In this video series on fertilizer return on investment, The Western Producer talks with three fertilizer researchers: Rigas Karamanos, Jeff Schoenau and Tom Jensen. Accompanying stories can be read below.
Part one of our multi-part series Fertilizer Return on Investment.
Fertilizer won’t pay off without a plan
Producers have the financial wherewithal to take some chances with increased inputs when commodity prices are higher and margins can cover all the costs of farming.
These strategies pay off to a point: yields increase and with them margins.
However, at some point levels of nutrient application result in a yield curve that flattens out, and the return on investment ratio falls.
Determining that sweet spot before the rate of gain diminishes too much and the risk of loss becomes too great is governed by science. However, knowing how and where to apply that science is the art of farming well, say agronomists.
Rigas Karamanos has spent his career researching and advising producers in Western Canada about crop nutrition and soil fertility.
“It all starts by knowing what you have: what your soil is capable of, what your genetics are capable of,” he said.
Karamanos, who is an agronomist with Koch Industries, said many producers tend to think about what they can live with when it comes to cost of production rather than what the crop can live with.
Jeff Schoenau of the University of Saskatchewan agreed.
The researcher feels producers should begin their crop planning by thinking about what they are building on and what it will take to produce big yields.
“If the goal is, and I am not saying you will all get there, 70 bushel (per acre) canola this year, have you considered what it will take, besides a lot of moisture?” he said.
“Canola will use 70 pounds of (nitrogen), 120 lb. of phosphorus, 180 lb. of potassium and 40 pounds of sulfur. You don’t have to put it all in with the crop, but that is what it needs to take out.”
Schoenau said producers can then begin to plan to maximize their yields, depending on what the soil has in it ahead of seeding time and what it is capable of supplying throughout the year from mineralization, release from previous crops and leftover fertilizer.
Karamanos feels most producers do “a pretty good job of replacing phosphorus” in most of their fields.
“But they do come up short in heavy canola or soybean rotations, where the crop is sensitive to those products and single pass operations can’t always allow (for full replacements). It might be worthwhile looking at their own recent cropping history to examine what has come out of their soils in recent years,” he said.
“We’ve had some historically huge crops in the past few years, and some huge rainfall and flooding. Can you tell me that you know what is out there in your fields? I think most can’t.… That is a base on which you can start to build a plan.”
Karamanos feels too many producers are still approaching their fertilizer strategy based on replacing what they think they removed from the field.
Recent research at the U of S has started to turn up high amounts of variability in long-term reduced tillage fields.
Schoenau said the old rules about sampling might not be as effective at determining what is really happening below the surface.
“There can be a lot of residual P in those old seed rows,” he said.
“We found as much variability in 100 centimetres (radius) as we did over an entire field.… We had to core 40 samples for P and 60 for N to get representative sample for the field.”
Researchers also discovered that fields using variable rate fertilizer systems had dramatically reduced variability when the same soil test criteria were applied.
Karamanos said not every field needs a soil test every year, but growers should plan for it regularly so that they can establish a baseline.
“The other thing they don’t often consider is the amount of moisture that is present in the soil,” he said.
“Not many can tell you what their reserves are and how much crop that will support. If you know what you have and can predict average amounts, you can plan a fertility strategy around it.”
Part two of The Western Producer’s four episode series on fertilizer return on investment
Nutrient management important following big crops
Getting fertilizer right can be a challenge.
Multiple cropping histories, variable moisture and soil, spring temperatures and the timing of applications makes choices complicated, but not impossible.
“Doing nothing, that can be a problem,” says Rigas Karamanos of Koch Industries.
“Providing replacement of what you are taking out is the basic thing you can do. And you need to do it over the long term. But addressing more specific, site specific needs for each crop in each field, that will allow crops to grow to their potential.”
A big crop removes a lot of nutrients. Prairie farmers have seen some of their largest crops in history over the past five years.
“What does a 70 bushel wheat crop remove? I can tell you, it’s a lot,” Karamanos said. “The soil provides some, the farmer provides some. But if you get that big a crop, it had to come from somewhere and you need to make a plan that will put it back if you want it to happen again.”
For example, a large canola crop of 70 bu. per acre requires 200 pounds per acre of nitrogen, 120 lb. of phosphorus, 180 of potassium and 40 of sulfur.
“The plant residue will put some in. The soil will mineralize some, especially with some of these 20-year plus no-till fields we have now, if there is moisture. The rest is up to the farmer,” he said.
Nitrogen and sulfur are highly mobile, but the movement of other macronutrients is restricted by their chemical nature.
In some cases, nutrients are not even largely available in the year of application.
“Your phosphorus is mostly for next year, but if you don’t make a deposit into that account this spring, it will hurt you next year, and the year after that,” Karamanos said.
“Farmers need to apply nutrients that get tied up or need time to become available, with a longer term plan.”
Soil scientist Jeff Schoenau of the University of Saskatchewan said producers need to think about how their plants will find potassium and phosphorus in the soil.
As well, they need to consider what will happen to the plants when they do.
“Too little and you pay. Lower yields. Too much and you damage germination and emergence,” Schoenau told producers at the recent FarmTech conference in Edmonton.
He said producers know they have to keep rates down with vulnerable crops, but they often won’t push the phosphorus rates when growing wheat and other cereals.
Recent University of Saskatchewan research in chernozem soil near Central Butte, Sask., and grey to black, luvisol soil near Melfort, Sask., has shown that wheat exposed to 12-51 in the seed row stood up to 40 pounds of the nutrient.
Thirty lb. is typically acceptable in canaryseed, 25 for canola and mustard and 20 for flax. Brome grass, peas and alfalfa seed are at the most sensitive end of the scale at 10 to 15 lb.
“So you can tell which rotation you want to put the P into,” he said.
Wheat is also tolerant of extra nutrients, such as potassium. With many crops, however, research has repeatedly shown that equal amounts of phosphorus must be removed when it is added, or seedlings will suffer.
There is a higher potential for plant injury when it comes to sulfur in dry, sandy, high pH soil.
It is possible to seed place 10 to 20 lb. of ammonium sulfate per acre in a moist soil of neutral pH with a loamy texture. In those conditions, it was found that Invigor 5440 canola saw a three percent reduction in emergence after two weeks with a seed placement of just 10 lb. of 21-0-0-24 when compared to no fertilizer at all.
That fell to 92 percent at 20 lb. and 68 percent at 30 lb. Producers can expect to drop another 10 percent in plant count when adding 15 lb. of 12-51-0-0, MAP to the seed row.
Argentine canola is more tolerant than Polish types and sister crops such as camelina to damage from fertilizer applications.
“You need to feed the crop, but at what cost?” Schoenau said.
He found that napus canola could handle relatively high mixes of nitrogen phosphorus and sulfur in the seed row as an MES-15 fertilizer prill formulation. Plant emergence didn’t drop off until applications had exceeded 30 lb. of sulfur, 66 lb. of phosphorus and 26 lb. of nitrogen with the seed.
“But if you are having to choose between your P and S in the seed row, I would put the mobile sulfur off to the side in a separate band if you can and keep the P (with the seed),” he said.
Research at Central Butte found that elemental sulfur forms delivered a limited amount of sulfur to the crop in the year of application.
“We knew it was lower, but using PRS (soil probes from Western Ag), we looked at it over eight weeks and saw poor (release),” he said.
Producers who need the sulfur in the year of application must use more available forms of the nutrient, he added.
Karamanos said producers should look to soil tests to set a benchmark for a field so that they know what applications are needed to meet crop demands.
“Know your water supply. Know your nutrients. Build from there,” he said.
Schoenau’s research last year found high variability in soil tests, especially when it came to phosphorus levels. Monolith samples that captured soil in blocks, rather than in vertical cores found that “there is a lot of old residual P in the fields, in those old seed rows.”
“We saw much variability in 100 centimeters as we found in the whole field. So take samples over a 30 cm (per core) on P (and potassium) and 60 on N (and sulfur and average them). We had to core 40 to 80 cores (per field) to get a proper sample. We compared variable rate to constant rate of application (fields) and we found the variable rate smoothed out the nutrient variability across those fields.”
Part three of the Fertilizer Return of Investment series
Bumper crops last year took toll on soil nutrients
Producers looking for top yields might find that previous good crops and traditional fertilizer strategies have plundered their soil bank accounts.
“It’s amounts in, amounts out, and that is very important to look at over the long haul,” said University of Saskatchewan soil scientist Jeff Schoenau.
Big crops are one cause of nutrient depletion in the soil, but low commodity prices and high fertilizer costs can also play a role in reducing nutrient availability.
Rigas Karamanos, a fertilizer researcher and agronomist with Koch Industries said producers must remember that those large crops have removed a lot of nutrients from the soil and it took time to get some of them there in the first place.
“You take a 60, 65 bushel canola crop, and this isn’t unheard of any more, and you took 60 pounds of phosphorus from the field. Did you replace that? How do you replace that? Producers need to consider these issues.”
He said rotation choices can also cause serious problems.
“Canola, canola, canola or canola, canola, wheat, canola. These can pull tremendous amounts of nutrients like phosphorus from the soil,” Karamanos said.
“Rotations can be critical to making your soil deliver for your crops.”
Jeff Schoenau said more farmers should consider their crop rotations as a way to deliver nutrients.
“There is a lot of merit in looking at your rotation to help reduce your fertilizer costs,” he said.
“Even, for example, forages in a rotation, even in the short term, a couple of years of alfalfa or clover.”
Recent work that Schoenau was involved in at the Western Beef Development Centre has found that an alfalfa crop, especially where moisture wasn’t limiting, such as Melfort, Sask., provided a nitrogen fertilizer value to subsequent crops of 200 to 300 lb. per acre.
“Having that legume in the rotation, even though that forage takes more phosphorus out of the soil, in fact the available phosphorus levels were maintained and the soil was able to supply phosphorus to the following crops, even without any phosphorus fertilizer in a reasonable proportion,” said Schoenau.
He said the alfalfa crop was likely recycling phosphorus from deeper in the soil’s profile, where annual crops can’t normally reach.
In 2008, North American farmers were confronted with phosphorus prices that exceeded $1,000 per acre. It caused many growers who had regularly applied it at 30 to 35 lb. per acre to stop applications. Many pulled rates back to 10 lb. as a starter kick for the crop and then reduced levels for a year or two until prices returned to sustainable levels.
Karamanos said most crops usually receive only half the nitrogen in a given year, “maybe see between 15, 35, 40 percent of their phosphorus, maybe half of their sulfur fertilizer. It depends on the crop and the year’s conditions. But when you fail to apply it, you develop other issues over time.”
Schoenau said he also reduced his phosphorus applications when the price spiked.
“A few years (later), you have to put that back,” he said.
“Lots paid the price for that later on. You don’t want to have that crash a few years down the road. (Set) up a plan that takes into account big crops, years when you didn’t put in all that you should.”
Fields with a history of reliable nutrient application actually have a greater capacity to pull nutrients from the soil through the breakdown of soil organic matter and crop residue.
Keeping crop residue on fields and tillage to a minimum can deliver more than just improved water holding capacity.
Some producers can derive good value from straw, but it can be a balancing act.
Part four of the Fertilizer Return on Investment series
Proper fertilizer placing pays in nutrient play
Tom Jensen from the International Plant Nutrition Institute in Saskatoon said livestock producers can replace nutrients and other soil improving features that are lost to straw removal by spreading manure on those fields.
“That is recycling the material,” he said. “In those areas where we are removing the straw and not putting back those nutrients, we can short the soil, especially in potassium.”
Schoenau said the seed portion of the crop takes with it high percentages of nitrogen and phosphorus. The crop’s residue contains higher levels of potassium and about half the sulfur.
Tom Jensen of International Plant Nutrition Institute says researchers found more than 25 years ago that anhydrous ammonia was pound for pound more effective than broadcasting fertilizer. It turned out it was the banding that was the key to the success.
However, it meant a second application step, and producers’ appreciation for single pass seeding solutions grew as they moved to reduced tillage and increased acreage.
Putting mobile nutrients such as nitrogen and sulfur in a band that is a plant-safe distance to the young seedlings was a first step.
The less mobile nutrients, such as phosphorus and potassium, need to be placed in the path of plant.
“If you broadcast the phosphorus, the way you might nitrogen, you have to use twice the rate to get the same uptake into the plant if you had placed it with the seed,” Jensen said.
“The same thing goes for potassium, copper and zinc,” he said.
Banding helps reduce nitrogen losses to the air or heavy rain events.
Jeff Schoenau of the University of Saskatchewan said liquid 28-0-0 UAN can be dribble banded, while NH3 can be effectively applied in the fall.
Jensen said farmers in the U.S. corn belt have a longer season to evaluate their crops and feed them with split applications of nitrogen.
Farmers in Western Canada and the Great Plains states can get almost the same results from a well-placed fertilizer supply during seeding.
“Split applications can be very effective if the weather supports it, but broadcasting some urea, or streaming some UAN down, can result in having it stranded at the soil’s surface it turns dry,” he said.
Schoenau said an early growing season application of top-dressed nitrogen will tend to boost yields, provided it reaches its targeted plants, while a later application will tend to boost protein in cereals.
Rigas Karamanos of Koch Industries said deep banding mobile nutrients remains the gold standard for low losses and effectively reaching crops.
However, a growing list of methods are available that can protect young plants while allowing high rates of otherwise toxic fertilizer to be applied in or beside the seed row. These tools can also help stabilize nitrogen when it is top-dressed, or even in a fall-banding program.
Polymer and sulfur coating are the two main systems. They create a physical barrier between the plant and urea and blocks and slows its breakdown in the soil.
Coated products rely on soil moisture to diffuse through the coating and break it down, releasing the nutrient within. Temperature also plays a role.
Water-insoluble, semi-permeable and impermeable material delays the release of nitrogen from the urea. Thickness, total coverage and uniformity of the coating on the granule are critical to plant safety and timing of the product’s release.
Poly coatings are not significantly affected by soil properties such as pH, salinity, soil texture, microbial activities or cation exchange capacity. The coating makes it possible to more accurately predict the nutrient release rate from those products when compared to sulfur-coated urea and stabilized products.
“If you want to put very high rates of fertilizer down with the seed, in one pass, you need to go with polymer products for the ultimate protection,” Karamanos said.
“When you are broadcasting, some of our environments are wet enough for the polymers to be released.”
However, he said nitrification inhibitors are more effective for broadcasting and streaming in most cases in Western Canada, whether in fall or as top-dressed product.
“Stabilized products are not the same thing. What they do is inhibit the urease, so it doesn’t convert the urea into ammonium or they inhibit nitrification. Some of the nitrogen inhibitors are bacteria-static, which stop the bugs, while others are bactericides,” he said.
“It doesn’t mean they won’t come back, but it slows the local processes.”
Jensen said losses can be as high as 40 percent if urea is broadcast onto damp soils and warm, dry windy conditions follow.