Emissions back into the soil

A RADICAL approach to farming using tractor exhaust emissions requires a radical exhaust system at sowing, reports MARK SAUNDERS

David Krieg's tractor exhaust is one of the longest you are likely to see.

It starts near the cabin like most others but runs down the back of the tractor, on to the air seeder and finishes at the seeder's tines.

It's part of David's new approach to farming, which involves pumping exhaust gas into the soil while grain is sown on his Weethalle, NSW, property Brigadoon.

The lengthy exhaust also includes a huge cooling system mounted on the air seeder.

The twin-fan intercooler is used to reduce the temperature of the exhaust gas from the tractor as it is pumped into the ground.

In fact, the tractor exhaust gas completely replaced the conventional fertilising program for the 3000ha of wheat and barley David sowed earlier this year.

Apart from several trace elements including zinc, manganese and phosphorous applied as a seed dressing at sowing, the exhaust fumes have been the only "extra" plant nutrition available to the crops, along with what was already in the soil.

With harvest now under way at David's property, it appears the gas treatment has initially been a success.

"The barley we started harvesting two weeks ago week yielded about three tonnes to the hectare and the wheat should be up to four tonnes a hectare," David said.

He appreciates cutting conventional fertiliser from his cropping program is a massive change on the farm but is confident the exhaust gas will do the job in the future.

"Changing to putting the exhaust emissions in the ground is somewhat of a 360 (degree turn) from convention, but we are still monitoring the nutrition in the ground with soil testing," David said.

"If it looks like we may be lacking in something we will use foliar applications if needed.

"But for the time being it looks like the exhaust fumes have done the job."

Putting the exhaust fumes into the soil may sound like a relatively simple exercise, but it's actually quite complex.

For a start, the emissions are close to 400C when they leave the engine - hence the king-sized cooling package mounted on the seeder.

The conventional exhaust stack near the tractor cabin is where the exhaust gas starts its journey to the seeder, which is an 18m Vaderstad tined machine.

The exhaust has a cap on top that can be opened and closed. When the cap is closed the exhaust gas travels down a large pipe over the seeder's drawbar, through the intercooler to the rear of the air seeder and then down the same tubes as the seed.

David said when it exited the seeding tubes, the exhaust gas was close to 32C.

The large tube which carries the engine emissions from the tractor to the seeder has a flexible joint located over the seeder drawbar to allow for movement between the tractor and air seeder.

David said the delivery system was designed, constructed and fitted by Carbon United, at Mildura.

"It's an exceptionally well-made system which fits on to the tractor and seeder like a glove," David said.

"The seeder still folds up the same way so it does not interfere with its normal function in any way."

Sensors on the system allow the tractor driver to monitor the exhaust gas temperature in the cabin.

David said because the air seeder was not carrying any fertiliser, it was lighter and meant the tractor used less fuel.

"We were able to come way back on the tractor engine revs at sowing so it was much more fuel efficient," he said.

"And our farm manager, Andrew, is over the moon as he does not have to handle fertiliser any more."

The Vaderstad seeder is hauled by a tracked John Deere 9400T tractor.

The seeder is set up with 305mm row spacings. The sowing depth for cereals is 25-30mm.

David said the Vaderstad produced an excellent crop germination but he also attributed "exceptional" early crop root development to the addition of exhaust gas to the soil.

"The barley germinated five days after sowing and I have not seen that here in 30 years of farming," he said.

David initially heard of the emissions farming system through Carbon United and was soon in touch with Canadian Gary Lewis, who has been accredited with pioneering the system.

Gary spoke at a recent field day at Brigadoon and said there was a growing trend of emissions farming.

"It's being embraced in many countries around the world, including Australia," Gary said.

"I know it's a radical change for many farmers but I have been using it successfully for a decade now."

Gary said the emissions farming system is based on the theory the carbon monoxide from the exhaust gas emissions stimulates micro-organisms in the soil.

"The resultant microbial activity generates carbonic acid and this interaction helps 'release' trace elements from the soil, making them available to the plant."