Size of wetland - monthly (m2)
Soil Testing
5th & 6th October
Soil testing was another of our key investigations.
We hoped to see whether the presence of the wetland had affected the nutrients in the soil below.
Comparing soil test results of wetland soil to those from the surrounding area would give us an indication whether the wetland had differing levels of:
- Ph
- Nitrates
- Phosphorous
- Potassium
We took soil samples from the same three holes we dug for the earthworm investigation. See locations on the right. Location A = Higher ground outside wetland. Location B = In wetland, halfway between edge and centre (only submerged during the wetland's peak). Location C = In the wetland centre. To carry out the tests we used a small soil testing kit (used previously to test the soil of the raised beds in the Outdoor Classroom). |
Some photos of groups carrying out the tests in the Science room.
Carrying out the tests again allowed the class to practise a wide range of science skills such as:
- Questioning
- Observing
- Predicting
- Investigating and experimenting
- Estimating and measuring
- Analysing
- Interpreting
- Recording and communicating
Results
We found quite a difference in the soil nutrients and Ph between the three samples. Ph Firstly, the wetland samples showed a lower Ph (more acidic) than the sample outside it. Sample A (outside the wetland) had a neutral ph of 7 whereas sample B and C had a Ph of 5 and 6 respectively. |
Potassium (K) The wetland soil was also lower in Potassium. The wetland samples showed a potassium deficiency with sample A achieving a 'medium' and B and C getting 'medium-low' and 'low' respectively. |
Phosphorous (P) The wetland soil was lower in Phosphorous than the soil outside it. Sample A (outside wetland) showed a P level of 'medium'. Samples B & C showed a P level of 'Very Low' and 'Low' respectively. |
Conclusion
Being more acidic, deficient in the key nutrients of Potassium, Phosphorous and especially Nitrogen, we can conclude that the wetland has had a large impact on the ecology of the area.
These conditions are not ideal for plant growth and so most plants growing here will grow more slowly or not at all. These conditions do have a knock-on effect of course and may even suit a minority of other flora and fauna which we will identify in other investigations we have planned such as the bug hunt and plant survey.
Since we included a sample from outside the wetland to compare, we can say with a good degree of certainty that the wetland (i.e the soil being submerged / waterlogged for extended periods) has caused the differences observed in nutrient and Ph values.
Some past observations now make more sense.
- During nature walks in May/June we noticed that wildflowers such as clover & meadow buttercup were not present in the wetland area. (Great site for identifying wildflowers (http://www.wildflowersofireland.net)
These conditions are not ideal for plant growth and so most plants growing here will grow more slowly or not at all. These conditions do have a knock-on effect of course and may even suit a minority of other flora and fauna which we will identify in other investigations we have planned such as the bug hunt and plant survey.
Since we included a sample from outside the wetland to compare, we can say with a good degree of certainty that the wetland (i.e the soil being submerged / waterlogged for extended periods) has caused the differences observed in nutrient and Ph values.
Some past observations now make more sense.
- During nature walks in May/June we noticed that wildflowers such as clover & meadow buttercup were not present in the wetland area. (Great site for identifying wildflowers (http://www.wildflowersofireland.net)
- In July's aerial photo the wetland area can be made out from the darker shade of green. This was because the grass in the wetland area did not grow as well as the grass outside. It had not progressed to the stage where it had a long seed head which is what gives the grass in other areas its lighter green colour in the photo here.
Questions raised: -Where have the nutrients 'gone' from the wetland soil? -If the wetland dried up would the land naturally return to normal nutrient & Ph levels? |