Dirty Beans: Analysis of Soil Quality and Bean Growth

 

Abstract

Check out our Quicktime bean movie!

Check out some of the pictures that we took

Check out our Power Point of our project

 

Dirty Beans: Analysis of Soil Quality and Bean Growth
Bryan Glosik and Nick Delphia

INTRODUCTION

The main focus and purpose of this experiment was to observe a large number of bean plants growing in a variety of soils. (metro-mix, topsoil, sandy soil, and clay) There was fertilizer added to half of each soil sample. We looked at which soils yielded the most productive and successful bean plants and looked at whether or not the fertilizer had a significant effect on the growth or yield of the bean plants.

Hypothesis:

Our hypotheses were that the beans would grow best in the topsoil samples and plants would fare better in soil that was fertilized as compared to plants in the same soil type without fertilizer. We thought that the topsoil would yield the best plant growth due to the rich nutrient value found in natural topsoil. Other researchers have found that the numbers of beneficial microorganisms that contribute to plant growth "were higher in soils amended with composted plant materials in experiment station plots" (L. R Bulluck III et al 157).

Predictions:

We believed that the beans would have a difficult time growing in the clay due to the lack of air circulation getting to the roots to stimulate growth (Bouma and Bryla 215). We also thought it would be hard for water to get to the seeds because of the density and poor water retention properties of the clay. We predicted that the water would sit on top of the clay or just flow around it and drain out the bottom of the flat and that therefore the been plants in the clay sould not get sufficient water. We suspected that the clay might dry out like a brick and become too hard for the beans to grow in. With this experiment, we hoped that we would find out which one of our soils would be best for the growth of beans.

Our Interest

We find this subject to be interesting due to personal past experiences. Nick grew up in Columbus, a city impossible to drive out of without being exposed to large amounts of agricultural land. Nick's father has also farmed a plot of land in a city owned garden for as long as Nick remembers. Nick has always been fascinated by growing plants sincewatching and helping his dad farm as a child. They may be a bit easier to take care of then beans, but Nick also has several cacti at home. He has had one of them for almost eleven years, and the other one for about nine years.

Bryan is from northern Ohio, which probably has an even larger amount of farmland than the areas surrounding Columbus. Bryan did an internship where he assisted in a USDA survey and counted tillage in bean fields. he was helping with research about soil quality and how it related to tilling the soil. Bryan and the people he was woking with went from field to field counting tillage. Basically, Bryan was helping to survey how much the different farmers had overturned the earth in their fields.

RELEVANCE

Our research project ties into a large-scale issue that effects the entire world. Human beings could not exist as they do today without farming. Legumes are an important crop across the earth. Chances are, that on any given day you could very likely end up eating legumes. Legumes are the basic food staple for much of the world. Beans are "grown extensively in all major continental areas" (Graham & Ranalli 131). Many people depend on beans for survival. "Common bean (Phaseolus vulgaris) is the most important food legume on earth, providing scarce nutrients to many people in developing countries" (Fisher et al 63). We won't be able to feed the world with the results of this experiment, but we might be able to reach a better understanding of how farmers the world over have to cope with different qualities of soil.

Because legumes are such an important food source for so much of the world, it is important to consider what may be affecting farmer's ability to produce legumes. The web site Fertilizing Dry Beans says "Legumes, such as dry beans, fix a portion of their total nitrogen from the atmosphere thus nitrogen fertilizers usually are not needed" The same web-site says that"Phosphorus often is the most limiting nutrient for dry beans". Fisher, Eissenstat and Lynch found that in a "sand culture", "the lowest phosphorus treatment induced severe deficiency, at the lower limit of what might be called agricultural production" (Fisher et al 69). We may be able to support this hypothesis as one of the soils that we will be testing is sandy soil. Farmers need to use a fertilizer that is rich in phosphorus if they want their bean crops to be able to flourish. We are using a fertilizer that has phosphorus in it

Water can also play an obvious part in determining how well bean plants fare in a given environment. Sangakkara, Frehner, and Noseberger write that "legumes are grown in a wide range of environments, and water stress is considered the principal environmental factor limiting growth and yield" (Sangakkara et al 73). Other researchers also found that "lack of moisture and low soil fertility" limit "bean production" (Boutra & Sanders 229). Water is one of the key parts of our experiment in that we will be carfully making sure to water all plants the same

Erosion is an important problem that farmers must face. As the good top-soil erodes away, farmers may be forced to use lower quality soils (like sand or clay). There has been much research on soil erosion and its effect on agriculture, but not enough. R. Evans writes "There is a need for continuing (as well as new) projects to monitor erosion in the field" (Evans 205). Erosion affects farmers everywhere. Farmers as far away as Kenya and Tanzania have to struggle against erosion Erosion

Governments all over the world are concerned with agriculture. There is a huge financial commitment by governments to help their farmers. Farmers often choose land on a flood plain for their crops because it is more fertile. Of course, the trouble with flood plains is that they flood from time to time. This obviously does not go well with the farmers. "A logical result of farming in the floodplains was that owners who had struggled to clear these highly productive lands wanted to protect them from flood waters" Levees The farmers have a rather large influence on the governments, since it is they who provide the food, so the governments do all they can to prevent floods.

Since soil erosion is such a problem, farmers must come up with ways to limit its negative effects. To limit the amount of soil lost to erosion, many farmers use a process called no-till farming. As the name implies, the land is not tilled. Instead of turning over and fertilizing the land, the farmers simply alternate crops so as to be less stressing on the soil. To add nitrogen to the soil, the crops that are planted are switched with beans every now and then so that the beans can add nitrogen to the soil through a process called nitrogen fixation. "N contribution by root nodules is often viewed as the major role of symbiotic legumes in cropping systems" (Dakora 39-40). It is possible that nitrogen fixation could contribute to the growth of our own bean plants in this experiment

Legumes are a very interesting crop because of their nitrogen fixing capabilities, which are dependant in part on the nutrient content of the soil (Leidi & Rodriguez-Navarro 337). This is a process that requires oxygen in the soil around the roots. The soils that we are using have a varying degree of porosity. Some researchers have stated that there is "little understanding how soil texture and water content may affect these estimates [of root and soil respiration]"(Bouma & Bryla 215). Other researchers have found that "aeration characteristics were strongly influenced by the texture and bulk density" of the soils they used (Rasiah and Kay 92)

The web site Fertilizing Dry Beans says "Legumes, such as dry beans, fix a portion of their total nitrogen from the atmosphere thus nitrogen fertilizers usually are not needed" The same web-site says that"Phosphorus often is the most limiting nutrient for dry beans"

METHODS/EXPERIMENTAL DESIGN

Our experimental design and method were. originally a very simple and clear plan. We used four soil types in this experiment. Half of the bean plants in each soil type were fertilized while the other half were unfertilized.

We grew our plants in the Boyd greenhouse. The greenhouse had a fertilized waterline that we used on our fertilized plants. The greenhouse was heated, so the plants were in a stable environment that was supportive of plant growth.

The pre-made mixture of fertilizer in the fertilized water line that we used contained a 20:10:20 ratio (nitrogen: phosphorus: potash). The water in the fertilizer solution was tap water that had been softened with a phosphate-based water softener (plants wouldn't respond well to the traditional salt-based softeners). To eliminate the possibility that our results be skewed from differences in the plain water, and the water in the fertilizer solution, we used the same phosphate-softened water that was used in the fertilizer solution as our plain water for our unfertilized plant.

For our control soil, we used metro-mix 350. Metro-mix 350 is designed specifically for growing plants. Our other test soils were natural topsoil from Western Woods, clay from Pfeiffer Park, and sandy soil from Pfeiffer Park. Similar studies have been done by other researchers (Reidell, Beck et al 316). We had one flat for each type of soil. There were 24 plants planted per flat, half of which were watered with the fertilized mixture while the other half were watered with plain water.

Each row of the plants was labeled with a letter in the alphabet. Each plant was labeled individually by the row letter and however many over from the left it was. (ie. B1, B2, B3, B4) Plant numbers 1-3 in each of the rows were the non-fertilized plants and plants were marked with an additional F for fertilized.

When we were collecting data, there were certain things we looked for. We wrote down, for each plant, the plant number, soil type, fertilized or unfertilized, height, number of leaves, number of stems off of the stalk, and the number of buds. Also, every Monday, we took a photograph of the plants with a digital camera. For six weeks we took this data. At the end of the six weeks we will had the class measure the biomass of each of our bean plants. This method of measuring the dry weight of plants is not new. Dracup and Kirby developed an experiment in which they measured the dry weight of lupins in Australia (Dracup, Kirby, p. 211).

Once we had all of our data, we compared the growth and yield of plants from one soil with those of the same soil that were fertilized. This assessed the effect of fertilizer on plant growth. For our analyses, we made graphs with two lines that compare growth with and without fertilizers and another set of graphs that compares the numbers of stems, leaves, and buds on plants with fertilizers to those from plants without fertilizers.

We compared these same characteristics between plants in different soils to assess how the soils affected plant growth. We compared the growth and yield of plants in the unfertilized soils to each other and made the same comparisons between the plants in the fertilized soils. The comparisons were made among each type of fertilized soil, and again among each type of unfertilized soil. We used a t-test to analyze the statistical validity of any differences found between fertilized and unfertilized. For comparisons between the different soils we used the analysis of variance found in the JUMP statistics program.

CHECK OUT THE DATA SHEETS FOR BOTH EXPERIMENTS A & B

THIS WAS OUR ORIGINAL RESEARCH TIMELINE:

A Second Experiment

We were three weeks into our first experimental setup, and things weren't quite going as well as we would have liked. It appeared that our soil choices were a little too extreme. The clay was not growing anything. We essentialy had a flat of little grey bricks. The sandy soil and top soil were also not yielding many bean plants. The most successful flat was the unfertilized metro mix. We decided to continue running this experiment but add a second experimental setup so that we could hopefully have enough data from the second experiment or between the two experiments to run some statistical analyses.

For our second setup we used three flats. Each flat had a different type of soil in it. The soils were an organic topsoil, composted cow manure and humus, and the metro mix. We planted each cup with two beans, so that hopefully, we would have a better germination rate. We labled each row of the flats in experiment B, but not each cup. We designated a number for each cup by observing how far away it was from the front of its flat. The workers of the greenhouse watered the new flats for us, while we continued to water and observe the original flats. The new flats were only be watered with tap water. We decided this because the flats with the most plants in experiment A were those that were not fertilized. The measurments that we did on experiment B were the same as experiment A. Therefore we used essentially the same data sheet for experiment B as the one for experiment A. The only real differences were that there were different soil types, and that experiment B had no fertilized soils.

Predictions For Second Experiment

We predicted that the plants in the composted manure would grow the best since manure is a natural fertilizer.

this was our setup for both of our experiments

this was the setup for our first experiment

this was our setup for the second experiment

Class Assignment

We took the bags to class, and had some students volounteer to calculate their masses. These students recorded the masses in a database on a computer for us, while the rest of the students watched a presentation about Jump, the statistics program that we used to anylize our data.

Results/Discussion

Experiment A

We found there to be significantly less leaves on the unfertilized plants when compared to our fertilized plants. This figure shows how the bulk of the data doesn't even overlap.Our p-value was less than .05, so, from looking at this figure, we rejected the null hypothesis that there would be no significant difference in the number of leaves on fertilized plants versus unfertilized plants. This figure supports the alternative hypothesis that there would be more leaves produced by fertilized plants than unfertilized plants. Not all of our data was this supportive of our alternative hypothesis, however.

The numbers of buds produced by fertilized and unfertilized plants were not significantly different. The figure shows, pretty clearly, how there is a large amount in overlap between the the two groups of plants. The t-Test shows the p-value to be greater than 0.05. Our p-value was 0.3463 so we failed to reject the null hypothesis. There was no significant difference in the bud counts of both the fertilized and unfertilized plants. This does not support our alternative hypothesis that the fertilized plants would yield more buds than the unfertilized plants.

 

This figure clearly shows how the plants grown in sand produced fewer buds than the plants in the other two soils. Our analysis of variance shows the probability of observations from all three soil types being similar to be 0.0303. As this is less than 0.05, we reject our null hypothesis that there would be no differance, and fail to reject our alternative hypothesis that there is a significant difference. After looking at the figure, it is clear that the sandy soil is the odd-man out in this comparison. One can see from the circles on the right that the bud-count data from the sandy soil hardly overlaps the other two soils at all. This supports our hypothesis that the plants would fair better in topsoil.

Although the analysis of variance shows us that there is no significant difference between the bio-masses of the three soil types, one can see, simply by looking at the graph, that the topsoil had plants with greater bio-masses than the other two soil types. Since our analysis of variance doesn't support the alternitive hypothesis, we must reject the alternative hypothesis that the topsoil would yield larger plants. Inspite of this, we can still say that, from just looking at the graph, we feel pretty good about our hypothesis.

 

We thought that, in general, that the fertilized plants would have a greater biomass than the unfertilized plants. One can see from this figure that the fertilized plants have a greater range of heights than the unfertilized plants. However, from out T-test we can say that there is no significant difference (p > .05).

 

After studying the graphs one can conclude that for the most part the fertilized (pink line) has a much higher growth rate than the unfertilized (blue line). Looking at the plant height in the sand there is a much more consistant growth of the bean plants in the fertilized plot. There is a slight increse in the unfertilized sand for about a week, but later returns to it's previous growth rate. The average plant height in the topsoil the fertilized has a much steadier slope although the unfertilized were higher at the begining. They continued thier growth and ended up higher than the unfertilized. In the metro-mix soil, the fertilized also had the highest in growth. The pink line started and ended at a higher height than the blue line.

 

The results of the average leaf count were very similar to the average height. For all of the graphs, it can be seen that the fertilized had by far the most leaves in all of the soils. During the first weeks of the experiment the leaf counts of both the pink and the blue line started out very close to each other. However, like the average height graphs, the fertilized ended up with a higher number in growth. In this case there were much more leaves in the fertilized than the unfertilized at the end of the experiment.

 

Experiment B- just as fun and just as inconclusive

We thought that the composted cow manure would yield bigger and more fruitful plants than the other two soild in experiment B. One may notice, when examining our figures, that the words "composted cow manure" don't appear anywhere on any of the figures for experiment B. This is, quite simply, because nothing grew in the cow manure. One can see from the above figure that there was no significant difference between the heights of plants in Metro-Mix and Organic Topsoil.There was, however a significant difference between the numbers of buds produced by plants in the Metro-Mix as compared to the Organic Topsoil as can be seen in the figure below on the left. With a p-value of 0.002 our data supports that there is a significant difference between the number of buds produced in the two soils. We also found there to be a significant difference in the numbers of leaves produced by the two soil types. One can see from the figure on the right below that the the leafcount is even more significantly different between the two soils than the bud count was. The p-value for leaf count was 0.0001. The Metro-Mix yielded plants with significantly more leaves than the Organic Topsoil.

Although the Metro-Mix yielded plants with significantly more buds than the plants in the Organic Topsoil, the two soils yielded plants with relativly similar bio-masses. The figure below shows how the data is very similar. The p-value is 0.9897. This essentially means that the probability of getting the plants with equal bio-masses is 98.97%. This definitely supports the null hypothesis that there sould be no significant difference in the Bio-masses of plants from the two soils.

Our t-test showed that there was no significant difference between the plant heights from Metro-Mix and Organic Topsoil. It was no surpise that when we plotted the average plant heights over time for the two soils, and found the lines to be very similar in slope, as can be seen on the left graph below. The graph on the right shows the average number of leaves that we counted on the plants each week for both types of soil. Since our t-test showed there to be significantly more leaves yielded by the Metro-Mix than the Organic Topsoil, we were not surprised by how this graph turned out either. One can see that the Metro-Mix plants consistantly had more leaves than the plants in the Organic Topsoil throughout the entire course of our research.

 

Over-All Conclusions

From our data, we can conclude that topsoil or metro-mix are better choices for planting beans than sand. Since a farmer cannot actually fill his field with potting soil, we feel that topsoil is the best choice for bean-planting in a real-life situation. We found fertilizer to increase the number of leaves produced by our plants, but, from our data, we can't support our hypothesis that there would be more buds on fertilized plants, as we found no significant difference in the bud-count of fertilized versus unfertilized plants. We think that further study should be done to test this trend. Future researchers could test to see if fertilizer increases the number of beans produced, the size of the beans produced, or the rate of growth of the plants, all of which were not considered in this study.

In our second experiment, we found that both the bud-count and leaf-count increased when plants were grown in the metro-mix instead of the organic topsoil. This may suggest that soil type has a greater effect than fertilization on the yield of bean plants. We were incorect in our prediction that plants in the composted cow manure would grow better. The reasons why our seeds would not grow in the manure could be yet another point for further research.

In both of our experiments, the specific biotic and abiotic factors that may benefit plant growth were not thouroughly researched for each of our soil types. Future studies should pay carful attention to such things as nutrient content, microbial content, and pH of the soil.

Sources of Error:

A possible source of error in the first experiment could be that, although we offered the same amount of water to each flat on any given day, we did not have any set schedule as to what days we would water. The plants, therefor, did not recieve a regular watering schedule. We also did not take into account the different water holding capacities of our soils. The clay, being so dense, obviously would have needed to be watered much more frequently than the other soils just to mantain the same level of moisture. When we were measuring the height of the plants, we didn't measure how tall each plant could be stretched out, but how tall it was actually standing at that time. As a result, if a plant was leaning or had a bent stalk from water on it's leaves, or if it had dried out some over the past week, it was possible for a plant to be shorter one week than it was the week before. There was no set plan for how to measure, so there were differences in measurment practices between the two data collectors. When we measured the bio-mass of the plants, some of them were so dry and brittle, that they broke when we were trying to move tem from the oven into their bags. We had 0.09 g of uncounted plant matter left over at the end of the procedure. If we were to do this experiment again, we would take extra steps to make sure that enough seeds actually germinated. We would also choose more realistic soil types (no more clay).

 

BIBLIOGRAPHY

Bouma, Tjeerd J. & David R. Bryla. 2000. "On the assessment of root and soil respiration for soils of different textures: interactions with soil moisture contents and soil CO2 concentrations". Plant and Soil 227: 215-221.

This article discusses the necessity for soil respiration in order for the plant to survive. One of our soil types is clay from the creek. We think that this will not allow the been roots to get enough oxygen

Boutraa, T. & F. E. Sanders. 2001. "Effects of Interactions of Moisture Regime and Nutrient Addition on Nodulation and Carbon Partitioning in Two Cultivars of Bean (Phaseolus vulgaris L.)" J. Agronomy & Crop Science. vol. 186: 229-337.

This article describes the major limiting factors on bean growth, which is what we are concerned with as well.

Bulluck III, L. R., M. Brosius, G. K. Evanylo & J. B. Ristaino. 2002. "Organic and synthetic fertility amenments influence soil microbial, physical and chemical properties on organic and conventional farms." Applied Soil Ecology. vol. 19: 147-160.

This article describes an experiment in which the bean plants grew better in soils that had natural decomposed materials in them than they did in regular unfertilized soils. This helped us in our prediction.

Dacrup, Miles & E. J. M. Kirby. "Pod and seed growth and development of narrow-leafed lupin in a water limited mediterranean-type environment". Field Crops Research, vol. 48: 209-222.

This article discusses factors that contribute to legume development. We chose to use it because we are concerned with the development of our own legume plants.

Dakora, Felix D. 2002."Defining new roles for plant and rhizobial molecules in sole and mixed plant cultures involving symbiotic legumes". New Phytologist. vol 158: 39-49.

This article discusses properties of soil that can lead to increased grain yields of legume plants. We selected this article because it is relevant to what we are doing.

Evans, R. 2002. "An alternative way to assess water erosion of cultivated land † field-based measurements: and analysis of some results." Applied Geography. Vol. 22: 187-208.

We chose this artical because it discusses the importance of dealing with erosion, which we address in our relevance section.

Fisher, C. T., David M. Eissenstat & Jonathan P. Lynch. 2002. "Lack of evidence for programmed root senescence in common bean (Phaseolus vulgaris) growth at different levels of phosphorus supply."New Phytologist. vol. 153: 63-71.

This article discusses the importance of beans as a staple food crop for the world, and describes how the growth of beans was affected when the nutrient levels in the soil were changed.

Graham, P. H. & P. Ranalli. 1997. "Common bean (Phaseolus vulgaris L.)" Field Crops Research. vol. 53: 131-146.

This article discusses the basic factors that go into bean production, including the key limiting factors of soil.

Leidi, E. O. & D. N. Rodriguez-Navarro. 2000. "Nitrogen and phosphorus availability limit N2 fixation in bean." New Phytologist. vol. 147: 337-346.

This article discusses the affect of nutrient availabilty on the nitrogen fixation capabilities of bean plants. This ties into the larger issue that our project relates to.

Rasiah, V. & B. D. Kay. 1998. "Legume N mineralization: effect of aeration and size distribution of water-filled pores." Soil Biology & Biochemistry. vol 30: 89-96.

This article discusses the importance of the pores in the soil, and their effect on the growth of legumes.

Ridell, Walter E., Dwayne L. Beck, and Thomas E. Schumacher. 2000. "Corn Response to Fertilizer placement Treatments in an Irrigated No-Till System". Agronomy Journal, vol. 92: 316-320.

We chose this article because it addresses the use of fertilizers on legumes. This is what we are doing in our experiment, so it made sense that weêd want this article for a reference.

Sangakkara, U. R., M. Frehner, & J. Nosberger. "Influence of Soil Moisture and Fertilizer Potassium on the Vegetative Growth of Mungbean (Vigna radiata L. Wilczek) and Cowpea (Vigna unguiculata L.Walp)”. Journal of Agronomy and Crop Science, vol. 186: 73-81.

This article discusses the effect of water and fertilizer on bean plants. Since this is exactly what we are doing with our experiment, we chose to use this article.