In my research on soil algae I found that over a period of 3 months the soil pH dropped by 0.6-0.8 units and the algae grew very well. However I did a correlation between the abundance of algae and the respective soil pH and found a positive correlation between, i.e. the more algae there were, the higher the soil pH. I just don't understand why the overall soil pH is dropped from start of the test?
Is 0.6-0.8 considered large in soils science? The increase in pH could be explained by the uptake of CO2, especially when abundance is high. Perhaps a decrease at the start of the experiment could be due to the release of organic acids by breakdown or microbial respiration. It depends a bit what the pH was before the study started, the variability before the pH increased and how high the pH was at the end of the study. A graph would be nice, you can remove if from researchgate before publication anyhow.
the initial pH is around 7.53, and the final pH is around 6.75 after 3 months soil algae growth. I have different soil treatments, like soil compost, biochar and clay. however even in the control (the washed sand from river bank) without any treatment, the pH also dropped...
Hi
These two papers would be useful for you:
Article The biostimulating effects of viable microalgal cells applie...
Article Application of a microalgal slurry to soil stimulates hetero...
My initial expectation would be that pH on clay would be less affected due to bound ions, leading to ion exchange buffering some of the effects. Then again clay is not as permeable as compost. On the other hand, clay could also enhance growth of the algae due to the bound ions.
Sand would be the substrate type on which I would expect to observe the least amount of "effects", since it would be more "inert" compared to the other substrate types. It has relative little bound ions (no strong charged surface area). I would expect the largest variation of pH on this substrate type. Then again, due to the lower amount of bound ions, growth could be limited.
Did you perform a digestion/destruction of the sediment for elemental analysis? Or, did you determine bio-available phosphorus (e.g. via Olsen-P method)?
Omer Lekesiz
I did the pH measurement late in the afternoon in the Lab under the normal light of the Lab. According to your opinion, the lower pH might due to the respiration of the algae (whose effect might greater than the photosynthesis because of the weak light in the afternoon)?
Hey guys:
pls have a look of the figure:
the line indicates the pH-start and the columns stand for the pH-after.
the X-axis are the three treatments: biochar, clay, and compost as well as a pure sand as control.
the Y-axis is the value of pH
two colors stand for green algae and field algae (which is mostly cyanobacteria), applied on the surface of the soil. the whole experiment last for 3 month under greenhouse condition (12/12 light/dark).
It may be caused by the photosynthesis of algae. Oxygen is produced in this process. As the pH of the soil is suitable for algal growth, using it the plant may grow very fast. But at the same time, for the generation of oxygen, the pH may change.
If you differently, please give me your opinion. I have worked on aquatic algae. I am reedy for this interesting discussion.
In my opinion and as other RG colleagues mentioned in comments here, this is not a big change to worry about, but should be controlled time to time continuously and this observed decrease in pH is the consequence of the growing circumstances of that soil algae and I think it totally depends on photosynthesis process and soil respiration. In my opinion there is a compatible range of soil pH which is tolerable for soil algae, which may differ in different genera.
To me the results make sense. On sand, pH starts high and ends low because limited buffer capacity (at least distance between start and end (mean?) is large). On clay, this distance is smaller and at the end of the experiment ends higher than sand, although pH at the start seems biased (at leas for the green algae). Interesting is that the pH ends highest on biochar substrate, no idea why without knowing the composition.
If you have abundance of algae and pH over time a simple scatter-line plot could reveal some differences? Time on the x-axis, pH on the first y-axis and abundance on the second y-axis, where each treatment is an individual line. This can sometimes be confusing so a 3D plot x=time, y=pH and z=abundance might also work (depends on how it looks like). Otherwise you could also separately plot time versus pH or abundance.
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