Tread carefully: life in the soil

Date posted: 23 December 2016

Often when visitors view our lucerne City Crop they're captured by the green foliage or purple flowers. But many don't stop and think about the world beneath the plants – the soil.

You might be surprised to discover that soil is one of nature’s most complex ecosystems, hosting a quarter of the world’s biodiversity. It's filled with a myriad creepy crawlies, bugs and slugs and microscopic marvels – making it a living wonderland.

But what does a soil ecosystem look like? The International Year of the Soil campaign (2015) states that a typical healthy soil, like under our lucerne plot, might contain:

• Vertebrate animals (those with a backbone/spinal column)
• Earthworms
• Thousands of species of invertebrates (those without a backbone/spinal column)
• Thousands of species of bacteria and actinomycetes
• Hundreds of species of fungi
• 50-100 species of insects
• 20-30 species of mites
• “Tens of species” of nematodes (or roundworms)

In fact, assessment of productive soils has found there may be as many as 100 million to 1 billion bacteria in one teaspoon of soil. This means, there are more organisms in a tablespoon of healthy soil than there are people on the planet (FAO 2015).

Soil organisms perform vital functions in the soil ecosystem, such as:

• Maintaining soil structure and nutrient cycling
• Decomposing organic matter
• Forming symbiotic relationships with plants (for example, lucerne works in symbiosis with Rhizobium bacteria to fix atmospheric nitrogen – this means that our lucerne crop is actually fertilising the soil with the important nutrient nitrogen as it grows!)
• Regulation of soil hydrological processes (i.e. how water moves through the soil)
• Gas exchange
• Soil detoxification and suppression of parasites, pests and diseases

Overall, soil organisms and the ecosystems they form are essential to ensure a functioning soil that can support plant growth. Since 95% of the world’s food is directly and indirectly produced on soils (FAO 2015), protecting the world’s soils is a must to ensure the future of sustainable and healthy food production.

Our Botanic Gardens horticulturists work hard to care and nurture the City Crop soil - visit the Crop during your next Garden visit or stay tuned for our next blog.

References

FAO (2015) International Year of the Soils