Let's Get to the Root of This...

by Kevin
(UK)

I have my main crop of veg and flowers from which I take my main food supply and flowers for the missus and home. After I harvest I shake the root balls which leaves me with used compost mixture with a fairly generous helping of roots.

Now, I could make a Scotsman blush - I want to re-use that compost and roots for secondary grows that are not important to me - such as potato bins. I believe that while the compost is used, it is not 'spent' besides which I would be adding some fertilizer in anyway. I am also aware of quick green crops that are designed to be chopped back into the compost mixture specifically to add nitrogen, which is another idea I'm planning on.

So my question is simple. Would dead/dying roots cause a problem for new growth? I hope you're going good, man ;-) Thanks for all your hard work in answering and posting all the queries you do.)

Answer: Kev- for the most part, a small percentage of dead roots in the soil will not cause any problems. This is especially true when re-using the compost in a second crop that is dis-similar from the first crop. Where you begin to run into questionable territory is when you keep re-using the compost and/or soil with bits of live roots and plant material in it AND you also keep planting the same type of plants into the re-used soil.

What happens when you keep adding bits of live plant material to the soil is that (eventually) some pathogens that happen to really like that particular plant material are going to come across your soil with all the bits of live roots mixed in it still, and those pathogens are going to make that soil into their home. If growing peppers, than re-using the soil on potatoes, this might not be such a big problem....the pathogens that attack peppers probably will not have any effect on the potatoes.

Once the soil is infected with a pathogen that attacks peppers, however, that soil will kill peppers every time you try to grow any peppers in it. This is true for any particular crop. If you constantly try to re-use soil again and again, always planting the same crop again and again, the soil is always pre-disposed to turn against those varieties for the same reasons. This is one of the two main reasons why farmers practice crop rotation.

So, to keep your garden as trouble free as possible, either compost the re-used soil a little bit before actually re-using it, or else be sure keep the principle of crop rotation in mind when re-using the soil, and you should be doing very fine. Happy Growing!