Blog: Agronomy & Extension

I think I have hard water, should I be adding AMS to my herbicide spray mix?

Coles Ag on June 2, 2026

MCA_AoA Headers WHOLE FARM

By Ashley Ammeter, Whole Farm Specialist, Manitoba Crop Alliance

Water quality can play a significant role in pesticide performance, but it’s a consideration that often flies under our radar until a herbicide application doesn’t work as well as we hoped. If you suspect hard water, adding ammonium sulphate (AMS) could the right call, but first it’s important to know what’s actually in your water. 

Start by testing your water

The first step in managing potential spray water issues is to test your water. While it’s generally good practice to test your water quality, it’s even more important if you suspect that poor water quality is affecting the performance of your herbicides. Agricultural spray water analyses are offered by many accredited agricultural laboratories, such as AGVISE Laboratories, A&L Canada Laboratories, Central Testing Laboratory and Horizon Lab.

Once you have a water quality test, Sprayers 101 has a helpful article on how to make sense of your water quality test results.

Why is hard water a problem?

Hard water contains high levels of positively charged minerals such as calcium (Ca2+), magnesium (Mg2+) and others. These minerals bind to herbicide molecules, preventing them from being absorbed by the plant and reducing efficacy.

Glyphosate (e.g., Roundup) is commonly associated with hard water antagonism, but hard water can reduce the efficacy of all weak acid herbicides (found in Groups 1, 2, 4, 6, 9, 10, 14, 19 and 27).

How much hardness is too much depends on the herbicide, rate and water volume you’re using. For glyphosate, Bayer suggests a hardness limit of up to 700 ppm, when using higher rates or lower water volumes.

Should you add AMS?

If you have hard water but don’t have access to an alternate water source, adding AMS is an effective strategy.

When added to spray water before your herbicide, the negatively charged sulphate ions in AMS tie up the hard water cations before they can antagonize the herbicide. To calculate how much AMS to use, Sprayers 101 has a helpful calculator, but many agriculture labs that offer spray water tests will include AMS recommendations in your test results, and herbicide labels or the Manitoba Agriculture Guide to Field Crop Protection often include water quality recommendations.

In some cases, reducing water volumes and/or increasing your herbicide rate can help counteract the effects of hard water, but always make sure to stay within label guidelines. 

Other water quality issues to be aware of

Along with hardness, there are a few other water quality factors to keep on your radar:

  • Dirty water (turbidity): Particles of soil and organic matter can bind herbicides and reduce performance. Clean water is particularly important for herbicides that are known to strongly bind to soil, such as glyphosate and diquat (e.g., Reglone).
  • Bicarbonates: Bicarbonate ions can inhibit herbicides, particularly the Group 1 “dims,” including clethodim (e.g., Select, Centurion) and tralkoxydim (e.g., Achieve) and the Group 4 herbicides MCPA amine and 2,4-D amine.
  • pH (acidity or alkalinity): The pH of your spray water can impact pesticide solubility and breakdown. Unless recommended on the product label, it is generally not advised to adjust the pH of your spray solution. For those interested in learning more, Sprayers 101 has a helpful article.

My last piece of advice: always read and follow the directions on your pesticide label. While they can be long and unwieldy, the pesticide label includes key details on how to use your herbicide safely and effectively.

Learn more

Does applying a fungicide at herbicide timing to control cereal leaf spot diseases in wheat and barley provide a yield boost?

Coles Ag on June 2, 2026

MCA_AoA Headers CEREALS

By Andrew Hector, Agronomy Extension Specialist – Cereal Crops, Manitoba Crop Alliance

This question comes up regularly, which makes sense. Early season outbreaks of fungal leaf spot diseases such as tan spot do occur in Manitoba, such as in 2024. But to really answer this question, we need to dig into some western Canadian research.

There have been a few studies done in Western Canada over the last 15 years investigating this very practice in both wheat and barley.

  1. The impact of fungicide and herbicide timing on foliar disease severity, and barley productivity and quality
  2. Evaluation of disease, yield and economics associated with fungicide timing in Canadian Western Red Spring wheat

In both these studies fungicide application timings were evaluated on their impact on leaf spot disease severity, overall crop yield and economic returns of the practice. In both studies, it was found that a foliar fungicide application at herbicide timing (2-3 leaf or 5 leaf) did not lower upper canopy disease incidence and severity compared to the check (no treatment or herbicide only). It was also found that the foliar fungicide treatment at herbicide timing didn’t improve crop yield compared to the untreated or herbicide only check. This ultimately led to an economic loss. In both studies, researchers found that foliar fungicide application timings for cereal leaf diseases should be aimed at protecting the upper canopy and yield-contributing leaves.

There has also been some research on this topic out of North Dakota. Andrew Friskop from North Dakota State University recently compiled replicated foliar fungicide timing trial data from 2008-2024. He evaluated the yield response based on “disease risk” scenarios determined by previous crop, variety resistance, tillage, environmental conditions and disease onset.

Figure 1. NDSU disease risk categories for development of residue-borne foliar diseases.

His finding suggests that under high-risk scenarios, (where wheat was grown on wheat stubble, a susceptible variety was planted and the disease [tan spot] was established early and firmly in the crop), a fungicide application at tillering could provide a small benefit of 2.2 – 3.7 bu/ac. In basically all other production scenarios he found that a foliar fungicide application at tillering would provide very little yield response.

Figure 2. Summary of yield response by disease risk level for early season fungicide application.

What is the difference between GDD, CHU and RM? Why and when are they each important?

Morgan Cott on June 1, 2026

MCA_AoA Headers SPECIAL CROPS

By Morgan Cott, Agronomy Extension Specialist – Special Crops, Manitoba Crop Alliance

This is such a great question and I understand the reasons for asking. First of all, I think it is understood that GDD & CHU both basically measure how efficiently a day’s heat will benefit a growing or developing crop. One main difference between the two measurements is that CHU does account for extremely high temperatures (>30oC) that negatively affect crop development. CHU also looks at both the nighttime low temperatures (4.4oC as the base) and daytime temperatures between only 10oC (base) and 30oC (optimum ceiling).

GDD has historically been used to help estimate certain agronomic events like insect emergence, weed emergence, frost-free days and specific crop staging. My understanding is that CHU is used more for maturity than for the ability to accurately predict these different timelines throughout the season. This might be why certain seed companies use CHU and RM for maturity ranking and GDD for staging references.

Pride Seeds is an example of this, because they break down maturity with both CHU and RM, in addition to two key reproductive stages in GDD accumulation.

PRIDE hybrid

When calculating GDD or CHU, you will start from the day after corn was planted. It takes from 100 – 120 GDD for corn to emerge following planting, which is in ideal conditions, including soil moisture and soil temperature, which were variable this spring (and every spring). Start your calculations from day 1 until the day of emergence and see if that fits the above. Now that corn has emerged and is actively growing in your current conditions, continue to monitor accumulating GDD with the following formula. This will give you a head start on expectations during the growing season. When to expect pollination, for example. Note that this GDD accumulation in relation to corn staging is all in relation to each individual hybrid. A shorter season hybrid will need fewer GDD or CHU to reach black layer than a longer season hybrid, of course.

GDD formula
CHU formula

 

Helpful Resources:

I’m switching my wheat variety; do I need to change my seeding rate?

Andrew Hector on May 5, 2026

The short answer is yes; you will most likely need to change your seeding rate, but this is not just because you are planting a different wheat variety. Rather, seeding rates should be adjusted annually to reflect seed source characteristics (germination, thousand kernel weight [TKW]) and the environment the seed is being planted into, to ensure you can achieve your target plant population.  

Let’s dig into why this is. For spring wheat, provincial target plant population recommendations are between 23-28 pl/ft2, with many producers targeting the upper end of this recommendation. Achieving your target plant stands sets your crops up for success, as crop uniformity is improved, weed pressure is combatted and resources are optimized.  Seeding rates should be calculated to achieve your target plant stand, which means accounting for germination percentage, expected mortality and, importantly, your TKW. TKW changes year-to-year and from variety to variety.

Let’s consider an example to illustrate the relationship between kernel weight and seeding rate. For this example, let’s call our two varieties variety one and variety two. When comparing these two varieties we need to consider:

  • TKW: The weight (g) of 1,000 kernels of wheat from a specific seed lot.
  • Germination: If using bin-run seed, a seed test is needed to determine germination percentage. If purchasing certified seed, then your seed provider will be able to provide you with this information.
  • Expected mortality: The percent of seed/seedlings that won’t produce a plant due to unfavourable conditions or biotic stress.
  • Expected seed survival: Germination – Expected Mortality.

Example #1:

Variety

TKW

Germ (%)

Expected mortality (%)

Expected seed survival

Target plant density (pl/ft2)

1

42

97

6

91

27

2

33

97

6

91

27

Using the formula provided by Manitoba Agriculture (below) we can see the difference in seeding rates and therefore seed costs.

Seeding by plant population formula:

Seeding rate (lb/ac) = Target Plant Population (pl/ft2) x TKW (g)

                                              Expected Seed Survival (decimal) x 10

 Variety 1:

Seeding rate (lb/ac) = Target Plant Population (pl/ft2) x TKW (g)

                                              Expected Seed Survival (decimal) x 10                                          

                                                         = 27 (pl/ft2) x 42 (g)

                                                                     0.91 x 10

                                                         = 125 lb/ac

Variety 2:

Seeding rate (lb/ac) = Target Plant Population (pl/ft2) x TKW (g)

                                              Expected Seed Survival (decimal)

                                                         = 27 (pl/ft2) x 34 (g)

                                                                     0.91 x 10

                                                          = 101 lb/ac

This example shows that there is roughly a 24 lb/ac difference between the two seeding rates to achieve the same desired plant population. If you seeded variety 2 at the same rate as variety 1, then you would have over seeded, which could result in a thicker canopy, bringing challenges like an increased lodging and disease development risk.

Also, over seeding would have cost you money. Using a standard seed cost of 0.27 ¢/lb of seed (Manitoba Cost of Production Guide), then variety 2 at your normal rate would cost an additional $6.5/ac of seed that is probably not needed to reach your desired plant population.

Now, if the weather, disease, insects and equipment co-operate, you’ll achieve your target plant population. But it’s always best practice to do plant counts to get an understanding of the crop establishment and uniformity of emergence. More information on plant stand counts can be found here: Plant Stand Counts in Spring Cereals | Manitoba Crop Alliance.

Should I be looking at biologicals to offset high fertilizer costs?

Ashley Ammeter on May 5, 2026

First, let’s clarify what we mean when we’re talking about biological products. This is a broad group that includes both naturally occurring substances (such as humic or fulvic acids, seaweed extracts and enzymes) as well as beneficial microbes (such as nitrogen-fixing bacteria, phosphorus-solubilizing microbes, plant growth promoting rhizobacteria and mycorrhizal fungi). These products aren’t fertilizers themselves, but often claim to increase nutrient availability, improve nutrient uptake, improve stress tolerance or support plant growth.

Since high fertilizer prices have prompted some renewed interest in these products, I’ll focus mainly on nitrogen-fixing biologicals.

A quick note on regulation (and why it matters)

In Canada, most of these products are regulated under the Fertilizers Act. That means they must be properly labelled and prove that they are safe, but they do not need to prove efficacy before being sold. This makes replicated, independent research particularly important to test whether a product increases yield or can replace fertilizer under Manitoba conditions.

What has local research found?

Through our Research on the Farm program, MCA has tested a nitrogen-fixing biological product (Envita®) in several replicated, field-scale strip trials. In the eight corn and two spring wheat trials, we did not find a statistically significant yield increase when the nitrogen-fixing biological product was used.

Through their On-Farm Network, our colleagues with Manitoba Pulse and Soybean Growers (MPSG) have also tested many biological products. In 46 trials evaluating a range of microbial and non-microbial products, no statistically significant yield increases have been observed.

That doesn’t mean these products can never work. It does mean that predictable ROI has been hard to find under Manitoba conditions.

Does small‑plot research tell a different story?

Not really.

University and independent research in Western Canada and the North Central United States to date has largely lined up with what MCA and MPSG have found in on-farm trials. There are occasional positive responses, but they’re sporadic and can be hard to predict. For example:

Why are results so inconsistent? Formulation challenges, competition with the native microbial population and environmental differences all influence whether a product will find success. For those interested in learning more on this topic, Andrew McGuire with Washington State University has an interesting article.

So, should you use biologicals to offset high fertilizer costs?

Biologicals are an active area of research, and some products may eventually find a fit in our cropping systems. But based on local on‑farm and small-plot research to date, they are unfortunately not a silver bullet for high fertilizer prices.

If you do want to try a biological product, think about what problem you’re trying to solve. Is it a nutrient deficiency? Are you hoping to mitigate environmental stress? Are you trying to improve your long-term soil health? Consider the product claims, what the active ingredient is and how the product claims to work. Finally, if you do decide to try a product on your farm, I encourage you to consider conducting a replicated strip trial. Replicated strip trials let you test a product on your own farm, with your own management, and give statistically valid results. If you want to learn more about conducting on-farm trials, reach out to us for more information on the MCA Research on the Farm program.

The bottom line: For now, I recommend approaching biologicals with curiosity, caution and solid, on‑farm testing. To ensure you’re making efficient use of your fertilizers, use the 4Rs of nutrient stewardship (the Right Source @ the Right Rate, Right Time, and Right Place®) to guide your decision making, and check out this helpful factsheet on stretching fertilizer dollars and supplies from Manitoba Agriculture.

How much 10-34-0 can be applied with my corn seed?

Morgan Cott on May 5, 2026

Oddly, I have had this conversation more this winter/spring than ever before. On paper, there is a finite answer. Anecdotally, there are a few different options and it is all dependent on soil type and soil conditions, moisture, etc.

First of all, side-banding any type of fertilizer is much safer than placing it with the seed. Some fertilizers are safe in certain quantities with the seed, but very few. Side-banding is much safer and provides quick access to the roots. Midrow banding is the safest method, but roots take that much longer to access the fertilizer row, which negates the “starter” effect. The other factor that indicates the level of safety is soil moisture; the drier the soil, the more risky it is to place any fertilizer with or near the seed.

I’m guilty of thinking that fertilizer toxicity to the seed is mainly due to the nitrogen content and a result of ammonia burn. Salt injury is actually more common and affects germination and early season growth, so applying fertilizers that have a low salt index in closer proximity to the seed is best, if any has to be close to the seed at all. Bonus points if there is good soil moisture at the time of fertilization.

As I mentioned, on paper there are defined rates of 10-34-0 that can safely be applied in-furrow with corn on 30” rows. This table shows those rates and placement that will help to avoid salt injury to the corn crop.

Table: Amount of 10-34-0 (gal/acre) to help avoid salt injury to corn grown in 30” rows.

After having some discussions with Manitoba corn farmers on various soil types, I did get some reasonable responses explaining increasing rates in heavier, wetter soils. But more importantly, decreasing the above rates in dry and/or lighter soils. These were purely anecdotal and not research-based.

I recommend being very conservative in 10-34-0 rates if you are new to trying this method of application, and especially if you are planting in dry conditions and/or coarse soil textures. Start small and have many conversations with your peers on their experiences with various rates of 10-34-0 in-furrow. Use that information to make a conservative decision of your own.

Remember, start your season with success and make smart choices. Do not make decisions that could get your crop off to a bad start. We live in Manitoba – Mother Nature is hard enough on us in spring.

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