Recently a bachelor student of Physical Geography will be doing her thesis in anthroponics and I will be supervising her thesis. For this reason, we will be redoing the trial with wood ash and cucumbers to confirm the initial results we obtained. Since her thesis will be written in swedish, I will write a technical report in english as well. For now, we have just placed the seedlings:
This time, we have brought the pH down to the 5,5 – 6,5 range suited for cucumbers before placing the seedlings, to prevent any shock to the plant. In the last trial (10/01/16 – 29/03/16), before removing the best performing cucumber after 79 days (from system 3, which had 72g of wood ash), I also conducted a general chemical test to the assess the water quality. Here you can see the overall size of the cucumber and some of the deficiencies. Total length was about 140cm, though there were several branches.
Based on some observations of interveinal chlorosis in the leaves and 0,00mg/L of Fe in water, it was obvious the plant had an iron deficiency. The concentration of phosphorus was also below the recommended level, though there were no clear signs of deficiency. There seemed to be some potential signs of sulfur deficiency given that upper leaves remained small, curled downwards and with serrated margins, but I do not have the reagents or the resources to test sulfur.
With this new trial, besides our own limited chemical analysis, we hope to get the support of her university to do some more depth tests, such as tissue analysis of the leaves, and water quality by the university laboratory. However, it seems the tests are very expensive and even the university cannot afford to do all the ones that we wanted. A lack of proper laboratory analysis of anthroponics systems seems to be a recurring theme given that there is still very little academic interest in the topic at the moment.
Regardless, our first water quality analysis before adding the seedlings seems to indicate an abundance of all macro and micronutrients with the notable exception of Iron, which had 0,00mg/L in all three systems. Like aquaponics systems, Iron is a common micronutrient that is lacking and must be supplemented. It seems after we have ran this trial that the next focus will be to find a way to supplement Iron in a sustainable way, and possibly any other nutrients we may find lacking.