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Water
Water
(dedicated to Prof Tony Allen)
Water holding
Water holding
As Climate Change kicks in (Links), we become increasingly aware that many of the related events involve water - droughts and flooding in particular. Walter Jehne explains all.
Water drives over 95% of global heat dynamics . Carbon dioxide 4%. Soils hold water like a sponge, and this property may save the planet.
Temperatures in deserts - often bought about by bad farming (eg Romans wrecking Northern Africa creating Sahara) - can be 60C degrees whereas forests rarely above 20C - except when on fire. Somebody could calculate the reduction on global warming that continual ground cover would produce.
Possible research p[roject!
Try measuring ground temperatures under different cropping conditions. What are the implcations for global warming?
Canberra Australia: Now 7C cooler compared to nearby concrete jungle due tree planting.
We hear this a lot - how Water vapour increases greenhouse effect
But if you keep the soil cool you reduce the re-radiation, cause of much more heat in atmosphere than CO2.
Holding
Holding
Rough calculation: A rise of 1% organic matter may enable soils to hold over 3,000 gallons water available for plants per acre (top 1ft) - on top of 70, 000 it may already be holding. Details
Rough idea what that looks like. Below is football pitch of about a hectare, one half being about an acre. In terms of water, a bucket can hold 3 gals, water butt 30 gals, outdoor pool 300 gals and 3000 gal storage.
Compaction
Compaction
Compaction encourages runoff and kills much below it. Increasingly degraded soils, worldwide 750m tonnes being lost a year
Soil cannot be replaced in our lifetimes.
In US predominantly drought, whereas..
Comaction is becoming an increasing concer as the size of tractors and trailers get bigger.
Tread carefully
The similarity in mass and contact area between modern farm vehicles and sauropods: What was the mechanical impact of these prehistoric animals on land productivity? Farm vehicles have grown over the past few decades, to the point where they may be compacting the subsurface soil where roots of crops extend.
Today, that average weight (of a combine harvester) has grown to over 35,000 kg. To avoid crushing the soil beneath this bulk, tires have got larger, and they're operated at lower pressures, allowing the tyre to spread over a larger area to limit the compaction of the surface soil. The stresses (that go deeper down) largely depend on the mass per wheel”
Erosion
Erosion
Air Across world much erosopn to air. 4 bil tonnes of clay dust going into air contributing to Greenhouse effect - the humid haze.
About 2m tonnes lost in East (arable) into North Sea. Grade 1&2 - our best soil from arable land. 1 m tonnes (brown) lost in West (pasture) into Irish Sea. Grade 3-5 - poorest soil off moors
How much life would each of these tonnes represent? Most people are concerned with the silt that runs off, but that silt would have been soil with all sorts of life in its pores.
UK Soil erosion following rain. Photo take by satellite shortly after heavy rain.....of which we are getting more. The rivers are running faster and eroding more soil. Save our Arable Soils
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