'Conventional plough could contribute to famine'

Photo: Cross Slot no tillage drill

A New Zealand agricultural scientist slash machinery manufacturer claims conventional ploughing could contribute to famine because it causes high rates of carbon loss from soil.


Dr John Baker, has a MAgrSc in soil science and a PH.D in agricultural engineering, which these days are mainly deployed in the manufacture and sales of his Cross Slot no-tillage seed drills. His 'famine' claim is stretching it, and he obviously has a vested interest in this, however, he makes a valid point about carbon loss.


He says carbon is lost to the atmosphere through conventional ploughing and that studies show 15-20% of CO2 in the atmosphere comes from annual ploughing.


Vital ingredient
Carbon is a vital ingredient of soil, Baker notes. Plants that we eat all contain carbon. When they die they decompose and earthworms and other microbes take the products of decomposition, which are rich in carbon, into the soil and keep them there. Fair enough.


“When the soil is ploughed it releases much of the carbon back into the atmosphere. The long term result is a reduction in soil organic matter, which in turn leads to soil erosion, dust storms and ultimately famine,” Dr Baker says.


“Ploughing takes away the food sources of microbes that hold the soil together. Organic matter also stores water and the loss of both decreases the crop yields.”


Key-hole surgery
After 30 years of research at Massey University, Dr Baker researched and developed Cross Slot no-tillage drills which penetrate through crop residue on top of the ground and simultaneously sow seed and fertiliser in adjacent bands.


The no tillage process causes minimal or low disturbance to the soil, traps the humidity, preserves the micro-organisms and soil life and largely prevents carbon from escaping into the atmosphere. Further, by leaving the stubble and straw from the previous crop to decompose on the surface of the ground, it helps sequester new carbon into the soil. 


Food Prize
This year Dr Baker was nominated for the World Food Prize, which was announced last month at the State Department in Washington. Someone is taking his no tillage message seriously.


He points out it’s incredibly important for the soil to gain and trap carbon “if we’re to feed the 50% extra population in the world by the year 2050.”


“Only four percent of the world’s surface has arable soil and we have to learn to farm it sustainably which we simply haven’t been doing. That means no-tillage must replace ploughing as the mainstream food production technique.”


Fuel costs: a net gain
Dr Baker also claims no-tillage saves up to 80% of a farmer’s fuel costs in establishing crops and pastures. Typically no tillage drills are harder to pull through the ground and therefore require a more powerful (and less fuel efficient) tractor. However, no tillage requires fewer passes by the tractor; Baker says farmers typically use 50 to 90 liters of diesel per hectare during the multiple times required to establish a crop. By comparison no-tillage uses “10-20 liters per hectare”.


Dr Baker says that New Zealand farmers sow about one million hectares of new seeds each year. Recent Massey University research suggests that if low-disturbance no-tillage was used universally to sow these seeds it would result in about 1.5 million tonnes less CO2 discharged into the atmosphere annually.