As Monbiot once said - we need to stop treating the soil like dirt
Outside a house where I am on my wanderings, two young men are digging out an old redbrick wall which had been in danger of collapsing.
It had begun to reveal a gradually evolving beer-belly bulge, a swelling built up by pressure from a bank of soil, moisture-absorbing and moving by stealth with the gravity of a garden slope. The property dates from 1904.
The soil being dug out is beautiful; it is loamy and crumbly brown from what a long time ago was a river bank and is so rich in nutrients that trees and other growth have sprung up, reaching quickly for the skies.
And it is a tree that has brought the diggers, with spade and shovel rather than some mechanical aide, to bend their backs. A eucalyptus, that Australasian fire-bird, bane of foresters especially in southern Europe, had sent down its powerful roots like a tentacled dragon which knew no property boundaries and cracked into a drain on its inexorable journey.
The spade wielders, urbanites, recognised the richness of the clay they were piling up. Wonderful topsoil, we agreed, I thinking of an allotment that would welcome it to clothe bareness leavened by generous applications of manure.
All human life depends on the soil, the writer and environmentalist George Monbiot reminds us. A Sanskrit text of 1,500BC says: "Upon this handful of soil our survival depends. Husband it and it will grow our food, our fuel and our shelter and surround us with beauty. Abuse it and the soil will collapse and die, taking humanity with it."
This is a grim forecast.
Monbiot asks us to imagine a wonderful world with no threat of climate breakdown, or loss of fresh water, no obesity crisis, no terrorism or war; surely then we would be out of major danger? Not so. He is pessimistic.
We are finished, he says, if we don't stop destroying the soil beneath our feet which we treat, yes, like dirt.
Most media do not bother to consider it, he suggests, but 12 million hectares a year are lost through soil degradation.
There is an orgy of destruction going on, so intense that, according to the UN Food and Agricultural Organisation, there are just about 60 more years of crop growing left, an average of about 100 harvests. And to keep up with global food demand, the UN estimates that six million hectares (14.8 million acres) of new farmland will be needed every year.
Monbiot says that the techniques that are supposed to feed the world are now bringing the threat of starvation.
Intensive farming over the past century has increased the rate of soil erosion sixtyfold. Recent research has shown that soil on allotments where small crops are cultivated is in much better condition than on farms and is producing between four and 11 times more food per hectare.
I am often accused of sentimentality when criticising contemporary industrial agricultural practices, the compacting of the earth by mammoth machinery, levelling of ditches, unnecessary drainage and destruction of small field systems, indiscriminate use of pesticides-herbicides, the hammering down of insect, bird and mammal.
This surplus dug-out soil of the wall workers should find a new and life-enhancing purpose on an allotment, producing vegetables annually in however humble a fashion.