The+Different+Impacts+on+Soil

How does human influence impact the growth of plants in certain areas of Flat Rock Brook?


**Abstract:**
Humans influence the environment they live in constantly, and Flat Rock Brook is no different. Knowing this, we took soil from three different areas in Flat Rock Brook, each with differing distances from human civilization. Along with potting soil as a comparison, we planted vegetable seeds into plots of soil from each area, to see which grew the best, and which grew the worst. Ultimately, we came upon the discovery that the soil closest to human civilization produced the best plants, with the moderately distanced soil producing strong, but not as strong as soil 1, plants, the very isolated soil producing weak plants, and the potting soil producing the weakest.

**Hypothesis:**
We hypothesized that plants which grow on soil near human influence will grow less successfully than those which grow in areas untouched by humans. We assumed this, as it seems likely that human influence will impede the plant growth process.

**Goal:**
We wanted to compare the fertility and other growth factors of three samples of soil. Each sample will be taken from areas which have different amounts of human impact. By doing such we can visually find correlation between human impact and soil/ plant growth.

**Materials:**

 * Soil samples from 3 different areas in Flat Rock Brook.
 * Potting soil.
 * 4 plastic soil pots, with 9 (in rows of 3) sections for individual seeds.
 * Distilled water to water the plants.
 * Plant seeds.
 * GPS device - Magellan 400 GPS

**Methods:**
<span style="COLOR: rgb(0,17,255)">At Flat Rock Brook, we dug up three samples of soil from different areas, put them in plastic bags, and labeled the bags 1, 2, and 3. Soil 1 was from an area closest to a human habitat (near the entrance of Flat Rock Brook), soil 2 was taken from further inland (near the brook), and soil 3 was from an area furthest away from human contact. We obtained four congruent containers, each with nine plant holes, and filled each respectively with soil 1, 2, 3, and 4 (the commercial soil). Soil 4 is the standard soil that is untouched by the natural chemicals and debris found in typical soil, and we can assume that its plants will grow well. Then, we planted the seeds and watered them with distilled water. Distilled water is purified, so it is free of harmful chemicals that could affect the plants. By comparing and contrasting the physical changes in the growths of the plants in four different pots, we deduced from the visual evidence the success of growth that each type of soil provides. <span style="FONT-FAMILY: Arial,Helvetica,sans-serif"> <span style="COLOR: rgb(233,43,43)">

<span style="COLOR: rgb(233,43,43)">**Background Information:**
<span style="COLOR: rgb(0,17,255)">Soil formation is generated by biotic and abiotic factors such as temperature, wind, types of organisms, and topography. Although these factors are influential at different degrees in different regions, soils in general retain their basic morphology, and by the differentiation of horizon, the soils are layered according to the time each type was formed. The morphology of every soil is the expression of fundamental processes interacting with one another over multiple spatial scales (from micrometers to kilometers) and temporal scales (from days to millennia). Horizons at the surface (A horizons) are often enriched with organic matter, while deeper horizons (B horizons) may have accumulations of clay, calcium carbonate, metal-organic complexes, or other materials. Formation of A horizons is relatively rapid because organic matter accumulates in a few centuries to a millennium. Formation of B horizons commonly takes many thousands of years to become fully expressed. In this sense, soils can range from young to middle-age to old. As soil formation progresses, soils generally tend to become increasingly anisotropic as they differentiate into greater kinds and numbers.

Soil has to retain an appropriate pH value so that they can have as many minerals as they can. When the pH value is below 7, the soil becomes acidic and contains iron, magnese, boron, cooper, or zinc; when vice versa, it is alkaline and can have phosphurus, potassium, sulphur, or molybedenyum. It is important for soil to retain the neutral value of pH, for it can attain such essential nutrients as nitrogen, calcium, or magnesium.But human impact disturbs the soils to do this job, just like air pollution and the deposition of acid precipitation greatly influence the increasing of the level of rain acidity. If the pH value approaches zero or above 13, the soil will have a low buffering capacity because of its low calcium content. The high level of acidity in soil will cause an exchange between hydrogen (H+) ions and some cations like potassium (K+), magnesium (Mg2+), and calcium (Ca2+). These cations will be eradicated from the soil, while the sulfate ions will be put in.

<span style="COLOR: rgb(0,17,255)">Soils are subject to major geological and meteorological changes, and every time a disaster occurs, the composition of soils always changes. Just like these natural disturbances, human impact highly affects soil. Buildings, cars, factories, and other environmental-influencing factors which interact with abiotic factors can have a huge impact on environment. Soil, meanwhile, may receive either favorable or unfavorable effects from changed environments. Its resistance and resilience to change may prevent itself from being harmed, and the strength of its resistance and resilience can be determined by the soil composition. Soil with rich organic matters can have resistance against environmental changes without any dilemmas, and thus can go back to its original state.

To be added to the organic matters in soil, soil formation is done by two types of elements, organic and inorganic. Inorganic soils are the rocks that have been fragmented into small pieces, and the best examples of this kind are pebbles, gravel, or any small particles like sand. Meanwhile, organic soil is from the dead living materials that have been degenerated and transformed into soil.

The inorganic soils are divided into sand, silt, and clay. Sand is the largest particle, silt the middle, and clay the smallest. Sand and silt are outstanding for retaining moisture on soil and plants and thus essential for the primary growth of root. Clay, on the other hand, prevents the penetration of water into plants, which would after all have a problem with growing when encountering this soil type. It provides the chemical backbone for the entire soil system. The so-called parent rocks are the basis for soil composition, balancing, for example, the pH with calcium extracted from the sediment of the limestone. The rocks also decide the likelihood of a certain grain's growth because of their size that might not provide the gaps big enough to allow the maturity of the plants.

Furthermore, different climates determine different soil compositions. The strength of wind may break down the big parent rocks into pieces and spread them out to different regions. So soil composition sometimes depends on the types of parent rocks around in the area where the soil is in. Another example is the acidity of rain, which cause soil to lose its major components and break chemical bonds within these elements.

More important, however, is organic material that has been attained from biotic factors in an ecosystem. Because the matters are organic, they contain carbon fundamentally and can feed on organisms. Its release to the atmosphere may bring about global and environmental issues such as global warning or greenhouse effect. Along with carbon, the major nutrients are calcium, magnesium, sulphur, iron, zinc, copper, cobalt, boron, and others. Most should be provided by any sort of feasible method, since soil doesn’t inherently have them. They can be obtained from water, which contains not only oxygen and carbon ions but also other things mentioned above; water can be made up with different chemical elements and thus differ in quality from region to region.

Now that human activity has escalated, environment has changed accordingly, causing serious concerns to living conditions of people. Notable is salinization on various areas, brought by irrigation, dryland, urbanization, coastal zones, and lastly, interbasin water transfers. Irrigation salinity influences the most land, which is ranged from 10 to 50% of the entire lands in the U.S.. As river waters show an immoderate amount of dissolved salts, irrigation is suspected to be one of the major impacts on soil. More evident is the fact that irrigation water leads to a rise in the water table enough to bring about capillary rise and subsequent evaporative concentration to take place. Checking the groundwater level, researchers can find out the work of capillary forces to bring moisture to the surface were evaporation occurs. Thus, irrigation lead to rapid rises in the position of the water table. Salt contains calcium and magnesium components, which will combine into carbonates and, with regards to the environment, leave sodium ions dominant in the soil solution. Then, the ions are absorbed by colloidal clay particles, making soil impermeable to water and unfavorable to root development. The outcome from this phenomenon is the dearth of vegetation and plants above the ground.

Other human impact is the use of chemical fertilizer. Since nitrate started to be imported from Chile in the early nineteenth century, its consumption rate soared very steeply, bringing the amount of consumption up to 80 million tones nowadays, a dramatic increase in comparison with 50000 tones in the 1940's. As people favored this natural resource, they started to integrate it with superphosphates, making a synthetic fertilizer. Its effect was to increase agricultural productivity and yield a considerable amount of crops. However, synthetic fertilizer was found to contaminate water, as it can accelerate soil-structure deterioration and soil erosion. Then the water will repel some soils, and the result will be the reduction of soil infiltration rates and the augment of erosion rates by overland flows. Furthermore, soil acidity can be originated from this harmful process and generate a series of lack of major nutrients and trace elements.

Agriculture has been considered hazardous to soil because it causes deforestation. Before the advent of this breeding system, people used to hunt around forests. Now the forests should be removed in order for the world to supply food to people, and thus the rate of soil erosion will increase. Especially bare grounds accelerate this action the most, as well as the method of plowing, the time of planting, the nature of the crop, and size of the field will only decide the severity of erosion.

But if humans try to prevent soil from being affected by these climatic changes, there will certainly be improvements in the environment. Researchers use dendrochronological techniques in order to measure the rate of erosion. Carrara and Carroll in Colorado (1979) found that the rates of erosion soared during the past 100 years, showing 1.8mm per year nowadays, in comparison to 0.2 mm per year in the past. This action has been attributed to the settlement of cattle to the area.

Another method to figure out the rate of erosion is to check out the rate of sediment accumulation. In the Yellow River in China, the rate of sediments has been tenfold higher than that in the last few decades because of accelerated erosion. And it also proved that the European settlements (AD 1878) during the past 2000 years in the North Island of New Zealand changed the environment from indigenous forest to pasture. This last outcome (pasture) fueled the rapid rates in sedimentation, making eight to seventeen times the rates that occurred under indigenous fires.

Anyhow, forest removal by humans is the obstacle to the revival of environment. As urbanization speeds up in this era, people get rid of natural places in order to construct more buildings. This phenomenon brings debris-avalanche production in North America, for example. The amount of clear-cutting and logging roads is so substantial that erosion rate becomes multiplied hundred times more than that in the past. Table 4.1 shows the case in Oregon. || <span style="COLOR: rgb(0,17,255)"> Periods of records || <span style="COLOR: rgb(0,17,255)"> Area % || <span style="COLOR: rgb(0,17,255)"> Km2 || <span style="COLOR: rgb(0,17,255)"> || <span style="COLOR: rgb(0,17,255)"> Debris-avalanche erosion (m3km-2yr-1) || <span style="COLOR: rgb(0,17,255)"> Rate of erosion relative to forested areas || || <span style="COLOR: rgb(0,17,255)"> 25 || <span style="COLOR: rgb(0,17,255)"> 70.5 || <span style="COLOR: rgb(0,17,255)"> 12.3 || <span style="COLOR: rgb(0,17,255)"> 7 || <span style="COLOR: rgb(0,17,255)"> 45.3 || <span style="COLOR: rgb(0,17,255)"> *1.0 || || <span style="COLOR: rgb(0,17,255)"> 15 || <span style="COLOR: rgb(0,17,255)"> 26.0 || <span style="COLOR: rgb(0,17,255)"> 4.5 || <span style="COLOR: rgb(0,17,255)"> 18 || <span style="COLOR: rgb(0,17,255)"> 117.1 || <span style="COLOR: rgb(0,17,255)"> *2.6 || || <span style="COLOR: rgb(0,17,255)"> 15 || <span style="COLOR: rgb(0,17,255)"> 3.5 || <span style="COLOR: rgb(0,17,255)"> 0.6 || <span style="COLOR: rgb(0,17,255)"> 75 || <span style="COLOR: rgb(0,17,255)"> 15,565 || <span style="COLOR: rgb(0,17,255)"> *344 || || <span style="COLOR: rgb(0,17,255)"> || <span style="COLOR: rgb(0,17,255)"> || <span style="COLOR: rgb(0,17,255)"> 17.4 || <span style="COLOR: rgb(0,17,255)"> 100 || <span style="COLOR: rgb(0,17,255)"> || <span style="COLOR: rgb(0,17,255)"> || <span style="COLOR: rgb(0,17,255)">Table 4.1 <span style="COLOR: rgb(0,17,255)"> Fire is also a notable factor that causes soil erosion. Watershed experiments in chaparral scrubs of Arizona indicated that soil loss after the fire augmented the amount of soil erosion by 1000 times; before the fire, the soil loss is measured only 43 tonnes per square kilometer per year, while this conflagration destroyed 50,000 tonnes per square kilometer per year. The main cause is chaparral burning. A "non-wettable" layer in soil is hydrophobic and in the upper layer of the soil profile. If that fire resides in this place, these layers will be distilled so that they condense on lower soil layers. So the wettable layers of soil will overlie on the non-wettable one, causing severe erosion.
 * <span style="COLOR: rgb(0,17,255)"> Area type
 * 1) of slides
 * <span style="COLOR: rgb(0,17,255)"> Forest
 * <span style="COLOR: rgb(0,17,255)"> Clear-cut
 * <span style="COLOR: rgb(0,17,255)"> Road
 * <span style="COLOR: rgb(0,17,255)"> Total

The fire in this process will destroy the scrub and the root net, and change surface soil property. Then, a precipitation in low magnitude will induce extensive sheet and rill erosion, retarding vegetation recovery. This effect will increase more, and much larger precipitation will cause more erosion and de-vegetation.

Urbanization and construction is another cause of soil erosion. Wolman and Schick (1967) found out the more widely a ground is exposed to the human-living and working areas, the more equivalent many decades of natural or agricultural erosion may take place. It is the same with England, where Walling and Gregory addressed the concentration of suspended sediments and the likelihood of soil erosion.

So the outcome from this soil-related cause is the loss of major chemicals that are essential for sound ecosystems. Soil does not only consist of rocks, but also contains remained energy or chemicals crucial for the growth of plants and the purity of water. It brings about much more amount of loss than any other harmful factors do. That's why detirvores (the scientific name for biological decomposers) should be alive to help energy flow and chemical cycling of an ecosystem, and thus soil should feed them with necessary nutrients.

If people are aware of their critical living conditions, they may have to check out the soil around their home. Especially if the living area is near a megalopolis, which has an extremely high density of population and buildings, the condition of soil will almost reach the level of deterioration, because human impact is too influential for soil to keep a balance between nitrogen and carbon.

<span style="COLOR: rgb(233,43,43)">Data and Analysis:
<span style="COLOR: rgb(0,17,255)">//The experiment (growing of plants in four different types of soil) was conducted in a span of two weeks. Every two days, we went to the green house at the top floor of Pope, where we grew the plants. There, we took pictures, measured the changes in the heights of the plants, and made quick visual observations. (Just a reminder: Pot 1 contained soil from closest to human contact; pot 2, near the brook but further away from human influence; soil 3, furthest from the human civilization; and soil 4, given by Mrs. Males (potting soil).//

//General observation: Today, we planted the seeds in the pots labeled 1, 2, 3, and 4. In each plant hole we planted three small seeds. Then we watered all 36 holes with distilled water.//
 * <Day 1>**

Plant #1: Just watered.

Plant #2: Just watered.

Plant #3: Just watered.

Plant #4: Just watered.

//General observation: While soils 1 and 2 yielded quick results and had sprouts growing, soils 3 and 4 did not produce any life. We decided to wait until the next observation to see what would happen.//
 * <Day 3>**

Plant #1: Three sprouts were depicted. The one in the upper right corner barely measured up to 5 mm.

Plant #2: Three sprouts were depicted (too short to be measured).

Plant #3: No sign of life.

Plant #4: No sign of life.

//General observation: On day five of the experiment, we noticed significant growth in all soils except soil three.//
 * <Day 5>**

Plant #1: Six sprouts could be seen. The plant in soil 1 seemed the healthiest. The one in the upper right corner had the biggest leaves out of all the plants from other soils and also was the tallest of all the plants, reaching up to 12 mm.

Plant #2: Eight sprouts! Although the plants are shorter than the plants from soil 1, we observed that soil 2 yielded most number of plants.

Plant #3: Still no sign of life.

Plant #4: Two short, small sprouts grew in the upper left corner.

//General observation: There were no dramatic changes in soil 1, 2, and 3, but in soil 4, the old sprouts failed to grow, and two new sprouts sprang up.//
 * <Day 7>**

Plant #1: There were seven plants(one more than Day 5). Most were healthy and tall.

Plant #2: There were seven plants. All of them we observed to be very healthy--healthier than those plants from soil 1. These plants had taller, straighter stems and bigger leaves, however. Plant #3: One sprout could be observed in the upper left corner of the pot.

Plant #4: The two plants that had sprouted two days ago had died and one new sprout had come into life.

//General observation: The plants from soil 1 outnumbered those from soil 2. To compare the heights of the tallest plants from each soil, we used milimeters.// Plant #1: There were total eight plants. All were healthy. The tallest one from this pot measured up to 29 mm.
 * <Day 9>**

Plant #2: Here, six plants could be seen. The tallest measured up to 24 mm.

Plant #3: In soil three, there were two sprouts that could be observed (one in the upper left corner and one in the middle-row left corner.) The plants had visibly smaller leaves than the plants of soil 1 and 2. The tallest plant from this soil was 18mm.

Plant #4: In this last pot, only two sprouts could be seen. One had just begun to grow; the other one, smaller than plants from soil 1 and 2, showed much healthier characteristics than the plants from soil 3. The tallest here only went up to 15mm, almost half of the height of the tallest plant in soil 1.

//General observation: We observed the decay in the plants as evidenced by reduction of the number of plants and the shrinking of the sizes of the leaves. Nonetheless, while some plants from soil 2 had died, the remaining ones seemed to grow unlike plants from other soils.//
 * <Day 11>**

Plant #1: One died, reducing the number to five total plants in soil 1. The plant from this soil still had the tallest plant (26mm, 3mm shorter than day 9), however, the plant seemed weaker than two days prior to its picture taken. Over all, the plants from soil 1 seemed weaker (shorter and weak leaves) than those growing in soil 2.

Plant #2: We observed three plants from this soil (three had died), and these plants seemed the healthiest. One of the plants had grown four leaves, two big ones and two smaller ones criss-crossing each pair. The tallest measured up to 25 mm.

Plant #3: Only one plant had survived from the previous two days. The plant seemed to have shrunk to 12mm. The leaves of this plant were the smallest out of all the plants, and seemed to have shriveled from the last observation.

Plant #4: There was only one plant visible from soil 4. It had, surprisingly grown unlike the other plants from the other pots. It grew about 3 mm, from the last measured 15mm to 18mm. The plant here seems healthier than plant in soil 3, but less healthy than that in soil 2. The plant here very much resembles those in soil 1.

//General observation: All plants except one in soil 2 had died. While all the plants may have perished due to their short lif span, the hot temperature of the green house most probably contributed to the withering of plants that had been healthy just two days before.//
 * <Day 13>**

Plant #1: All dead. Unfortunatly, not one survived.

Plant #2: One plant in the second row had survived. (We assume that this plant has lasted longest because it grew from soil that was excavated from near the brook, and we theorize that the soil close to the bank of water gives fertility to the soil.)

Plant #3: All dead.

Plant #4: All dead. //To analyze our gathered data and thereby reiterate/ expand what was said above in our abstract, soil one produced most number of plants (seven at its max) and the tallest plant. Thus, soil one, at least from our experiment, proved to be the most fertile in the long run (since soil two produced eight plants but soon decreased in number falling short to soil one). Soil two produced plants that were the healthiest, their leaves being bigger than those of plants from other pots. Moreover, one of the plants from soil two survived the longest. Thus soil two had distinct attributes of the physical superiority and longevity. Contrary to our belief, soil three, dug up from an area furthest to human impact, produced weakest plants, by which we mean plants with smallest leaves and crooked stems. Looking at the overall growth and the eventual decay of plants from soil four, we observed that those plants were weaker than the ones from soil one and two, but still stronger than those that grew in soil three. Approximately 3 mm shorter than the tallest plant from soil three on Day 9, the tallest plant from soil four gradually catches up on its neighbor, and on Day 11 of the experiment, outgrows plant three by 6 mm.//

<span style="COLOR: rgb(233,43,43)">**Discussion:**
<span style="COLOR: rgb(0,17,255)">Our hypothesis of the soil & human impact experiment was that human impact decreases the fertility of soil. Our background information also seemed to align with our hypothesis as supported by the following quotation (from above): "But human impact disturbs the soils to become at least neutral, just like air pollution and the deposition of acid precipitation greatly influence the increasing of the level of rain acidity." Human impact often makes soil acidic as household chemicals and gas emitted by cars on highway disrupt the chemical composition of that soil nearby human habitat. Having unearthed Soil 1 from the enterance to the Flat Rock Brook, we predicted that Soil 1 will produce least successful results when we grow plants. However, this assumption soon became tested as the experiment yielded results in stark contrast to our hypothesis.

One possible explanation for the unexpected result of Soil 1 producing the largest number of plants is that the plants were planted in unusually limited areas--three seeds in each plot of soil less than a volume of one cubic centimeter. Another proposition is that the kind of vegetable plant that we chose to grow was best suited to thrive in a household environment. Experimental errors, such as unequal watering of plants and unequal distribution of soil in each plot of the pots, may also have prevented the plants to grow as they should. Then, too, we can deduce some justifications for the result by reading the "background information" provided above. We have learned that different climate affect soil and growth in different ways. As opposed to the inland soil accustomed to a more stable temperature moderated by the body water (the brook), soil one has been battered by random weather; during the experiment, the temperature changes in the greenhouse were unstable, varying from "chilly" rainy mornings to hot, humid afternoons. These sudden changes in temperature may have "thrown aback" the inland soils whereas soil 1, already used to the harsh changes in the weather, could provide quick, productive results.

<span style="COLOR: rgb(233,43,43)">**Conclusion:**
<span style="COLOR: rgb(0,17,255)">By the peculiar results of our experiment, it is obvious that human influence will not always negatively affect the environment, and there are many possible factors that lead to our results--which directly oppose the hypothesis we initially made. We can assume that there has been positive impact on the soil closest to human civilization, whether by fortunate natural occurrences that gave the soil richness in nutrients, and more isolated areas do not receive benefits. While this is all under assumption that we followed experiment procedures correctly, it is abundantly clear that the experiment has done a remarkable job of opening our eyes to different possibilities, and shows that nature and human influence are not so clear cut.

<span style="COLOR: rgb(233,43,43)">**References:**
Iowa State University, Ames, Iowa USA** <span style="COLOR: rgb(0,0,255)"> http://library.thinkquest.org/J003195F/soil1.htm <span style="COLOR: rgb(0,0,255)"> http://americangardens.suite101.com/article.cfm/basic_soil_composition <span style="COLOR: rgb(0,0,255)"> http://esa21.kennesaw.edu/activities/soil/soilcomposition.pdf <span style="COLOR: rgb(0,0,255)"> http://turfgrassmanagement.psu.edu/liming.cfm#pHdef http://www.cababstractsplus.org/google/abstract.asp?AcNo=20053119993 6th Edition. Blackwell Publishing: Massachusetts.**
 * Johnathan Sandor, C. Lee Burras, Michael Thompson
 * Andrew Goudie, The Human Impact: on the Natural Environment, Past, Present, and Future.