For the second time in as many months Tableland farmers have been warned that agricultural soils and pastures are severely depleted of essential minerals and humus.

Soil biologist Dr Christine Jones issued the blunt message to a gathering of 75 farmers and graziers at a meeting hosted by natural resource group Terrain at Walkamin last Thursday.

More to the point she said most parts of Australia are farming on subsoil with almost no trace of essential microbes to balance soil nutrients.

A totally attentive audience was told soil nutrients were so low in many commercial cropping and grazing areas that consumers would need to eat twice as much red meat and three times more fruit to gain the same nutrients of 50 years ago.

“Inorganic fertilisers are actually poisoning the soil,” Dr Jones said, and as a consequence, “there is no denying there are less and less nutrients in food which are at their lowest level ever.

“Fertile topsoil is the product of photosynthesis and microbial resynthesis which in effect is light farming.”

Dr Jones explained that 85 to 90 per cent of plant nutrient acquisition is microbial mediated.

“Although farmers can increase yield in some instances with chemical fertilisers, for example, of vegetables, they are low in nutrient.

“Copper, calcium, iron, magnesium and potassium levels have seriously declined by more than half and iron levels in meat are now much less,” Dr Jones said.

The field of agronomy did not escape unscathed, with Dr Jones scalding some agronomists for promoting high usage of inorganic nitrogen, a process which she says is unnecessary in sustainable farming methods.

“The atmosphere contains 78 per cent nitrogen, and there are 10 tonnes of atmosphere existing over one square metre of land, which equates to 78,000 tonnes of nitrogen over one hectare(2.47 acres),” explained Dr Jones.

“Why do we need chemical fertilisers such as urea which has less than 50 per cent plant recovery of nitrogen when there is so much available nitrogen that can be utilised by soil bacteria(diazotrophs) which fixes nitrogen but can’t function in the absence of green plants?”

Warmer, far north, red soils in particular need phosphorous but when applied as a fertiliser only 10 to 15 per cent is available.

“Phosphorous deficiencies in animals and humans can lead to serious diseases such as muscle wasting and other degenerative problems,” she said.

“Grasses and crops can fix their own nitrogen in the soil if there are the right fungi and bacteria present.

“We need to remember that these fungi are the highway and internet of soil.”

Meanwhile Bio Inputs specialist Chandra Iyer said in spite of the parlous state of soils in general, that bio fertiliser and bio pesticides are available to take the place of chemicals and insecticides and bio growth promoters can be utilised for larger scale farming.

He gave the example where bio-stimulant molasses or kemp is used in a broadacre application by spraying a molasses solution on wheat stubble for composting.

The Indian Government subsidises bio fertiliser because farmers are unable to afford nitrogen or phosphorous.