I figured it was about time I posted an update on my cucumber-growing (with vermicompost) experiment. If you happened to miss the first installment, here is the link: “A Tale of Three Vermicomposts“. I’m actually quite surprised I still have any of my plants left, to be totally honest. Apart from dealing with seedling-munching chipmunk early on (I kid you not), I’ve also been battling with very hot, dry weather (by our standards, anyway). Speaking of which, I actually did end up giving up on the small passion-flower seed growing experiment since it was just too difficult to keep the three small pots moist.
The results of the other two experiments have been quite interesting so far. I am definitely seeing some strong evidence to indicate that not all vermicomposts are created equal! Before I elaborate, let me quickly point out that the following results should IN NO WAY serve as a reflection of the quality of the vermicomposting system these vermicomposts were created in. There are MANY different factors that can play a role in helping to create a top notch vermicompost, such as the type of feedstock, frequency of feeding, quantity of worms present in the system etc. Obviously the type of bin/bed used will still be an important factor – I just don’t want people assuming these types of systems are no good for producing decent vermicompost simply based on my results. I’ll definitely discuss this a bit more once I’ve shared the results.
A quick word or two about the chipmunk munching (lol) before we dive in here. The seedlings in the larger (100% vermicompost, with one black earth control) pots were not harmed at all, but in the soil + vermicompost experiment I ended up with only two seedlings in the WF-360 treatment and two seedlings in the manure-vermicompost treatment (the other two treatments were unharmed). Since this entire project is mostly for fun, I don’t think I’ll lose any sleep over it. lol
OK – the “results”…
For starters, it seems as though my own hunch about 100% vermicompost potting mixes not being the best choice has some validity. I guess you could say this is based on more than a “hunch”, though, since it mirrors some of the findings in the academic literature. Of the three vermicomposts, the manure vermicompost appears to be the “best” in terms of supporting plant growth on its own, and may be even better than the black earth soil as you can see in the first image below.
The WF-360 and Worm Inn vermicomposts did not fare quite so well. The plants growing in the WF-360 vermicompost actually ended up getting killed off by some sort of disease (seemed to be some form of “damping off”). The Worm Inn vermicompost plants survived, but as you can see below they seem to be suffering from some sort of deficiency (likely low nitrogen).
Based on the look of the plants in the soil + vermicompost experiment (below), I think it’s safe to say that including vermicompost as part of a potting mix (with soil etc) is likely a better strategy! Interestingly enough, the plants seem to be more robust in all the treatments with vermicompost than in the black-earth-only control pots. That being said, there IS still some evidence to suggest that the Worm Inn and WF-360 vermicomposts contain some compounds (or disease organisms) that are negatively affecting plant growth. Some of the leaves in these treatments appear to be stunted and/or to have some blemishes on them.
In all honesty, the results (so far) really don’t surprise me all that much when I think back to how the WF-360 and Worm Inn systems were managed prior to harvesting the vermicompost! Both systems were badly neglected, and the resultant vermicompost in both was likely derived largely from the processing of shredded cardboard – rather than lots of rich food wastes.
According to various research studies conducted at Ohio State University (the “Mecca” of academic research in this field) manure vermicomposts have always tended to perform better than those created from other materials, so I’m also not TOO surprised to see this one outperforming the others (especially considering how the other ones were made).
What I’d like to do now is transfer the soil + vermicompost plants to larger pots (with more of the same mix they are in), and add some slow-release fertilizer tablets to each of them to see how they respond. One of the important findings in the academic literature has been the fact that vermicomposts appear to provide plant-growth-promoting benefits that go above and beyond simple fertilization, so it will be interesting to see if the plants in the vermicompost treatments continue to outperform those in the black earth soil.
I’d like to get to the point of actually growing cucumbers if I can, since it will be even more interesting to see if the presence of my vermicomposts helps to improve yields at all.
Should be fun. Stay tuned!