Carbon and Microbes:
The Invisible Workforce
Pasture cannot exist without organic carbon yet of all the minerals farmers talk about the most important is the most overlooked.
Cropping soils high in organic matter and microbial life operate at temperatures 2 degrees higher than soils without. Therefore, biologically active soils have a greater productivity leading to improved pasture performance by prolonging the growing season.
In contrast the burning of crop residues, rank pasture, or scrub does not allow soil life to operate this level. Despite the depositing of highly mineralised ash, the substantial loss of carbon coupled with an exposed soil surface reduces the ability of the soil to regenerate itself.
Only a soil surface covered with stable litter and humus layers maintain a high biological activity that reduces impacts of droughts, floods, cold, and erosion. It does this by reducing evaporation, protecting the soil surface from wind, rain, and animals, and providing storage for organic compounds necessary for plant growth.
How does a biologically active soil contribute to improved mineral composition of pasture? This question is currently challenging attitudes in soil science. Soil chemistry and physics dominate thinking in this discipline through the traditional soil test.
Yet questions are being asked whether soil pH determines mineral availability and uptake by plants or the activity of soil biology. As ewes and lambs choose a higher nutritional plane than a paddock offers, do microbes in the soil operate the same way thereby releasing minerals at levels that differ from that found in the soil regardless of pH?
Could it be that soil pH is a symptom, not a cause of nutrient interaction in the soil? If so, and micro-organism species determine soil activity and nutrient cycling, should this challenge the way farming families plan their livestock grazing.
As families begin to realise the importance of an invisible soil borne workforce, grazing planning will shift from just feeding animals that are sold for income to include the feeding of micro-organisms in the soils of paddocks their animals graze. This means leaving soils covered when animals leave a paddock.
Carbon in the soil is like money in the bank, it can’t be withdrawn forever but if carefully managed can certainly be cashed in from time to time when market conditions are right to turn biological capital into financial capital. The fact that grasslands around the world have flourished with nothing more than grazing animals and soil biology signals this new way of planned grazing is also cheaper.
John King from Succession coaches farming families to make decisions that are profitable, regenerative, and bring enjoyment to land stewardship. Contact him at succession@clear.net.nz or 025 6737 885 or AH (03) 547 6347.