The Importance of Bacteria in a Garden

Many elements come into play in a garden. Plants, wildlife, humans – all come together to create an ecosystem which works as a whole. Not all of the important elements of an ecosystem are visible or evident on first look. Not least of these often overlooked elements is the bacterial life that works in plants and beneath the soil. Without bacteria, we would not have the natural cycles as we know them. Organic gardeners depend, whether they know it or not, on the action of these microscopic lifeforms.

Bacteria aid gardeners in a range of different ways. Bacteria are all around us all the time. When we think of bacteria, we tend to think of those bacteria that can do us harm and make us sick. But many bacteria are beneficial to us and to the gardens we tend. Bacteria are more important than most gardeners realise. A ton of microscopic bacteria may be active in each acre of soil. A teaspoon of soil generally contains between 100 million and 1 billion bacteria. These bacteria promote nutrient mineralisation and availability, produce plant grown hormones, and are antagonists for pests, parasites and diseases. Beneficial bacteria can play a huge role in the immune system of plants. Bacteria can also break down pesticides and pollutants.

Also amongst the most important bacteria are those involved in the nitrogen cycle. Bacteria involved in the nitrogen cycle ensure the smooth function of one of the key cycles in nature that we rely on to grow our plants. Plants need nitrogen to grow. Nitrogen is the most common element in the atmosphere, but bacteria are required for that nitrogen to be converted into nitrates – the form in which nitrogen can be taken up by the roots of plants – in the soil.

Nitrogen fixing bacteria of different types are found in soil, and living in the root nodules of nitrogen-fixing plants like legumes (peas and beans) and others. These bacteria, along with decomposing bacteria make ammonium, which is then turned to nitrites and then to nitrates by nitrifying bacteria. Denitrifying bacteria complete the cycle by converting nitrates back to atmospheric nitrogen.

Bacteria are one of the most undervalued garden 'helpers' that there is. As organic gardeners, it is important for us to understand the importance of bacteria, and to have a basic idea of how they function. As gardeners, we must do all we can to protect the soil ecosystem and to prevent the disruption of microbial life, through using 'no dig' gardening practice, and disturbing the soil food web as little as possible.