New concerns arise with new uses planned.
By Ralph Pearce
The term ‘residue management’ has arguably taken on new meaning in recent years. Research at Iowa State University in 2006 was trying to develop a new dual-purpose combine that takes the corn out of the field on one side and collects the stover on the other, in the hopes of feeding the fledgling cellulose ethanol industry. In a more domestic venture, Mark Hayhoe of K2 Milling of Tottenham, Ontario, achieved a measure of success by supplementing coal at the Nanticoke Generating Station on the shores of Lake Erie with loads of wheat shorts and wheat straw. His batch tests showed a significant reduction in noxious emissions as a result, enough to encourage continued efforts. He predicts that within 12 to 18 months, he could find enough residue, farm-based or otherwise, to completely replace coal at Nanticoke. But of some concern was his statement that in time, there would be nothing wasted from the fields.
The idea of eliminating waste is usually a positive. However, there could be a point where removing too much residue from growers’ fields becomes a problem. Anne Verhallen and Adam Hayes, both with the Ontario Ministry of Agriculture, Food and Rural Affairs, express their concerns on the issue, and have been monitoring the soil organic matter/residue management debate for a number of years. At the Growing the Margins Conference held in London in May 2007, the two were part of a group presentation that sought to answer the question of how much residue can be taken off yet still ensure soil organic matter is not mined to any detriment.
Verhallen concedes her concern for mining soil organic matter dates back to work by Dr. Fred Magdoff of the University of Vermont on silage corn. The value of that research has been brought home in recent years by the potential impacts of cellulosic ethanol, as well as what will be done with the tonnes of dry distillers grain (DDG) that are left behind by the growing number of conventional ethanol plants.
“People have concerns as well if they have a huge acreage of grain corn going into ethanol, the level of soil disturbance for planting corn is a lot higher than with wheat and soybeans, so there are concerns about more tillage and the potential for more soil erosion,” says Hayes, the field crops soil management specialist for OMAFRA. “We also get asked the question every year: ‘Should I be selling my wheat straw to make a bit more money or should I be hanging on to it and making sure it stays and gets worked back into the soil.”
Verhallen, the horticultural soil management specialist for OMAFRA, notes that in low wheat years there have been questions by some who require livestock bedding, as to whether they should be baling their corn stalks. That is a different situation: that if they need bedding, it usually means they have manure to return to the fields.
As for the DDG situation, a display at the 2007 Outdoor Farm Show on a project to study organic matter building included the byproduct as a potential source of compost to build organic matter, although the idea is probably more of a short-term practice. “When ethanol plants are in their start-up mode, they may not have the requisite heat or blend, so they have some off product, so that’s where the soil application comes in at this point,” says Verhallen. “Our other thought was with the huge increase in ethanol plants in the US: at some point, you start running out of things to feed the DDGs to.”
Challenges are economic – and real
Part of the problem of convincing growers to replenish organic matter is the opportunity for pay back should these markets for residue develop, be it to supplement coal or build cellulose ethanol plants. If those markets are to grow, then growers need to consider cover crops to aid in sustainability. “Any time you add a living cover crop in there, you’ve added another level of risk and our growers are not traditionally used to including a cover crop,” says Verhallen She acknowledges the work of researchers like Dr. Dwayne Beck who advocates blending different legumes and grasses to complement rotations. “However, if you get the recipe too complicated or make it difficult to source seed, it makes it much less attractive, and if they’re going to get frustrated, they’re not going to do it. Soil organic matter is that thing you have influence over 10 to 20 years of your lifetime farming, but the challenge is, getting the bills paid every year.”
Chad Anderson believes there are plenty of alternatives to help build organic matter levels; what may be missing is a more open mind when considering them. Like Verhallen and Hayes, Anderson recognizes the attraction of additional income streams. He knows continuous soybeans and shorter rotations have degraded soil organic matter levels during the course of two or three generations. “That’s not to say we can’t harvest cellulose and do a better job of managing and returning organic matter back to the soils from alternate uses, whether it’s manures or bio-solids,” says Anderson, a certified crop advisor from Brigden, Ontario. He questions the exporting of municipal sewage sludge to Michigan, creating pollution and degrading highways, instead of using it in fields in Ontario. “And then they’re dumping perfectly good fertilizer into a hole in the ground.”
The key for Anderson is to manage the drawbacks of residue removal. Discussing the virtues of dual-purpose combines, he agrees there is a purpose and a potential pay back. However, he also sees increasing traffic on the land. “If we’re going to compact the soil to take off the organic matter which buffers the compaction we have, then the slippery slope becomes a hard fall,” cautions Anderson. “As long as we’re willing to work towards managing those issues and use conservation tillage, and as long as the income stream is there, it’s workable.”
Livestock helps diversify
One of the byproducts of this residue management issue is the demand it may create. Kevin Eisses, who operates Hewitt Creek Farms near Innisfil, Ontario, wonders if conditions will reach the point where growers must ask themselves whether they are farming corn and soybeans or residue?
“To me, it’s not sustainable if you don’t put something back and we’re doing that through manure or rotation using forages where you get a lot of fibrous root growth,” says Eisses, who is also a director with the Innovative Farmers’ Association of Ontario. “But I would think that’s not the norm in Ontario these days, especially the way some livestock farms in this area have gone.”
Eisses is quick to add that in spite of any increase in commodity prices, growers are still hard pressed to exact a living from the land and any money they can make back from selling off residues is a help. “Still, in the short-term, mining your soil is only going to work for so long, then you’re going to have to pay later on, because I’d think that your soil structure is going to fall apart,” he says.