Soil health
Soil health means less inputs, same yield
Australian Canegrower Magazine (25 July 2005)
Like many farmers across Australia trying to maximise productivity sustainability, Herbert River sugarcane grower Peter Carr has an almost intense focus on soil health.
He says that our basic problem is carbon: too much in the atmosphere, not enough in the soil.
He also talks of mycorrhizal fungi and their crucial symbiotic relationship with plants and how too much phosphorous in soil closes them down.
He is convinced that modern farming practices are destroying our soil, rendering it structureless and bare, stripping it of the organisms which give it water and oxygen holding capacity and enable the transfer of essential nutrients from earth to plant.
Mr Carr’s concern is especially relevant in the sugarcane industry, where a yield plateau thought to be caused by monoculture, excessive tillage and the relentless use of fertiliser and other chemicals has been the focus of a massive research effort by the Sugar Yield Decline Joint Venture (SYDJV).
He joins a growing numbers of farmers in other agricultural sectors, including wheat, vegetable, beef and cotton growers in Queensland and New South Wales and Victorian viticulturists, who are advocates of controversial United States soil biologist Elaine Ingham.
He considers a 2000 seminar in Ayr conducted by Ms Ingham to be a turning point in his farming practices.
After the seminar he bought a booklet written by her on soil biology. It provides an introduction to the living component of the soil and how that component contributes towards agricultural productivity and air and water quality.
"It’s something all farmers should read before they get on a tractor," Mr Carr said.
The book by Elaine Ingham motivated him to progress his interest in the findings of the SYDJV. Briefly, the research confirms that the starting point for developing a robust cane farming system is a healthy cane plant.
Traditional plough-out/replant cane growing systems encourage the pests of cane roots, such as pachymetra and nematodes, while trash burning and aggressive tillage suppress beneficial soil organisms.
In addition, says the SYDJV, much of the field is compacted by heavy machinery during harvesting, further restricting root development.
To summarise, yield decline studies have shown that healthy root systems and high cane yields are obtained from adopting well-managed soybean fallow breaks, minimum tillage planting and controlled traffic, where tyres are kept away from cane rows.
Beneficial soil organisms that help suppress root-feeding pests and diseases increase with no tillage and retention of crop residues.
Large, healthy root systems are better able to withstand canegrub feeding and drought. Uncompacted soils are better aerated and drain better during wet conditions.
Cane is more resilient to stress when it has a large, healthy root system, and is likely to yield better under hard conditions.
Gathering its most useful results into a workable package, the SYDJV advocates integrating soybean break crops, minimum tillage planting, trash blanketing, controlled traffic and biological control of pests and diseases into a farming system which is profitable and sustainable.
Mr Carr has followed closely the work of the SYDJV and, through the Internet, similar developments worldwide.
"I could see that the rest of the agricultural world was headed towards a minimum tillage/controlled traffic system. The cotton industry took 10 years to sort it out. I could see that we had a few things to learn."
Seven years ago Peter and his brother Rex began to implement Sugar Research and Development Corporation recommendations reflected in later findings by the SYDJV.
They commissioned Peter’s son, Ian, a multi-skilled tradesman who works at Victoria Mill, to build a whole-stalk, dual-row planter and now have 130 ha under a 1.8 m dual-row minimum tillage/controlled traffic system.
As well as the planter, son Ian converted a finger rake to move soil into a mound which has the right profile for the harvester.
This year, for the first time, the Carrs did not use a gram of fertiliser on their plant cane.
"We’ve had soybeans in," Peter said. "And we have found from previous years that the amount of nitrogen you get from a soy crop, you just don’t need to put nitrogen in your plant cane, and I think the effect carries over for a couple of ratoons."
However Peter stressed that soil nutrient analysis, biological analysis and leaf analysis were crucial to the success of this type of farming.
Seven years of carefully controlled fertiliser use and reduced tillage have paid handsome dividends for the Carrs.
"An analysis of our production figures by our accountant says that we are viable at $27 a tonne of cane," Peter said.
"We are producing the same yields with less inputs. We are down to 103 kilograms of nitrogen per hectare. Seven years ago we were using 150 kilos a hectare. I think we could reduce even further, down to 100," Peter said.
Harvesting this fortnight, 500 tonnes came in at 14 CCS with mill average 11.9, at 90 tonnes per hectare.
A recent productivity board analysis recommended that the Carrs stop using phosphorous for two crop cycles on one of their paddocks. That means no phosphorous for 10 years.
"And I agree with them entirely," Peter said.
Then there are the personal spinoffs. Because there is not as much work in a reduced tillage operation with 1.8 m rows, the pressure of the annual farming routine has eased.
"The moment you go from 1.5 m to 1.8 m you get a kilometre less running in each hectare. So there is an enormous fuel saving," explains Peter.
"You are more relaxed. There’s less labour involved. You’re letting the soil biology do some of the work for you. It means that one ‘switched on’ young farmer can handle a lot of cane.
"My brother Rex handles our annual production of 12 000 tonnes of cane and still gets his fishing in. He does most of the tractor work and finds that it’s just so much less time when he doesn’t have to rip up that interrow.
"Now that we’ve given up putting a tractor track on the one metre of soil we plant the cane in it’s chalk and cheese. The soil is so much more friable.
"Modern farming methods are destroying soil health. We are using too much phosphorous and nitrogen. It makes the soil biology lazy. There’s plenty of nitrogen being produced in the soil by bacteria."
Savings from the minimum tillage/controlled traffic system extend further than fuel. Now, crop nutrition, including lime and mill mud, is concentrated squarely on the planting zone, rather than the whole paddock.
"We were putting fertiliser and lime where it wasn’t needed. We used to broadcast lime over the whole paddock.
"I asked the contractor whether he could blank off the interrow and put the lot in the cane row. It halved our liming costs. The soil is too compacted in the interrow for the roots to reach it anyway."
The results he has achieved have convinced Mr Carr that if growers cultivated the ground less and paid more attention to soil health they could farm more productively and economically.
He says that too many farmers stick to the old idea that they should aim for big tonnes of cane per hectare.
"But it’s dollars per hectare you’ve got to look at, the net result after taking out the fertiliser costs, fuel for cultivation and even the harvesting of extra tonnes.
"With a lot of nitrogen you can grow a lot of tonnes, but every extra tonne is about $6.50 to the harvester.
"I’ve done my sums. All of my comparisons show that we’re using far less fuel with far less time and energy and, with the soybean fallow, far less fertiliser – and we’re still growing the same amount of cane."
