Use plants to fertilise and repair your soil

Nature heals itself and certain plants can help restore soil health. Plants have abilities that improve soil structure, enrich it with nutrients and encourage healthier microbial life.

These range from deep rooted species that break up compacted and contaminated soil to nitrogen fixing plants. Many of these plants are low maintenance and thrive in harsh conditions.

Healthy soil is the foundation of our ecosystems, vital to grow our food to nourish us and an important ally in our fight to restore our planets health.

In our gardens, plants are continually feeding from the soil, depleting the nutrients leading to reduced productivity and planet's health.

The best plants for increasing soil fertility are those that produce lots of biomass which can be worked into the soil, and nitrogen fixing plants. Nitrogen fixing plants are those plants that have root nodules, which house the symbiotic Rhizobium nitrogen fixing bacteria that can take nitrogen from the air and convert it to a form usable by plants as a fertiliser.

Nitrogen is a critical element for plants since it is a core component of many plant structures and for plants internal and external metabolic processes.

Plants such as comfrey, peas, beans, alfalfa, clover and oats are regularly used to increase soil fertility.

Plants are nature's greatest fertiliser. When they die, they decompose and add organic matter to the soil. This organic matter is filled with nutrients that can be used by other plants. All parts of the plant its roots, stems and leaves contain nutrients which can be turned into the soil or chopped and dropped directly onto the bed as a mulch.

As plants decompose, they attract beneficial bacteria and earthworms. The soil is filled with microbial life that starts to break down these plants into available nutrients for plants to use when they need. Earthworms play a great role in aerating the soil and improving water retention.

Studies have shown that heavy metals, organic contaminants, antibiotics, and pesticides found in soil and water can be remediated using specific plants. Bioremediation processes use these plants to transfer, remove, destroy or stabilise contaminants. It’s a cost effective and environmentally friendly way to clean up soil.

Plants that have been used in this process are sunflowers, mustards, hemp and willow trees.

In our gardens we may not need to address heavy contaminants such as lead but rather improve our soil fertility so it can support the plants and food we want to grow.

For more information about plants that can help improve soil, visit the Permaculture Research Institute website.

Comfrey, pictured above, is a perennial that can thrive year after year. It’s believed to be excellent at bringing hard to reach nutrients closer to the surface through its deep reaching roots. As it decomposes these nutrients can then be used by other plants. •