How does the incline of a hill affect the health of the soil? Amina, Pawan, Kate, and Kathryn

How does the incline of a hill affect the health of the soil?

A little background on Nosehill Park:

Figure 1.  Nose Hill park, Calgary,
Alberta, Canada.

In order to answer this question, I studied a small hill in the forest area of Nosehill Park in Calgary, Alberta, Canada. Nosehill Park is considered a natural environment park and is the second largest park in the city of Calgary, located in the Northwest quadrant of the city. Over 198 wildlife species have been identified at Nosehill Park. The park is 11.27 square kilometres and has more than 300km of informal walking and biking trails. (Web Archive- City of Calgary, 2007) Much has been done in the past few years to preserve the park, and today it is known as a great place for nature enthusiasts and scientists. 

So what defines healthy soil? Looking back at our data from Nosehill Park in Calgary, Alberta, Canada, we chose three areas of soil to study; nitrate levels, phosphate levels and water content. In order to be able to make sense of the data collected from Nosehill, we have to have values that give us reference points as to what healthy and unhealthy levels of the nutrients are.

Nitrates: A good level of nitrates present in soil to help plants grow the best that they can is around 9.99mg/l  to 24.97mg/l. (Interpretation of Soil Results, 2003)

Nitrate Content in Soil Samples 5cm below Surface at Nosehill Park

Soil Sample Distance from bottom of Transect (m)	Nitrate Content NO3-  (mg/l)
0.00	22.00
7.00	20.00
14.00	14.50
21.00	10.00
28.00	7.00
35.00	4.50
42.00	5.50
49.00	5.00

Table 1:Nitrate content in soil samples taken from 8 different spots each spaced 7.00m apart along the transect 5.00cm deep into the ground in Nosehill Park, Calgary, Alberta, Canada.

Figure 2.  Nitrate test results
interpretation card. 

The results from Nosehill Park show that the Nitrate levels in the soil at the top of the hill at the 49.00m mark are at approximately 5mg/l. This value compared with our healthy nitrate value of 9.99mg/l to 24.97mg/l shows that the nitrate values at the top of the hill are low and therefore not very healthy soil nitrate values. As the distance to the bottom of the transect becomes less, the nitrate content in the soil goes up. This means that the nitrate content in the soil is getting closer to a healthier value of 9.99mg/l to 24.97mg/l. At the very bottom of the transect at 0.00m with an incline of 0 degrees, the soil nitrate content is approximately 22mg/l. This value is considered to be a relatively healthy value compared to our reference point.  Table 1 shows us how the nitrate content in the soil increases as the distance to the bottom of the transect decreases.

Phosphates: A good level of phosphates in the soil to help plants grow the best that they can is around 0.34mg/l to 0.39mg/l. (Manitoba Agriculture, 2010)

Phosphate Content in Soil Samples 5cm Below Surface at Nosehill Park

Soil Sample Distance from bottom of Transect (m)	Phosphate Content PO43- (mg/l)
0.00	0.50
7.00	0.40
14.00	0.20
21.00	0.20
28.00	0.30
35.00	0.15
42.00	0.10
49.00	0.10

Table 2:Phosphate content in soil samples taken from 8 different spots each spaced 7.00m apart along the transect 5.00cm deep into the ground at Nosehill Park, Calgary, Alberta, Canada.

Figure 3.  Phosphate test resluts
interpretation card.

The results from Nosehill Park show that the phosphate level at the top of the hill at 49.00m was approximately 0.1mg/l. This value compared with out healthy phosphate value of 0.34mg/l to 0.39mg/l shows that the phosphate levels are low at the top of the hill. This is the same as the nitrate levels at the top of the hill as well. As the distance from the bottom of the transect becomes less, the value of phosphates in the soil goes up. At 0.00m from the bottom of the transect with an incline of 0 degrees, the phosphate level is at approximately 0.5mg/l. This is a bit higher than our healthy value, but still shows that the amounts of phosphates increase near the bottom of the hill and decrease at the top of the hill. The fact that the amount of phosphates found in the soil at the bottom of the hill is higher than the healthy value also forces us to realize that the incline of a hill can also create an excess of nutrients at the bottom of the hill. If this level gets too high, especially with the use of things such as fertilizers, it can make the soil at the bottom of the hill much less healthy than the soil at the top of the hill.

What is the importance of healthy nitrate and phosphate levels in the soil?

Nitrates (NO₃^-) and nitrites (NO₂^-) are chemical compounds containing atoms of Nitrogen and Oxygen. Nitrates and nitrites occur naturally in the earth, and are one of the most important factors when it comes to the growth of plants. This is because Nitrites and Nitrates provide the element nitrogen for the plant, which is used in the process of making amino acids. (Free Drinking Water, 2010) Amino acids are then used to make proteins and enzymes within organisms. Nitrogen is one of the most important elements for organic life, and it is found naturally in soil in the form of nitrates.

Unlike the element nitrogen, Phosphorus is only found in one form in nature; phosphates (PO₄^3-). Phosphorus is used in both the metabolism processes (the organic processes (in a cell or organism) that are necessary for life (WordNet, 2010)) and for photosynthetic processes which have to do with producing food for the plant. (Free Drinking Water, 2010)

Water Content: A good level of water content available in the soil for plants to use is around 15%. (Manitoba Agriculture- Water use and Moisture Management, 2010)

Water Content

Soil Sample Distance from bottom of transect (m)	Water content by mass (%)
0.00	20.23
7.00	16.07
14.00	11.47
21.00	10.77
28.00	4.8
35.00	6.72
42.00	6.36
49.00	2.68

Table 3: Water Content Levels at 8 different spots each placed 7.00m apart along the transect 5.00cm deep in Nosehill Park, Calgary, Alberta, Canada.

The results from Nosehill Park show that the water content at the top of the hill at the 49.00m mark is very, very low compared to our healthy soil moisture level value of around 15%. However, as you get closer to the bottom of the transect, the percentage of water available in the soil increases. At 7.00m from the bottom of the transect there is a soil water content value of 16.07%, which is very close to our healthy value of 15% water content. At the bottom of the hill at 0.00m, the water content percentage is 20.23%, which is still a relatively healthy value and is much closer to our healthy value of 15% than the 2.68% seen at the top of the hill. 

How does the incline of a hill affect the health of the soil?

Figure 4.  Forest area in Nose Hill
Park, Calgary, Alberta, Canada.

After choosing three different measures of determining healthy soil, collecting data from Nosehill Park and researching healthy values to come up with answers, we can finally come to a conclusion to answer the initial question for this research project; How does the incline of a hill affect soil quality? The nitrate test showed us that as you go further up the hill, the nitrate value in the soil decreases. This was the same for the phosphate level which decreased as you went further up the hill. The results for both the nitrate test and the phosphate test were the same due to the water content levels along the hill. The water content percentage was much higher at the bottom of the hill than at the top of the hill, same as both the nitrogen and the phosphates. This can be explained by the flow of water down the hill carrying the nitrates and phosphates with it, and creating a larger accumulation of nitrates and phosphates near the bottom part of the hill. Since the nitrates and phosphates are being washed away from the top of the hill with the water, it makes the soil at the top of the hill less healthy than the soil at the bottom of the hill.

Conclusion:

The soil found at the bottom of a hill will be healthier than the soil found near the top a hill for the most part unless the leaching of nutrients down the hill with the flow of water creates an excess of nutrients at the bottom of the hill which is then unhealthy for plant growth. 

References

The City of Calgary: The Nosehill Trail and Pathway Plan, Retrieved on October 24^th, 2010 from http://web.archive.org/web/20070930221148/http:/www.calgary.ca/portal/server.pt/gateway/PTARGS_0_2_780_237_0_43/http;/content.calgary.ca/CCA/City+Hall/Business+Units/Parks/Parks/Natural+Environment+Parks/Locations/Natural+Areas+in+NW+Calgary/Nose+Hill+Park/The+Nose+Hill+Trail+and+Pathway+Plan.htm

Interpretation of Soil Test Results, March 2003, Retrieved on October 24^th, 2010 from http://www.extension.iastate.edu/Publications/PM1310.pdf

Government of Alberta: Manitoba Agriculture, Retrieved on October 23, 2010 from http://www.gov.mb.ca/agriculture/soilwater/nutrient/fbd02s16.html  

Free Drinking Water, 2010, Retrieved on October 23, 2010 from http://www.freedrinkingwater.com/warranty.htm

Word Net: Princeton University, Retrieved on October 24, 2010 from

 http://wordnet.princeton.edu/