Horticulture must wean off tillage, says leading scientist
May 31, 2012
© Fresh Fruit Portal
New Zealand scientist Dr John Baker has been nominated as a candidate for the World Food Prize this year, which is due to be announced on Jun. 12. His invention, the cross-slot seed drill, helps retain soil health and has mostly been applied to cereal crops such as rice, wheat, maize and barley. He tells www.freshfruitportal.com about the destructive nature of tilling and how horticulture needs to catch up with other agricultural fields, building a more sustainable industry at the core level of microbes and foodstuffs.
The idea of horse and plough farming stirs up images of mankind at its roots; a traditional and healthy nostalgia in a world of large scale agriculture, tractors, research labs, high pressure irrigation and gigantic refrigerators.
No great economic revolution has ever come without a reliable and affordable food supply; a concerning fact considering the world’s population will hit eight billion by 2030, and Food and Agriculture Organization (FAO) statistics show there are still 925 million undernourished people around the globe.
Without the profound development of agricultural technology, the number of hungry people on this earth would be significantly higher still.
For Baker, the Malthusian population versus land equation has very serious implications for mankind, which means the available soil for cultivation needs to be treated and utilized carefully.
“In order to feed the increasing population in the world, the opportunities for creating new agricultural or horticultural land are just about completely expended.
“I guess some would argue that they can cut down some more of the Amazon Rainforest, but the reality is that only 4% of the world’s surface can grow crops.
“We have to learn to grow our food more sustainably, and that means to be able to use the same piece of soil repetitively without destroying the soil health, or having it disappear through a lack of water or wind erosion, and that essentially means stopping tilling the soil.”
Today, horses may have been replaced with tractors, but it is the way we plant seeds that needs to change. When farmers till their fields they oxidize the soil, breaking up the carbon that is stored within it and killing a lot of microorganisms.
“If you oxidize the carbon in the soil, you’ve just destroyed the foodstuff of the microbes, you’ve killed macrofauna like worms physically, and the food source becomes just a physical medium instead of a biological medium for plants to grow in.
“That greatly reduces the yield potential, but more importantly it exposes the soil to soil erosion from wind and water, and eventually that soil washes away and blows away, and in parts of the world we’re left with bedrock, and it takes 1000 years to create an inch of soil.
“All we’re doing is eating ourselves out of house and home; add to that that we build all our cities and buildings on the best soil anyway, because that’s where the civilizations start up, on the edge of rivers and harbors, which is usually where all the best soil is.”
It is difficult to change these habits, but Baker believes the industry will be convinced when it sees how profitable an alternative seeding method that preserves organic matter can be.
“How do you reverse this process? One, by not physically disturbing the soil, not ploughing it, and two by leaving the residues from each successive crop, the bit that we don’t use, and in agriculture we mostly use just the harvested seeds, leaving the rest to decompose on the surface of the soil.
“Of course that’s what the microbes want, and they are the mechanism to take the carbon back into the soil, what’s called sequestration, and giving it back to the crop.
“Man is very bad at changing his habits if it costs him money, but this actually doesn’t. It makes him money. The soil becomes more productive, so it’s a win-win for mankind.”
He says people often underestimate the importance of soil microbes and how many there are in the soil.
“In a teaspoon full of soil there are something like six billion microbes in healthy soil, and if you beat that up with a plough and other tillage equipment, you beat that figure down substantially and therefore you reduce the potential of the soil to support plant life, which is what we eat.”
He adds it is sad that many so-called ‘organic’ farmers also till their fields.
“That’s the most inorganic thing you can possibly do to the soil.”
The next step
Baker’s input to solving this problem has been a seeding drill that preserves carbon in the soil, which has been applied across millions of hectares in 17 countries.
His focus to date has been on cereal crops as they account for the staple diet of the world’s population, but now this has been achieved his next great task is to apply the same technology to horticulture.
He says even if the technology doesn’t come from his company, its advancement is inevitable.
“The next big development over the next 30 to 40 years will be horticultural machinery to do no tillage,” he says.
“The message for me is that agriculture is way ahead of horticulture in not tilling the soil. South America – particularly Argentina and Brazil, but also Chile, Uruguay and Paraguay – is leading he world in terms of adoption of no tillage practices for agriculture.
“Horticulture is going to have to make the same move, because it actually uses the soil more intensively than agriculture, but the development of machinery for horticulture to do this has lagged behind.”
“In terms of soil health and how the machine works, it’s all applicable to horticulture, and would be interesting for vegetable growers who think they’d like to get more out of the ground.”
He says the change would present a serious conundrum for some large companies such as tractor businesses, but others like large seed selectors would benefit.
“We have by far, and this is acknowledged by the USDA and FAO, the best soil engaging tools for the business end of actually sowing the seed in the ground.
“We need to, or someone else needs to, marry that to some of the very sophisticated seed selection mechanisms that already exist in the horticultural field, but that hasn’t happened yet.”
Baker points to one recent customer in Australia who is using the company’s technology to plant lucerne crops in between citrus rows, in a bid to build plant matter and restore soil nutrition.
“They previously poured loads of chemicals into the ground to keep away pests and all the rest of it, and the end result is that the ground is almost barren between the rows, and the citrus itself doesn’t add a lot of organic matter because it’s an evergreen and doesn’t drop a lot of leaves; the ground has had very little carbon and organic matter added to it for a long period of time.
“What he’s saying is that if he can grow a decent crop of lucerne, which would probably grow in the order of 10,000kg (22,000lbs) of dry matter per year and regularly mow that, the mower throws it to the side under the trees, he’s going to start rebuilding that organic matter, and that’s going to be good for the trees and add nitrogen to the soil too.”
He says another argument for restoring plant matter is that it stores water and reduces the need for large dam projects.
“As those soils get less able to support crops, the first thing mankind says is we need water, so they dam up the rivers and now we’ve got irrigation, and so we’re bringing the last little drop we can out of available water to feed them.
“But in reality one kilogram (2.2lbs) of humus or mulch has the same amount of water as nine kilograms (19.8lbs) of clay.
“As societies we have focused on the wrong things; we’ve focused on storing water by damming rivers, when we could have prevented much of the loss of that water by recycling the carbon in the form of humus into the soil.”