Les Henry: New wrinkles when fertilizing grass crops for hay and pasture

One quarter section of fertilized grass could give the same yield as five quarters of “cut what is there”

Published: May 10, 2023

, , ,

A typical brome grass field of the many I drive by on the way to Dundurn Farm. In wet years, there are many bales and in dry years only a few bales. The rain or soil moisture is always needed but if fertility is missing, wet years become ordinary years not high-yield years.

There are many old grass stands that are mainly brome grass and serve as hayfields with occasional grazing. Many hayfields have never seen a kernel of fertilizer. Perhaps this piece will start folks thinking and will lead to a change in practice.

There are many old reports that deal with the topic. The two main actors in Alberta and Saskatchewan were John Harapiak of Westco Fertilizers and Harry Ukrainetz of Agriculture and Agri-Food Canada at Scott and Saskatoon, Sask.

If readers want to check out the original reports, they can visit the the University of Saskatchewan website and review the author’s works – John Harapiak and Harry Ukrainetz – dealing with fertilizing grass stands.

Read Also

Sclerotinia stem lesion. CCC photo

Good news, bad news for fungicides meant to fight stem rot in canola

A report shows overall insensitivity of sclerotinia to three fungicide groups hasn’t changed in a big way between 2010 and 2024 — but shows some sclerotinia populations have been discovered with elevated insensitivity to all three.

The punch line first

Figure 1 (below) says a lot. It is from Harapiak’s 30-year experiment with brome grass on Black soil north of Calgary. Apply 100 pounds of nitrogen per acre each year and the 16-year average is a fivefold increase in hay yield.

Grass response to N rates
Figure 1. This graph shows John Harapiak’s 30-year experiment with brome grass on Black soil north of Calgary, Alta. photo: Courtesy of Les Henry

That means one quarter section of fertilized grass could give the same yield as five quarters of “cut what is there.”

Imagine the possibilities.

Urea (46-0-0) and ammonium nitrate (34-0-0)

Ammonium nitrate was a great broadcast fertilizer as it was not subject to volatile loss of ammonium. We no longer have ammonium nitrate as a fertilizer in Western Canada. Ammonium nitrate can explode and was used in the Oklahoma destruction of a large government building many years ago. They still have ammonium nitrate in Ontario.

Urea is subject to volatile loss of ammonium but experiments by Ukrainetz showed the difference between urea and ammonium nitrate as a fertilizer for grass was not huge and often there was little difference.

Rainfall timing is a big issue. If you apply urea and an inch or more of rain comes along in the next day or two the urea is “washed in” and all is good.

If you have urea and a floater handy, and you have the flexibility to apply it just ahead of a significant forecast rain, volatile losses will not be a big issue.

I did that many years ago on my Dundurn farm with a sulphur-deficient canola crop. We floated on 100 pounds per acre of sulphate fines (21-0-0-24) when one inch of rain was forecast. It actually rained 1.75 inches and the sulphur response was evident in less than a week.

What about phosphorus fertilizer?

As shown in Figure 2 (below), Ukrainetz found that an initial application of approximately 80 pounds of P2O5 per acre brought hay yields to a new level. In recent years, we have learned the same thing will happen with annual crops.

Bromegrass Hay Response to N and P2O5
Figure 2. This data shows the effect of a one-time high phosphorus application rate to bring hay production to a new level. photo: Courtesy of Les Henry

What about applying very high nitrogen rates once?

A single application of very high nitrogen rates can result in many years of nitrogen response but there are some potential serious problems with that approach including the large initial outlay. High nitrates in the hay can be toxic to livestock and high nitrogen rates can make the soil acidic.

Fast-forward to 2022: Work by Sask Ag

At the Saskatchewan Agronomy Research Update meetings in December 2022, it was my pleasure to see a presentation by Jordan Johnson of Saskatchewan Agriculture in Swift Current.

In 2022, she completed fertilizer experiments on old forage stands at Weyburn, Sask., on a tough, Trossachs loam, Dark Brown, Solonetzic soil and on an Oxbow loam, Black soil at Yorkton, Sask. She used urea at 68 pounds of nitrogen per acre in a mixed fertilizer with phosphorus and potassium but included a urease inhibitor and nitrification inhibitor.

The results in hay dry matter in pounds per acre can be found in Table 1 (below).

Hay Dry Matter (Pounds per acre)
Fertilizer experiments conducted in Saskatchewan by Jordan Johnson on old forage stands at Weyburn, on a tough, Trossachs loam, Dark Brown, Solonetzic soil, and at Yorkton, on an Oxbow loam, Black soil. She used urea at 68 pounds of nitrogen per acre in a mixed fertilizer with phosphorus and potassium. Also included in the experiments were urease and nitrification inhibitors. photo: Courtesy of Les Henry

It is only one year of data but is interesting and worth a closer look. Thanks to Jordan for providing me with extra details. If readers wish to contact Jordan, you can email her at [email protected] or call her at 1-306 741-6800.

Getting started

To keep it simple, you can start by broadcasting urea (46-0-0) at approximately 220 pounds per acre, which will give you about 100 pounds of nitrogen per acre. You can start with a few strips in a field or quarter section just to observe the response. Do it early in the spring or just before a significant rain forecast. Rain is needed to wash the urea to the roots.

On very sandy soils, potassium may be a problem and on Grey Wooded soils sulphur deficiency is common, so a soil test is a good place to start.

Good luck and I hope you have a lot of work hauling away the extra bales of hay. As spring field work starts, always remember safety first, so you will be around to do the harvest as well.

About the author

Les Henry

Les Henry

Columnist

J.L.(Les) Henry was a professor and extension specialist at the University of Saskatchewan and a longtime Grainews columnist who farmed at Dundurn, Sask. Les passed away in 2024.

explore

Stories from our other publications