Benefits of organic matter

Organic matter plays an important part in the management of soils. The main benefits are:

• living organisms in the soil play their part in the conversion of plant and animal debris to minerals and humus;
• Rhizobia and Azotobacter spp. fix gaseous nitrogen;
• plant roots, earthworms and other burrowing organisms improve the soil structure;
• many types of bacteria play an important role in the detoxification of harmful organic materials such as pesticides and herbicides;
• dead organic matter is food for soil organisms and increases microbial activity;
• dead but recognizable organic matter physically opens up the soil and improves aeration;
• fine, unrecognizable organic matter helps improve the water holding capacity of the soil;
• decomposing organic matter provides a source of dilute slow release fertilizer;
• humus coats soil particles with a black colloid and modifies their characteristics:
  • darker soils warm up faster in the spring;
  • organic matter improves water-holding capacity;
  • cation exchange capacity is increased, which can reduce the leaching of cations from the profile;
  • on sandy and silty soils the humus enables stable crumbs to be formed;
  • the surface charges on humus are capable of combining with the clay particles, thereby making heavy soils less sticky and more friable.