Seed & Chemical
Banding dry P and K fertilizer isn’t outdated
By Madeleine Baerg
If you are like most Ontario corn producers, you probably think applying a band of dry fertilizer at seeding is a completely outdated concept. And, unless your opinion strays far from that of your neighbours, you likely also believe reduced tillage is, if not an outright impossibility for your farm, at least an unnecessary inconvenience with downsides that outweigh the benefits.
But recent studies by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) suggest you may want to change your mind on both fronts.
“We’ve spent several years looking at a number of agronomic possibilities to improve corn efficiency,” Greg Stewart, OMAFRA corn industry program lead says. “On the fertilizing side, there are people who would say what we are proposing is a step backwards. But it doesn’t take a whole lot to convince them that applying dry fertilizer at planting could be a reasonable thing to do. And in terms of reduced tillage, we’re suggesting an intermediate step that works in harmony with the dry fertilizer concept.”
The majority of corn farmers today opt exclusively for injectable, liquid forms of phosphorus (P) and potassium (K). This choice can make sense, so long as the cropping land’s soil starts off with fairly strong levels of nutrients and only requires a minimal top-up. On land testing in the moderate to low range for P and K, however, a product like a liquid 6-24-6 fertilizer applied at a typical five gallon per acre rate will only contribute about 3.5 pounds of K per acre: not enough to bump up a deficient soil’s capacity to meet a corn crop’s nutritional requirements. A much more cost-effective way to easily apply larger amounts of P and K is to band dry fertilizer.
“If you are deficient in K, you can put on 10 times as much potash, and at a price that is much more competitive per pound, if you use dry fertilizer over liquid,” Stewart says.
Stewart suggests a four-point checklist when evaluating the impact dry fertilizer might have on your operation. Those four points are: soil test levels, soil structure, intensity of tillage and land tenure.
“If a grower has high soil test levels for P and K, has excellent soil structure, does fairly intensive tillage and owns all his land, then it is most likely that dry fertilizer won’t pay,” Stewart says. “But at the other end of the spectrum is the grower with lower testing soils and soil structure that still needs some improvement, who would like to do less tillage and who rents much of his land. In that case, dry P and K could be a very important factor in boosting corn yields.”
Most producers will fall somewhere in-between the two extremes, and will need to evaluate how much potential dry fertilizer might offer.
To minimize extra passes, Stewart suggests one of two dry fertilizer application methods, both of which may raise your neighbour’s eyebrows.
The first is to carry dry fertilizer on your planter. “People are spending huge amounts of money on corn planters that seem to be able to do anything: minutely control seed placement, adjust pressure, plant at 15 kilometers per hour, carry and switch back and forth between two seed varieties. And here some government guy gets up and says they should carry dry fertilizer on their planter. It’s kind of a 1970s concept: not very new, not very exciting ,” Stewart says. “But, based on the results from the studies we’ve done, in the realm of return on investment, it would be a mistake to completely ignore the concept of banding dry fertilizer beside the seedrow.”
Admittedly, there may be logistical hurdles to the concept, especially since today’s big planters often don’t have the capacity to carry dry fertilizer on board. In some cases, retrofitting a machine may only be a moderate investment, such as installing tubs across the front of the machine that each deliver dry fertilizer to just a couple rows. Alternatively, a planter without onboard capacity might require a separate pull-behind cart that blows fertilizer through tubes alongside seedrows.
“For some people, it’s just not going to be logistically possible to set up a workable system, even to tender the dry fertilizer to the planter. But, there are a large number of producers who shouldn’t dismiss this idea completely,” Stewart says.
A second option for applying dry fertilizer is to apply it prior to seeding (either in fall or spring) in an eight-inch tilled strip.
Conservation tillage for corn has had a difficult time gaining ground in Ontario. However, strip tillage solves the issue of residue and slow spring warming and drying, while still offering the soil health and environmental benefits of reduced tillage. And, when laid out on the contour (the strips cut horizontally across slope rather than vertically up slope), strip tillage can work as multiple mini dams to very effectively reduce erosion.
“Precision steering makes creating these eight-inch strips and then getting the corn rows on top of them suddenly quite possible,” Stewart says. “If you put your dry fertilizer on your strip tiller, when you come along with your planter the land can be exactly how you like it – absolutely naked. You just plant and go. There’s real harmony between the ideas.”
Initial trials last season, led by Stewart and the Innovative Farmers Association of Ontario (IFAO), showed some cost benefit from applying dry fertilizer during strip tillage. In the first year of trials, the results were not entirely consistent. The project will be continued in 2015 and updated results posted to the IFAO website.
“If we were careful, we could put all of our fertilizer into the strip zone in advance, which offered some cost savings. But, putting all of the N, P and K into that eight inch strip can make it too hot for seedlings, and softening the blow by switching to a polycoated urea added costs over and above conventional urea, which took away some of the cost benefit.”
Still, the environmental benefits, convenient timing of fertilizer application, and elimination of later season fertilizer broadcasting and knifing mean the system offers benefits beyond input dollars and cents.
“If we could get people to move to strip tillage, that would be a really good step forward, even if they are never going to switch all the way to zero tillage. It’s not necessary to move completely to no-till in order to see the benefits of reduced tillage. This is a new way of looking at field management,” Stewart says.
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