Quality of production is based on the interaction between soil parent material and humus build up.

A common misunderstanding is organic matter being confused with humus. Indeed one leads the other but they are not the same. In simple terms humus can be described as the end product of organic matter but the point is that it is not an automatic process and appropriate conditions, inputs and management is required. Humus distinguishes quality of top soil and differentiates top soil from sub soil. It is incumbent on farming practice to enable and maintain the conditions for humification in order to retain the long term productive capacity of soils.

So what is humus?
Humus is the result of macro and micro-organisms digesting organic matter into smaller particles. These smaller particles are then recombined into a wide variety of large molecules by the activity of another set of micro-organisms. These complex, diverse and stable molecules form what we know as humus. It is a two step process in which the digestion of (fresh) organic matter by a community of micro-organisms provides plant nutrients including CO2, Anions like N, P and S, Cations like Ca, K, Mg, Na, and Trace elements. Another community of micro-organisms will re-synthesise (humification) the “left over’s” into large 3D molecules called humus. Both processes of mineralisation and humification are required to feed the pasture and/or crop and to sustain soil/plant health and quality.

Without the processes described above organic matter remains just that, organic matter. Unless there is an active mineralisation and humification process organic matter is simply unrealised potential.

What does humus do?
Humus provides stability through complexity in soil, and as a spin off, in the plant. Humus buffers levels of extremes, e.g. extreme weather conditions, harsh or large inputs or actions. Humus secures the proper distribution of water, air (oxygen and CO2), warmth, food (plant roots and soil micro-organisms), buffers pH against extremes and sequests carbon captured from plant material, water and atmosphere (micro-organisms).
 
Humus is also where metabolic substances are created and stored such as enzymes, secondary metabolites, vitamins and natural growth hormones.

How do we balance digestion of organic matter and humus build up?
We need to provide water, air, food via plant roots and soil (micro) organisms, appropriate pH and balance the cation minerals. Soil structure maintenance is required and contributing to this are diverse pasture species providing a variety of plant root systems. Functionally available calcium and phosphate is required by the soil/plant energy system which can provided by an integrated biological input, mineral and management plan.

The role of soil biology in the maintenance and enhancement of humus is now recognised by a rapidly growing number of farmers. These farmers adopt a holistic approach to their farm management whereby they correctly observe and connect nature’s organic cycles with appropriate mineral and physical management.

Building humus represents an investment in natural capital, the soil and is applicable to all farmers.

Steven Haswell, Managing Director, BioAg Ltd
Acknowledgement to Frank van Steensel M.Ag.Sc

 Quality__Humus_Editorial.pdf

If humus levels go down so will the diversity and amount of micro-organisms that provide plant nutrients and feed the humification process. This reduction in plant food supply will result in a downward spiral first affecting plant health, then animal health and produce quality. Generally this downward spiral is masked by increasing amounts of fertiliser inputs to secure production levels and agri-chemicals to treat symptoms.