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Evaluating Stand Establishment in Small Grains (05/12/16)

Last week we summarized some of the findings from a large spring wheat seeding rate trial conducted over the last three seasons in North Dakota and Minnesota.

Evaluating Stand Establishment in Small Grains

Last week we summarized some of the findings from a large spring wheat seeding rate trial conducted over the last three seasons in North Dakota and Minnesota. We failed to include in that report that the optimum seeding rates recommended were viable seeds per acre and not emerged plants. Ultimately only plants that establish will contribute to the yield potential of a field. Nevertheless, the seeding rate recommendations arising from the previously discussed research were derived from the number of seeds sown and not the number of established plants. In that study we did observe fairly large differences in the amount of viable seeds that actually established plants. Averaged across locations and seeding rates, 15% of the seeds planted failed to develop into seedlings (for the purpose of this article we will refer to this as stand loss). The range in stand loss varied from 5.1% in Perley in 2014 to 46.6% in Lamberton for the second planting date in 2014. One other location had a stand loss in the 40s (Prosper), and there were three environments in the 20s. The median for stand loss across all the environments was 10.5%. As you can see from these data, environment plays an important role in the stand establishment of small grains and it is not always easy during the planting process to know what kinds of challenges will impact germination and emergence in a given year. The very poor stands in the two locations with the poorest emergence in our study could be traced to excessive moisture prior to emergence at one location and mudding in the planted seed at another. We also observed a greater reduction in establishment as seeding rates increased. This phenomenon has been reported by other researchers.

This year there have been numerous reports of emergence problems due to crusting. Many of our small grain trials this year were planted just before the heavy rains. Heavy rain combined with tilled soil with limited aggregation is a perfect combination for crusting, so now we are dealing with the effects of crusting at several of our sites. In locations with crusting we have observed up to 35% stand loss. This level of stand loss will cost us some yield. The amount of yield reduction, as we learned from our study, will depend on how the rest of the season develops. Yield losses in the seven lowest yielding environments (out of 21 total environments) averaged 5% from the optimum seeding rate for maximum yield to the lowest seeding rate of 600,000 seeds per acre. In the top seven yielding environments, yield losses for the same scenario were only 3%.

For those with stand establishment issues that are wondering if replanting might be a better alternative to keeping a poor stand, we are including our current recommendation (from the Small Grains Field Guide). These guidelines are:

1-      If reduced stand is uniform (no big skips or holes) keep stands of 15 plants per square foot.

2-      If skips are large (3 to 6 feet) or holes are 4 to 6 feet in diameter and the stand is 18 plants per square foot or less, then replant if moisture is adequate.

3-      After June 1 replant with a crop other than wheat or barley since yields are reduced by about 50 percent when planting after this date compared to with a normal planting dates.

 

Joel Ransom

Extension Agronomist for Cereal Crops

 

Grant Mehring

Research Specialist

 

Jochum Wiersma

Extension Agronomist, U of MN

 

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