Experiment 2
This experiment will focus on Eucalyptus oils, and try to reproduce the allelopathic effects with different methods associated with the oils.
Eucalyptus oil added to potting mix will be compared to a control, a pot containing a fresh pulverized leaf mulch and a pot containing the strained water from the pulverized leaf mulch.
The five pots are as follows:
1./ High concentrated Eucalyptus Oil (high C Oil)
1ml of Eucalyptus oil is mixed with 80 grams of potting mix. Watered with 75ml of clean tank water.
2./ Low concentrated Eucalyptus Oil (low C Oil)
1 heaped teaspoon of the above (High C Oil) soil mix is added to 80 grams of fresh potting mix. Once mixed in, 1 teaspoon is returned back to the high concentrated mixture to return both to same volumes. Watered with 75ml of clean tank water.
3./ Fresh Leaf Mulch
100 grams of fresh Mountain Grey Gum leaves were added to a bottle with 465 grams of clean tank water. The leaves were left to soak and ferment for 24 days. 10 grams of leaves were then place into a food processor and pulverized in about 75 mls of the soak water. The solids were filtered out to produce a green acidic water and fresh gum mulch (see fig 1). The fresh gum mulch was mixed in with 80 grams of potting mix to produce a 'Fresh Mulch' pot.
4./ Fresh strained gum water.
The water from the above was carefully strained through paper towel. (see fig 2) The water was found to have a an acidity of 4.4 and electrical conductivity of 2.4 mS/m (millisemens per metre). This water was used to water 80 gms of potting mix soil to create this gum-water pot.
5./ Control
This pot is 80 grams of plain potting mix watered with 75mls of clean tank water.
Fig 1. fresh fermented gums leaves after pulverized in food processor, added to mixture for pot #3
Fig 2. Water strained from above process, and used for pot #4
figure 1. Chicory and Barley seeds after 5 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting Mix
Click above thumbnails for larger image.
After a few days some differences are beginning to emerge. The high concentrated oil mix (1ml per 80gms) is looking quite toxic. The chicory in this mix has been slow to germinate, and there may be some early indication of stress in them. The barley seeds look like they will not germinated at all. The pot with a low concentration of oil (~0.02ml per 80gms) is showing no issues compared to the control.
The pot with 10 gms of pulverised leaf mulch is slightly delayed in germination and growth compared to the control (#5), but the barley and chicory in them is not looking particularly stressed. As per experiment 1, the pot with highly acidic leaf water extract has delayed germination and growth.
figure 2. Chicory and Barley seeds after 10 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting Mix
Click above thumbnails for larger image.
On day 10, the barley seeds in the high-concentrated oil mixture have not sprouted, only one has shown a root. The oil appears to have completely stopped them germinating. The chicory in this pot is sprouted, but growing very slowly compared to all other pots, even those in the highly acidic gum-water pot. The roots on many of these chicory appear weak and sometimes shriveled. There is no evidence of roots reaching the base of the pot like in all the other pots.
There is also mold growing around the barley grains.
figure 3. Chicory and Barley seeds after 15 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting Mix
Click above thumbnails for larger image.
Day 15: Surprisingly 2 barleys have finally sprouted in the high concentrated oil mix. The chicory has certainly grown since last photographing, and roots are showing at the base of the pot. Apart from the significantly reduced growth, there is also far more mold growth in the high concentrated mix, and not just around the barley grains. The other pot with similar amount of mold growth is the one containing fresh fermented gum leaves. It seems very possible that the white mold is digesting the oils.
This development points to the possibility that the toxic effect of the oils are being reduced by the molds breaking them down. The pot does not smell like eucalyptus oil, so it can be assumed the volatile components have evaporated also. If the toxic effects have reduced over such a short period then the implications are significant and suggest much complexity to the toxicity effect.
Field observations show that soil under gums remain toxic for very long times even after gums have been removed. A few pulverized leaves in a pot of fertile potting mix has very little or no visible effect, which would suggest that it is only after significant accumulation of toxins in the soil that the problem becomes significant - and yet, this experiment is suggesting that toxins may be easily broken down quickly, and therefore unable to accumulate in soils easily.
We will need to retest the high concentrated oil mix again with a fresh mixture to see if indeed it has lost toxicity, and if so, we will have to consider the confusing implications.
So far I have not seen significant allelopathic effects in these high-fertile potting mixes that matches what can been in highly acidic heavy clays under gums. It seems that the growth inhibition in soils under and near gums is not just from oils, but a combination of several factors.
figure 4. Chicory and Barley seeds after 18 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting Mix
The pots were re-watered before this last sampling, and the results continue as before. The pot with the high concentration of oil seems to be coming to life suggesting the toxins in the soil are not as high as they were originally.
Eucalyptus oil added to potting mix will be compared to a control, a pot containing a fresh pulverized leaf mulch and a pot containing the strained water from the pulverized leaf mulch.
The five pots are as follows:
1./ High concentrated Eucalyptus Oil (high C Oil)
1ml of Eucalyptus oil is mixed with 80 grams of potting mix. Watered with 75ml of clean tank water.
2./ Low concentrated Eucalyptus Oil (low C Oil)
1 heaped teaspoon of the above (High C Oil) soil mix is added to 80 grams of fresh potting mix. Once mixed in, 1 teaspoon is returned back to the high concentrated mixture to return both to same volumes. Watered with 75ml of clean tank water.
3./ Fresh Leaf Mulch
100 grams of fresh Mountain Grey Gum leaves were added to a bottle with 465 grams of clean tank water. The leaves were left to soak and ferment for 24 days. 10 grams of leaves were then place into a food processor and pulverized in about 75 mls of the soak water. The solids were filtered out to produce a green acidic water and fresh gum mulch (see fig 1). The fresh gum mulch was mixed in with 80 grams of potting mix to produce a 'Fresh Mulch' pot.
4./ Fresh strained gum water.
The water from the above was carefully strained through paper towel. (see fig 2) The water was found to have a an acidity of 4.4 and electrical conductivity of 2.4 mS/m (millisemens per metre). This water was used to water 80 gms of potting mix soil to create this gum-water pot.
5./ Control
This pot is 80 grams of plain potting mix watered with 75mls of clean tank water.
Fig 1. fresh fermented gums leaves after pulverized in food processor, added to mixture for pot #3
Fig 2. Water strained from above process, and used for pot #4
figure 1. Chicory and Barley seeds after 5 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting MixClick above thumbnails for larger image.
After a few days some differences are beginning to emerge. The high concentrated oil mix (1ml per 80gms) is looking quite toxic. The chicory in this mix has been slow to germinate, and there may be some early indication of stress in them. The barley seeds look like they will not germinated at all. The pot with a low concentration of oil (~0.02ml per 80gms) is showing no issues compared to the control.
The pot with 10 gms of pulverised leaf mulch is slightly delayed in germination and growth compared to the control (#5), but the barley and chicory in them is not looking particularly stressed. As per experiment 1, the pot with highly acidic leaf water extract has delayed germination and growth.
figure 2. Chicory and Barley seeds after 10 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting MixClick above thumbnails for larger image.
On day 10, the barley seeds in the high-concentrated oil mixture have not sprouted, only one has shown a root. The oil appears to have completely stopped them germinating. The chicory in this pot is sprouted, but growing very slowly compared to all other pots, even those in the highly acidic gum-water pot. The roots on many of these chicory appear weak and sometimes shriveled. There is no evidence of roots reaching the base of the pot like in all the other pots.
There is also mold growing around the barley grains.
figure 3. Chicory and Barley seeds after 15 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting MixClick above thumbnails for larger image.
Day 15: Surprisingly 2 barleys have finally sprouted in the high concentrated oil mix. The chicory has certainly grown since last photographing, and roots are showing at the base of the pot. Apart from the significantly reduced growth, there is also far more mold growth in the high concentrated mix, and not just around the barley grains. The other pot with similar amount of mold growth is the one containing fresh fermented gum leaves. It seems very possible that the white mold is digesting the oils.
This development points to the possibility that the toxic effect of the oils are being reduced by the molds breaking them down. The pot does not smell like eucalyptus oil, so it can be assumed the volatile components have evaporated also. If the toxic effects have reduced over such a short period then the implications are significant and suggest much complexity to the toxicity effect.
Field observations show that soil under gums remain toxic for very long times even after gums have been removed. A few pulverized leaves in a pot of fertile potting mix has very little or no visible effect, which would suggest that it is only after significant accumulation of toxins in the soil that the problem becomes significant - and yet, this experiment is suggesting that toxins may be easily broken down quickly, and therefore unable to accumulate in soils easily.
We will need to retest the high concentrated oil mix again with a fresh mixture to see if indeed it has lost toxicity, and if so, we will have to consider the confusing implications.
So far I have not seen significant allelopathic effects in these high-fertile potting mixes that matches what can been in highly acidic heavy clays under gums. It seems that the growth inhibition in soils under and near gums is not just from oils, but a combination of several factors.
figure 4. Chicory and Barley seeds after 18 days
1./ High Concentrated Oil Mix
2./ Low Concentrated Oil Mix
3./ Fresh leaf mulch mix
4./ Acidic Gum Water
5./ Clean Potting MixThe pots were re-watered before this last sampling, and the results continue as before. The pot with the high concentration of oil seems to be coming to life suggesting the toxins in the soil are not as high as they were originally.
