The phytometer is a method that uses an aquatic plant to test the ability of a sediment or nutrient solution to grow rooted plants.
This is a paper I did as part of class lab. It is essentially independent of any CO2 , light or water column effects as the plants are generally grown in a green house or terrarium and humidity levels can be adjusted to suit various aquatic plant species.
Most all aquatic plants are amphibious, they have an emergent stage. They possess the ability to live above the water's surface. Using this trait allows any aquarist to repeat similar methods to gauge and compare different sediments or nutrients without deal with having to maintain many aquaria, CO2, etc, water column nutrients, algae.
This provides much more reliable results for comparing.
It does tell differences between plants, treatments with respect to CO2 however.
There is no mixing or transfer of nutrients from each flask and these can be rather small and many replicates of each treatment may be done for better "statistical power", generally 6-8 is enough to see significant differences between treatments.
In any such "test", having a baseline for comparison is critical. Unfortunately, most aquarist have little idea how to provide a control.
In this test, we used DI water and hoalgand's modified solution for zero nutrient and the upper bound non limiting nutrient solutions.
We assumed that all other nutrient treatments tested would fall somewhere in between these two extremes. This assumption is reasonable and logical.
The measure of comparison is relative to these two measurements.
Hobbyists will not likely be able to easily do the N and P tissue content, however, the analysis could be sent to agriculture lab for such analysis for a fee.
However, most hobbyists can measure stem, leaf, dry weight biomass etc if they tried and used a good 0.001gram scale.
You could also just ask for one nutrient, say Fe for seeing what concentration or type of chelator is taken up best etc.
Then see what actually got into the plant.
Regards,
Tom Barr
This is a paper I did as part of class lab. It is essentially independent of any CO2 , light or water column effects as the plants are generally grown in a green house or terrarium and humidity levels can be adjusted to suit various aquatic plant species.
Most all aquatic plants are amphibious, they have an emergent stage. They possess the ability to live above the water's surface. Using this trait allows any aquarist to repeat similar methods to gauge and compare different sediments or nutrients without deal with having to maintain many aquaria, CO2, etc, water column nutrients, algae.
This provides much more reliable results for comparing.
It does tell differences between plants, treatments with respect to CO2 however.
There is no mixing or transfer of nutrients from each flask and these can be rather small and many replicates of each treatment may be done for better "statistical power", generally 6-8 is enough to see significant differences between treatments.
In any such "test", having a baseline for comparison is critical. Unfortunately, most aquarist have little idea how to provide a control.
In this test, we used DI water and hoalgand's modified solution for zero nutrient and the upper bound non limiting nutrient solutions.
We assumed that all other nutrient treatments tested would fall somewhere in between these two extremes. This assumption is reasonable and logical.
The measure of comparison is relative to these two measurements.
Hobbyists will not likely be able to easily do the N and P tissue content, however, the analysis could be sent to agriculture lab for such analysis for a fee.
However, most hobbyists can measure stem, leaf, dry weight biomass etc if they tried and used a good 0.001gram scale.
You could also just ask for one nutrient, say Fe for seeing what concentration or type of chelator is taken up best etc.
Then see what actually got into the plant.
Regards,
Tom Barr
Maybe we could grind up the plant mass and titrate the Fe out