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High interest in humic acid

Each time fertilizer prices go up, as they did in 2009, curiosity about unconventional options also spikes. “There’s always a huge interest in alternative products when the price of fertilizer goes through the roof,” says Keith Reid, soil fertility specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs. “It will be interesting to see if that interest holds in 2010, when fertilizer prices are expected to come down.”


December 17, 2009
By Treena Hein

Topics
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With just one set of replicated trials on humic acid products completed, more research is needed to confirm their effects on yield.


 

Each time fertilizer prices go up, as they did in 2009, curiosity about unconventional options also spikes. “There’s always a huge interest in alternative products when the price of fertilizer goes through the roof,” says Keith Reid, soil fertility specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs. “It will be interesting to see if that interest holds in 2010, when fertilizer prices are expected to come down.”

Among the alternative products gaining attention, those containing humic acids are of particular note. “Only a few producers are dabbling with them, but there’s lots of interest,” says Reid. “Gypsum, kelp, molasses, there are lots of alternative products that have come and gone. The humic acids are still a bit fringe, but there is some suggestion there could be something to them – a credible explanation for the effects we are seeing.”

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Reid observes that although the mode of action of humic acids has not yet been pinned down, two possible mechanisms have been identified. “Perhaps they increase soil availability of nutrients,” he says, “or they might provide a hormonal effect on plants that helps increase their nutrient and water uptake. There is evidence for both of these.”

Most of the scientific research in Canada on humic and fulvic acid soil chemistry has been conducted by Dr. Morris Schnitzer, emeritus distinguished scientist at Agriculture and Agri-food Canada. Humic acids, fulvic acids and humin are the three main components of soil organic matter, he says. “Some parts of soil organic material are degraded quickly, providing something for bacteria to feed on,” Schnitzer notes, “but humic and fulvic acids stay in the soil a long time, which is also important.” He has found evidence that these acids increase soil availability of nutrients.

At the same time that some effects of humic acid products are being observed, however, Reid cautions that there is considerable variability in the effect of various humic acid products. “Humic acids are not a single compound, but a group of high molecular weight organic acids,” he says. “Every commercial humic acid product contains a different proportion. Some of them probably have a lot of chelating or hormonal activity, some will have no effect, and some may even be phytotoxic.”

Reid also observes there are “lots of cases” in which the same product has given inconsistent crop performance results, which he says is most likely due to variability in the manufacturing process. “Some of them appear to vary greatly batch to batch,” he says, “and that’s been a large barrier to humic acids becoming a large part of a crop production package for farmers.”
No fertilizers containing humic and fulvic acids are yet registered with the Canadian Food Inspection Agency. “That these products have not yet gone through the formal commercial fertilizer approval process is not to say they don’t work,” says Reid, “but it means the evidence to say they do work has not undergone formal scrutiny.”

12a  
 As growers continue to cultivate their fields, there is a greater need to maintain soil organic matter concentrations. Humic acid products may help.  
12b  
Spreading manure is the default option for many when it comes to adding organic matter to soil, but other options, including humic acid, are being studied. Photo courtesy of Margaret Land. 


 

Using humic acids
There are a number of important points to consider before trying humic acid products. At the outset, Reid cautions, “If you’ve got a nutrient deficiency, none of these products will replace fertilizer. Some livestock farmers are saying they’re getting great results and saving money with alternative programs, but they already have the nutrients they need on the farm.”

Laird Currie, crop advisor at Huron Bay Co-operative in Belgrave, Ontario, has tested Humika during the past several years and can provide some insight into the use of this particular humic acid product. Humika was created in 2001 by Arnold Wiegersma, owner of Alpha Agri-Products in Bluevale, Ontario. Humika is derived from lignite coal through a lengthy process.

During the course of three seasons of 20 acre long strip trials on winter wheat using a spring application of a 0.5 litres/ac of Humika with a full rate of fertilizer, Currie found that the treated strips gave an average of 5.5 bu/ac more. Currie has tried a similar test with a fall application once, which produced nine bushels more. In corn, Currie says that one year’s testing resulted in a three acre long test strip yielding an additional 20 bu/ac.

With regard to application, Currie notes “You can’t mix Humika with herbicides and pesticides because it’s not registered. You take a risk of what chemical it might produce (tank injury, crop injury and so on), so an extra trip with the sprayer is required. However, $8 for application and $8 for product per acre is a substantial return for money invested.”

Wiegersma says Humika works best on fields with less than five percent organic matter and should be applied at the same time that liquid starter fertilizer is used.

When asked for final thoughts on using humic acid products, Schnitzer says “Adding humic acid products to the soil is very good, but adding any soil organic matter that is not toxic is critical to maintain the soil and maintain high fertility, water content and soil structure. As we keep cultivating, we need to add a great deal of organic material back to soil. It is very important to keep the concentration up.”

Reid concludes, “Does it promote increased growth and yield? There are some results that are intriguing. It’s something we’re watching and looking for more data on. If it is one particular acid or group of humic acids, the question is, how would you extract or manufacture it? It’s from an organic substrate, so this is difficult.”

Reid believes the only way the crop-growing community will know if humic acid products definitively promote higher yields is with much more evidence. “It would be nice to see farmers do replicated field trials,” he says, where more than one test site is used in the same season. “The only replicated trial I’ve seen was done in 2008 with Humika, but I don’t get excited about just one year’s data.”