Inoculants

[redback]

Given that bacteria, fungi, algae, lichen, mosses and ferns all predate any form of seed bearing plant ( spermatophytes and gymnosperms). I think you may be mistaken; would be interested to see any peer reviewed scientific evidence you have for this.

A friend is growing in a raised bed with the soil sitting on top of plastic sheeting. The previous owners have added soil from unknown sources. So, we are wondering if the soil's natural microbial level is missing.
Adding diluted liquid seaweed has lifted his pumpkin visibly. Although he has had some good crops his soil is depleted. It's no different to growing in pots but in this case, we are wondering if the full microbiome can be established in beds detached from the natural ground. Worms can be introduced and some of the inoculants already mentioned in this thread will surely bring some bacteria and fungi but does detachment lower plant resilience in some way?
In answer to @Nigeij's question above - yes microbes are the first single celled lifeforms on earth but that hasn't prevented them from being present in every lifeform that has evolved since.

 

[Meadowlark]

A friend is growing in a raised bed with the soil sitting on top of plastic sheeting. The previous owners have added soil from unknown sources. So, we are wondering if the soil's natural microbial level is missing.
... but does detachment lower plant resilience in some way?

Yes, I believe it does. What is the purpose of the plastic (yuk!) sheeting?

Many veggie plants have surprisingly deep root systems...far deeper than most realize especially in good quality soil. Blocking that natural tendency is not a good thing.

Somehow, I believe that plants can sense that blockage even if roots aren't that deep and certainly the microbiome is not positively enhanced with the plastic presence.

 

[redback]

Yes, I believe it does. What is the purpose of the plastic (yuk!) sheeting?

The sheeting was probably placed to avoid weed growth. It is currently helping in the drought because the ground is soaking up a lot of water and this stops the drainage to the water table. It will cause drainage problems in winter.

 

[Meadowlark]

The sheeting was probably placed to avoid weed growth.

IMO, dealing with weed growth would be far superior to underlayment of plastic sheeting.

 

[redback]

IMO, dealing with weed growth would be far superior to underlayment of plastic sheeting.

You can view it as planting into a plastic pot. I'm not happy with the isolation from the ground because there is no interaction with migrating worms or soil life in general so we will maximize soil life in the raised bed and see if there are good result with side drainage.