Studies Regarding the Fertilizing Capacity of Poultry Manure Biocomposted by Fly Larvae (Diptera: Stratiomyidae)

It's that time of the week again for another addition to the Science Blog about Black Soldier Fly (cue exciting music)!  

This week I am reviewing a paper published out of Romania on the use of BSF larval frass as a fertilizer agent- a topic not heavily covered in the literature. 

Studies regarding the fertilizing capacity of poultry manure biocomposted by fly larvae (Diptera: Stratiomyidae)

I am not very familiar with this particular journal- but given the topic, I had to take a look at the results.

My thoughts on the topic...... 
For most people that have worked with the BSF, they recognize the digestate (i.e., residue remaining after BSF larvae feed on a substrate) can be quite appealing as a potential fertilizer for soils. In our case, the residue we produce has the consistency of ground coffee with a moisture content below 20%. Both factors enhance the product in terms of packing and shipping (limited wasted space as particles are all the same size and more material in a shipment as weight is not hampered by water content).  

The challenges I have faced with BSF residue/digestate is not the consistency of the product in terms of nutrients but that the material was still very "hot" (i.e., lots of nitrogen); so, I had to be careful when applying it to plants (tomatoes in my case) as too much would resulting in burning and in some instances death.    Of course, this experience is limited to a couple of trials conducted early in my career- nothing too in-depth.  

However, over the course of the past 20 years, I have talked with BSF producers around the globe and picked up some pretty interesting anecdotal data about the potential for this material as a fertilizer. What I found most interesting besides enhanced plant growth were the claims that using the digested material as a fertilizer resulted in less insect feeding on the plants (herbivore damage).  I can imagine this being partially true (lots of promise) as the presence of insects in the vicinity of a plant can induce plant defenses (been documented for a number of insect/plant systems). So I do not think it is too much of a jump to conclude placing insect frass mixed with digested biowaste around plants would result in similar responses. Is this true with regards to BSF- well, I cannot say yes or no.  However, I can say that investigating such a topic would be of immense value to the industry, and I encourage others to tackle this topics. But if you do- I encourage you to recruit across disciplines (e.g., plant physiologist, soil scientist) to enhance your project impact.  

Author

Jeffery K. Tomberlin, PhD, a little bit of a green thumb
Director, EVO Conversion Systems, LLC
Twitter: @FliesFacility