Understanding the soil food web

Without bacteria, fungi, protozoa, earthworms, etc, maintaining a good soil condition would be difficult

Published: 12th February 2020 06:52 AM  |   Last Updated: 12th February 2020 06:52 AM   |  A+A-

Express News Service

BENGALURU: As a gardener, your life can become a lot simpler if you spend time understanding the soil food web, and the role it plays in helping your plants grow. Good-quality soil that supports plant growth is teeming with life – bacteria, fungi, protozoa, nematodes, earthworms and more. I think of these as an army that works for you, in helping your plants grow and thrive. These organisms provide nutrients to your plants, maintain soil structure by loosening it continuously and defend against pests and pathogens.
Let me try and explain how the soil food web works, so you can harness power of this army better.

The story starts with plants themselves. With the help of photosynthesis, they produce sugars that they exude through root hairs. These root exudates attract beneficial bacteria and fungi to the area near root hairs, and they begin their win-win relationship with the plants. Many of these bacteria and fungi are eaten by larger organisms like nematodes and protozoa, and in the process, release nutrients which the plants absorb. An easy way to visualise this is to think of bacteria and fungi as bags of fertilisers, which are punctured by larger organisms to spread the nutrients and make them available for plants.

The most amazing aspect of all this is that, individual plants control what sort of bacteria and fungi to attract, based on their particular nutrient and defense needs, by modifying the chemicals they exude at different times. So, your army has its mini-generals too, and they are the plants themselves.

These organisms present in soil also play a key role in improving your soil structure. The bacteria produce a slime so that they can attach themselves to soil particles, and this bacterial slime binds together soil particles into larger structures. This helps make your soil porous, which is important because it lets root hair breathe and have access to water vapour. The nematodes and protozoa, which ate the bacteria and fungi, they are in turn eaten by arthropods like earthworms. And, earthworms travel through the soil by creating tunnels. This again improves soil structure and aeration.

Bacteria and fungi also play a role in defence against pathogens. The bacterial slime and the fungal webs created act as physical barriers to pathogens. Some of them even produce vitamins and antibiotics to help maintain and improve plant health. (Remember penicillin? It’s produced by a fungus!)Here’s the bad news.  When you use chemicals fertilisers and pesticides, you end up killing much of this life, and hence you lose your own army. And then you start seeing your soil getting compacted, your plants unable to absorb nutrition even if you are supplying fertilizers, pest and diseases, and so on. So, you must avoid chemicals if you want to leverage the power of your army of microbes.

In order to get life back into your soil and establish a thriving soil food web so that your work is minimised, I recommend using compost extensively along with compost tea. You prepare compost tea by putting some compost along with water, some jaggery, and bubbling air into it continuously for 48 hours. The sweet smelling liquid produced by this process has a very high density of beneficial micro-organisms. Apply this to your soil, and make sure there is enough mulching to let these micro-organism thrive, and your army will be ready to roll and perform their duties 24x7 for you.The author is the CEO, Farmizen, a platform connecting organic and natural farmers to urban consumers with same-day farm to fork delivery.


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