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Crop Advisor Casebook: Did John’s durum seed get burned by fertilizer?

A Crop Advisor's Solution from the February 6, 2018 issue of Grainews

Jessica Siemens.
photo: Supplied

John’s durum crop got off to a rocky start last spring with poor seedling emergence. John farms 16,000 acres of canola, durum, spring wheat, barley, peas and lentils near Stirling, Alta.

Early on, the stand was thin and patchy, which became more prevalent as the plants got bigger. Since the spring, I’d been keeping an eye on this field to see if it would outgrow its patchy, thin stand.

Early on, the stand was thin and patchy, which became more prevalent as the plants got bigger.
photo: Supplied

While I was scouting the crop, I noticed the plants in the patchy areas had become stunted, with purpling at the plants’ bases, since my last visit.

“I think I might’ve put too much fertilizer down in the seed row, and I’ve burned the seed,” said John.

However, when I dug up some seeds, I could see they had germinated, but the seedlings were yellow and kinked.

I didn’t believe we were dealing with a fertilizer issue, but to rule it out I checked seedbed utilization, fertilizer amount applied in the seed row, and moisture conditions at seeding. These factors were correct and conducive to proper germination.

I checked seedbed utilization, fertilizer amount applied in the seed row and moisture conditions.
photo: Supplied

Furthermore, there were no visual signs of fertilizer burn on the seeds. Because it was tested beforehand, we knew the seed was not the issue. Seed germination rate, vigour and disease levels were good.

John also provided a few other important details. For instance, the field was seeded a few days before heavy rainfall. In this field, the soil is clay loam. John rolled the field after seeding to push any rocks deeper into the soil.

I sent samples of the stunted and purpling seedlings to a laboratory for analysis, and for confirmation of my diagnosis of what was happening in John’s durum field.


Crop Advisor’s Solution: Watch out for soil compaction and crusting when rolling fields

The plants were suffering from phosphorus deficiency. Here’s what happened…

The heavy precipitation and soil compaction, which was caused by the rolling, resulted in the crusting of the soil’s top layer. This soil compaction and crusting caused poor seedling emergence in the affected areas. The seedlings were prevented from breaking through the soil surface, resulting in the plants’ squiggly-like growth and yellowing.

Those seedlings that did emerge through the soil crust were stunted and purpling. Here, the plants’ limited root growth, caused by the compacted soil, resulted in phosphorus deficiency. Stunted growth and purpling at the plant base are often symptoms of this type of nutrient deficiency.

Plants in the patchy areas had become stunted, with purpling at the plants’ bases.
photo: Supplied

Land rolling should only be carried out on fields when completely necessary, especially when heavy clay soils are involved. Also, avoid rolling fields just prior to seedling emergence, ground crack, or when the soil is wet.

In John’s case, reseeding was not an economical option. Because the poor seedling emergence occurred in patches, and not consistently throughout the field, enough seedlings emerged to produce a crop.

That growing season, weather was also a challenge — the area received little rain and intense heat. Thus, this durum field only averaged about 30 bushels per acre. However, the yield was not significantly different from John’s other fields.

Jessica Siemens works for Richardson Pioneer Ltd. in Stirling, Alta.

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