Organic matter is the main driver in soil health. Carbon makes up about half of the organic matter component in soils. For every 1 per cent increase in organic matter, or 0.58 per cent organic carbon, at a depth of 15 cm can lead to an increase in water holding capacity of 3000 – 185,000 L/ha. The increase in the capacity depends on the soil type and climate.  

Other than the improving the water storage in the soil, increasing soil carbon and organic matter has both physical and biological benefits. The physical benefits include: 

  • Resilience against compaction 
  • General soil stability 
  • Creates spaces for water and air infiltration 
  • Prevents evaporation losses and temperature fluctuations. 

The biological benefits of organic matter include: 

  • Increasing nutrient holding capacity 
  • More effective nutrient cycling 
  • Buffering of soil pH 
  • Habitat for soil life. 

A way to tell if the soil structure is poor is the presence tight clods and crusting on the surface. Fallow periods, tillage, and erosion are the main ways organic matter is lost. Climatic conditions such as very hot, cold, or dry weather can affect soil carbon quite rapidly. Keep an eye on your regular soil test results to make sure that you are maintaining or increasing soil carbon. 

To learn more about your soils, visit the Hort360 Resources page:  

The Farm Water Futures project is funded by the Queensland Government Natural Resource Investment Program (NRIP).