Soil Structure in the Wet Tropics

In this video: Learn about what soil structure is, why it is so important and what to do to improve it.

A healthy soil has good structure which means friable and open and it allows air water and roots to move freely through and into the soil.

Benefits of good soil structure

  1. It's well aerated so plenty of air can get in and flow through the pores because its well aerated.
  2. Water can infiltrate your soil really readily instead of running off and taking sediment with it down the catchment-  but it also drains better because there's air pockets throughout that soil and not stay waterlogged as long.
  3. It provides an ideal environment for plant roots. Plant roots thrive in a well aerated well-drained situation and that's what good soil structure gives your plant roots - the perfect conditions for plant growth.
  4. It provides ideal conditions for the beneficial microbes in your soil to really thrive, which helps with nutrient cycling, fixing more nitrogen from the air and controlling soil-borne pests and diseases.

How to assess soil structure

  1. Do a hand test - get a clump of soil and gently crush it with your hands. It should break up into finer aggregates or smaller clumps. You don't want it to stay as a solid clump that you just can't move. Clods are a sign of bad soil structure. The other thing you don't want is powder.
  2. Use a penetrometer - this can tell you how dense the soil is.
  3. Test your aggregates to see how strong and stable they are by carefully placing it into a dish of water. It will either fall apart and collapse, go into suspension and make your water milky or, and this is what you want, it will just stay there and not collapse or move.

So what can you do to turn your Romano cheese into cottage cheese. One of the terms we use for poor soil structure is compaction and it's a big problem.

What to do about poor soil structure

  1. Control where your traffic goes - so if you're using tractors and machinery and your farming system, controlling the wheel tracks is critical for reducing compaction.
  2. Use deep-rooted fellow crops that actually can move through the soil and break compaction layers
  3. Reduce your tillage. Intensive tillage knocks around your soil structure and pulverises it and in the long run you end up with a pulverized talcum powder structure.

Poor soil structure and compaction is one of the biggest soil health issues in the Wet Tropics but there are things you can do to improve it.

If you want to learn more contact your extension agronomist or local WTSIP Extension Officer.