How have the Australian landscape and its soils changed?
Natural Sequence Farming (NSF) recognises that many European-style land use practices compact soils and reduce natural vegetation. This greatly increases the amount and velocity of surface water flows.
Streams that once meandered with pools and riffles have become straight channels that are dry for much of the year because they drain water quickly from the land. This causes severe loss of nutrients through erosion of surface soil and organic matter.
Prior to these practices, water rapidly infiltrated into the soil and was readily available to plants with percolated water having longer persistence and lower turbidity than surface runoff.
The slower flow of water in meandering streams coupled with increased percolation also provided opportunities for groundwater recharge - important for deep-rooted plants.
How can Natural Sequence Farming rehabilitate and create soils?
While many soils have lost their pre-European settlement profile, their functionality can be restored. NSF approaches can improve the soil structure and availability of organic matter resulting in increased plant production without increased water usage.
The important elements of NSF in improving soils are:
- Maintaining good vegetation cover
- Mulching organic matter to improve soil structure
- Maintaining a diversity of plants including deep-rooted species
- Diverting water into floodplains to increase its residence time in soils
- Structuring streams to reduce flow velocities
- Using structures in streams to provide productive flow form patterns in freshes
These NSF approaches result in increased microbial activity helping to provide essential nutrients in a readily available form. NSF approaches do what mineral fertilisers cannot do - produce a functional soil rather than just a hydroponic support medium.
A diversity of plants is encouraged by NSF succession approaches using grazing, slashing and mulching to produce a resilient system with essential elements. As surface soils are often prone to leaching, NSF advocates deep-rooted plants to stabilize them while accessing and recycling trace elements to support later successions of palatable grasses.
For soils and plants, the role of NSF structures in generating flow form patterns in streams can be as important as reducing the velocity of flows. Certain patterns can help produce new soils through the deposition of sands, clays and organic matter on the floodplain while protecting the lush vegetation already there.
