and collected samples

 

Problems and Suggestions

I was very frustrated at first because I had no structure to follow and it sounded like I was just going to be pulling weeds out of the ground. I felt that my internship was insignificant compared to people working with large agencies, but I was wrong, my internship is much different, but not less important. I had trouble coming up with reasons why this benefited any part of the community or me, so I decided to take a different approach, and am now pleased with the results. There was a suggestion on my mid-semester report saying that I could educate the local community on gardening techniques. This would be a good pursuit, but my research was too inconclusive until now to teach anything useful.

This was the original definition of what my internship would be: “Identify and record all of the so-called `weeds' that are in the garden. Intern would need to do thorough research to learn about the different plants and how they have been used. Create a permanent educational sign on weeds for the garden”. This was not even close to what Julia Gilden wanted me to do. I did not really have a problem with being flexible, but I think the guidelines should be followed more closely, or specify that the internship will be designing one's own protocol after working out a plant with the organic garden people. I had to sit down and think of my own objectives and the independence made it quite fun.

There were a few other problems, caused by human error. I had been taking photographs of the four quadrants all semester. I captured the first day, and any day that showed change thereafter. This was going to be the focus of my poster presentation, until I made the unpleasant discovery that the film had not loaded correctly and I had no pictures.

There was a problem I encountered with my research at the end of the semester. I had discontinued the salt treatments, and the next week I came back to see that beds three and four were virtually clover free. I was baffled by this result, it seemed as if stopping the treatments had killed the clover. I doubt this is what happened, and I think there was a lot of salt remaining in the soil, it just took more time to work. If I had a couple more weeks, I would do further experimentation to figure out why I found this result.

I do not know if anyone will do an internship like this in the future, but there is one problem I foresee, mainly for the fall semester. I was lucky and it did not snow while conduction my experiments. If the ground had frozen I would not have been able to continue my experimentation. The reason I mention this is to warn future people to get the fieldwork done early, before the snow and freezing weather arrives.

Experience and Success

After getting over my initial frustration, I have been very enthusiastic about my work in the garden. It feels good to have no structure, because I have to rely on myself to do everything. This has been such a great learning experience because I am using scientific methods and doing actual studies in the field just as many scientists would. Looking back at my methods, I think I should have applied the salt treatments more than once a week. I wanted my results to be applicable to the organic garden, and I know most of the people go over on the weekends, and do not have time for much else. I included that factor in my methods so others could then realistically apply them.

As we talked about in class one day, there are different kinds of “environmentalists”. Some people fight for the environment by attending protests, which is necessary and beneficial. Personally, I like to actually go out and be active, involving myself in hands-on projects like this one. Without scientific research, we would not know how huge our environmental problems are. Scientific research may develop ways to redeem some of the damage we have inflicted on the environment and prevent more harm from coming. These were some of the reflections I had while working on my internship. I know the clover in the organic garden is not damaging the ozone layer, but it is the process that I am learning to go through that holds the significance.