Papers & Presentations
We get what we deserve…
A visual impression of the “Salinity Problem”
A case presented by Chris Henggeler, Kachana Pastoral Company, March 2004
This is not a photo of tidal flats with saltpans and patches of mangrove thickets taken from an aircraft. We can however readily observe a common symptom of “salinity”: salt crystals lying on the surface.
Closer to the ground we view “salinity” at the micro-environment level. Salt or rather water-soluble minerals will tend to take a ride with the next drop of water that moves past. In this case ground-water rose to the surface and evaporated leaving behind a “salt problem“.
The other side of the coin: a high rainfall area. In this micro-environment (immediately adjacent to the “salt problem”) we notice algal growth… We had salt here too. In fact below the surface in both areas there is no difference. The difference is that in the “high-rainfall area” in ‘photo three’ most of the salt has been washed away and a monoculture of algae is coping with what is left. This tells us about a potential for biological “soil-building”.
There are a few simple messages in what we see:
- There is a source of unstable water-soluble minerals in the ground.
- In this case they are finding their way to the surface.
- In ‘photo two’ we observe a “salinity problem” and no visible life.
- In ‘photo three’ we have a “leaching of minerals” out of the area, but there is some life on the surface.
Questions we could be asking are:
- Are in this case “salinity” and “the leaching out of minerals” simply two different symptoms with a common root-cause: unstable water-soluble minerals making their way to the surface?
- Why do we have unstable water-soluble minerals in the first place?
- Is this so different to what we see happening at the macro-environment level?
- How could we work with nature to benefit from the situation?
- How could we work with nature to change the situation?
- Is there the potential to build biodiversity?
In this case the answer to question No. 2 can be found by stepping back and looking at the context: see ‘photo four’ (below).
What we were looking at is a porous “concrete” slab made of local dirt mixed with cement in a ratio of about 6:1. During the high-rainfall months ground water rises bringing water-soluble minerals to the surface. One side of the slab is exposed to high rainfall and much of the salt gets washed away and biological succession is visible in the growth of algae; on the inside of the tin structure the microclimate is much drier and there is less “flooding” so we find concentrations of water-soluble minerals building up.
“Photo five” shows an edge of a human-made lake in a broader landscape setting. This environment is situated in the tropics and receives about 700mm rainfall annually. Rain comes down intermittently mainly in the warmer part of the year over a time period that can range from a few weeks to a few months.
From two thousand feet above the ground we can readily see bare eroding areas. Devoid of ground cover, these areas supply loose particles from the surface and from gullies. Water-soluble minerals (that reach the surface through surface-evaporation much like what we saw in ‘photo two’) are washed into the lake with these particles. New and higher groundwater-levels around the edge of the lake speed up the process of ‘salting up’ the lake. As more sediment enters the lake, the volume of water-storage in relation annual surface-evaporation becomes smaller. This factor also contributes to rising salinity in the lake. In the short to medium term the picture is blurred by another process: The country covered with grass, shrubs and trees will supply organic material that also gets washed to the lake. Much of the debris left behind after wildfire gets flushed along too. As watercourses leading into the lake get choked up with these nutrients we tend to find an obvious increase in fertility, biomass and also in biodiversity around the lake’s edge. Good news? - Maybe… the key is Landscape Management.
Unless, such a situation is effectively managed, it is highly probable that in the long-term the current trend of ‘less groundcover’ where the water flows from, will continue. The consequence would be an increasing transfer of soluble minerals into the lake. If the aquatic life that is developing in the lake cannot deal with this gradual increase in salinity, in time, the lake will turn into a salt lake and it will kill the vegetation around it’s edge. A processes much like the one that changed many of Australia’s natural fresh-water lakes into salt lakes so many years ago?
It is of course a “natural process” inasmuch as natural principles and laws apply to what-ever “changes” have taken place. If human induced disturbance triggers such a process, it can then be argued that “what we get” is “natural”.
What sort of “change” must we humans induce at landscape levels so that “what we get” is “what we need”?
The good news is that we are not alone in our thinking!
Do you know about the Matetzi Project? http://managingwholes.com/zimbabwe.htm
We are also beginning to get these sorts of results in other countries: http://managingwholes.com/__land.htm
Conventional “control-referenced” and “reductionist-type” research does not become obsolete. It still remains important to maintain and improve industry and to gather data for information. However at landscape levels we require “goal referenced research” to provide the basis for sustainable productivity.