Nitrogen – microbial mineralization & fixation

Nitrogenous fertilizer production relies on non-renewable resources in a costly process that often makes them the most expensive input into conventionally managed Australian dairy pastures.

The transition towards sustainable farming practices naturally involves a move towards taking advantage of renewable nitrogen sources through the processes of ‘mineralization’ and ‘fixation’.

A steady-state nitrogen suppply - mineralization & fixation

For a sustainable dairy farmer mineralization of organic compost accounts for most of a pasture’s nitrogen needs however this is reinforced through the ‘fixation’ of free atmospheric nitrogen by microbial activity in healthy soil.In a mutualistic relationship the microbes exchange their ‘fixed’ nitrogen for carbohydrates supplied by the plant.

Soil health

Healthy well aerated soil rich in microbes, earthworms, dung beetles and other macrofauna provides an environmrent that boosts the growth of clover, sub-clover and pasture legumes that maximise atmospheric nitrogen fixation and mineralization of organic nitrogen.


In this video Terry Stokes speaks with Australian organic dairy farmer Liz Jordan about the transition to organic dairy farming, the use of organic fertilizer inputs, nitrogen fixation and the benefits she has experienced in cattle health, farm production and farm profits.