Not sure, maybe they would eventually decompose?
Ya that was my thought since they would take forever to break down they would be great for aeration and light weight unless someone can think of a reason.
I am thinking since it is carbon in a harden fiber shell great refuge for micro life. How it would effect drainage used solo might be an issue, would they need to be soaked in a High N alfalfa tea to provide additional N should they find it a readily available carbon food source? Not likely to decompose as quickly as rice hulls which I am told to soak them in alfalfa to negate any readily available N for plants that would be consumed by micro beast having a multiplication orgy.
I've believe I've accomplished this myself when I watered with a compost tea high in molasses (too much sweetness at once) that I bubbled good strong pump multiple air injectors min 36 hours. My soil did not have enough N to keep everyone happy, plants suffered, by slightly only one leaf set. Once I top dressed fish compost, water with alfalfa tea and added a little oyster shell for calcium to help in the processing of N and other nutrients. Plants recovered and once micro beast calmed down died off and produced waste this also brought balance back.
Therefore I think it is important to ensure plenty of N when adding beast or carbon sources that break down quickly and feed them like Molasses.
So ensure natural sources from mother earth are providing the N you need for if you set lose a hoard of beast or put food out for them your plants will suffer if there is not adequate N for all. I am told to maximize available nitrogen in so and avoid the robbing of nitrogen from the soil our ladies love to grow from and to keep a balance of Fungi and Bacteria to keep the ration lower than standard decomposition of C/N 30:1 or 30, instead 20 is ideal in attempting to maximize available N in soil.
So carbon loading is an art, too much you will rob N from soil to feed micro best, to little excessive is changed to ammonia.
Since the scale seem to be 20-30 when it comes to beneficial C to N rations. Where 30 to 1 at top end for decomposing where you want to heat things up and have aeration to ensure beneficial bacteria rule.
I believe closer to 20 is where we should be seeing the composition of the soil in our pots, this is the red line for vegging if you want to get exponential growth. Besides isn't vegging where we really want the N boost.
Be careful with your N sources when adding to existing soil webs especially if you enjoy and want to benefits of Fungi, too much in the soil especially from a "hot" N source like blood meal or a guano that has not be non composted. This will catalyze micro life and decomposition is accelerated into overdrive causing fluctuation in soil PH essentially cooking the soil causing fungi to dwindle and die.
Anywise if you find you over did the carbs go with N lite and bring the balance of C to N into proper range.
And wouldn't you know it as I was writing this looking for data to support my findings and to expound on them.
http://whatcom.wsu.edu/ag/compost/fundamentals/needs_carbon_nitrogen.htm
DankSwag