World Soil Day Q&A!
Each year, World Soil Day celebrates the importance of soil health and raises awareness for the sustainable management of our soil resources. The theme for World Soil Day 2020 is ‘Keep soil alive, protect soil biodiversity’.
Sampling the soil at Winona to assess the soil microbial biomass.
What is soil biodiversity and how can we manage soil resources to protect it? We asked soil scientist Katharine Brown a few questions on how to protect soil biodiversity and keep soil alive:
Q. What is soil biodiversity?
A. In the simplest terms, soil biodiversity is the variety of living organisms in the soil. The living soil may include bacteria and fungi as well as larger soil organisms such as earthworms and insects. It is estimated that greater than 25% of the living organisms on Earth live in the soil!
Q. Why is soil biodiversity important?
A. Soil organisms represent the soil ‘workforce’. They contribute to soil health, plant growth, water purification, carbon sequestration and human health. A range in workforce skills (soil biodiversity) will result in greater outputs (soil productivity).
Q. How do we protect soil biodiversity and keep soil alive?
A. Soil organisms have the same needs as we do. They need air, water, food and shelter to survive. Implementing land management practices that promote soil aeration, maximise water infiltration and retention, provide a food source for the soil organisms and preserve the soil structure, will protect soil biodiversity and keep the soil alive.
Smelling the soil at Rothesay. Healthy soil with a diversity of active organisms will smell earthy and sweet.
Q. What can land managers do to protect soil biodiversity?
A. There are a number of ways land managers can both protect and encourage soil biodiversity. Maximising groundcover and minimising soil disturbance are two effective methods.
Groundcover, whether it be green plants, stubble, mulch or leaf litter, protects the soil surface, promotes infiltration, stabilises the soil (think anchoring roots and root exudates binding soil aggregates), and contributes as a food source.
Minimising soil disturbance preserves the soil structure (shelter for soil organisms), reduces the rate of breakdown of organic material, and reduces the loss of soil biodiversity as a result of soil erosion.
Q. Does soil organic matter help soil biodiversity?
A. Increasing soil organic matter will definitely help soil biodiversity. Planting green manure crops or spreading mulch or compost are examples of how a land manager can increase soil organic matter. Managing the ratio of carbon to nitrogen in the soil to control the rate of organic matter breakdown and the release of nutrients is also important.
Ground cover after rain on Milgadara.
Q. How do plants contribute to soil biodiversity?
A. Plants contribute by transforming carbon dioxide and water from the air and soil into sugars (a food source for soil organisms) through photosynthesis. Some plants contribute to the soil (for example, nitrogen fixing legumes), others deplete the soil, particularly under agricultural land uses. Introducing plant diversity and rotation can help to both preserve soil nutrients and prevent pests and disease. In addition, planting trees, shrubs and grasses (along boundaries for example) will provide habitat and food sources for soil organisms.
Q. Does the use of chemicals have an effect on soil biodiversity?
A. Yes. A useful analogy is to consider the effect antibiotics have on our gut bacteria. It is common knowledge that antibiotics can eliminate both harmful and beneficial bacteria. Ultimately, the balance of the gut biome is disturbed. A similar imbalance will occur in the soil when chemicals are used to either eliminate or promote an element or organism. Minimising the use of chemicals will help to maintain the balance and diversity of soil organisms.
Learn more about soil biodiversity and World Soil Day from the UN Food and Agriculture Organisation.