Treatments with inoculant should have more root nodules than the other N treatments. Addition of N to inoculant should reduce the number of nodules. It will be interesting to see the interactions between the cultivars, populations, and N treatments. It is anticipated that soybean grown at the higher population will yield more than with a lower population, however there is a chance that at the lower population the plants will branch out and compensate to achieve a similar yield. It may be possible that when seed cost is considered it could be more economical to go with the lower population. It is also anticipated that the inoculant treatment and the nitrogen treatment will have similar yields. The inoculant treatment should be the more economical treatment.

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Objectives of the research
Objectives of the research were to evaluate yield and growth differences between five nitrogen (N) fertilizer management strategies applied to two soybean cultivars with different maturities grown at two plant populations and to increase the knowledge base of soybean practices in southwest North Dakota.

Completed work
The research was conducted at two locations in 2017 and 2018 however only data from the Hettinger location was recorded due to herbicide damage in 2017 in Dickinson. In 2018 the Dickinson site had issues with too high of nutrient levels and we also dealt with early frost in the region. The Dickinson site was a little further behind the Hettinger site in maturity at first frost and there was frost damage during pod fill that caused issues with pod filling. Due to this issue only data from Hettinger is included in 2018 as well. Information from this trial was disseminated at Western Dakota Crops Day in Hettinger on December 20th 2018 and was discussed with stakeholders throughout the season.
2017 and 2018 results
There were some differences between some of the treatment interactions that need to be further investigated before making any conclusions. In 2017, no significant yield differences were found between populations. 80,000 plants/acre averaged 23.3 bu/ac while 160,000 plants/acre averaged 24.2 bu/ac. In 2018, 160,000 plants/acre yielded significantly higher at 27.1 bu/ac compared to 25.4 bu/ac in 80,000 plants/acre however depending on seed input costs and soybean price this may not necessarily result in higher profits.
Drought conditions in 2017 reduced yield capacity for soybeans. Under drought conditions a plant population half of the recommended seeding rate was able to yield just as well as the full rate. While it may be possible that with higher rainfall a larger yield is possible, more work should be conducted before changing recommendations. Under drought conditions with a reduced yield potential, it could be possible to reduce seed input costs without losing bushels and depending on the economic environment it may still be profitable to decrease plant population.
The trial will be continued in 2019 with locations planted in Dickinson, Hettinger, and Mandan.