Digging is the key to assessing soil health, according to Lancashire-based consultant James Bretherton but a good nose can help, too.
At a Soil Association meeting at Upper Largo he told attendees that the smell of the soil was as good an indicator as any.
“When you turn over soil there should be that typical earthy smell that indicates bacteria at work.”
He said if there is no smell or, worse still, a sour smell, it suggests that things are not well.
He compared a healthy soil to a cow’s rumen, with bacterial action being key.
“It has been calculated that one teaspoon of soil can contain up to a billion different microscopic organisms of many different species, many of which we know nothing about,” Mr Bretherton added.
Anaerobic conditions caused by compaction made it difficult for these bacteria to survive, and factors such as livestock poaching, large machinery and over application of slurries could cause this sort of damage.
Compaction could be relieved by mechanical means such as soil slitting and subsoiling, but these types of operation should be carefully targeted and not simply used as a routine.
Soil might consist of 46% mineral, 23% water and 23% air, but it was the balancing 7% or thereby which was vital.
Organic matter might be a small proportion, but it was vitally important for providing soil structure as well as providing a medium for nutrient exchange.
It also hosted the all-important “rumen” bacteria.
“Without them we are doomed,” he said dramatically.
Worms were also hugely important and they could only survive in healthy soils.
“You should look for six to 10 worms per cubic foot of soil.
“The mighty worm helps with soil drainage, which leads to warmer soils.
“They move a remarkable amount of soil and their excrement is highly nutritious,” added Mr Bretherton.
For farmers to know their greatest resource they had to carry out detailed testing.
Where deficiencies were found, then suitable materials had to be added.