Planting date plays a significant role in crop production. Early or late planting may decrease grain yield and quality of a crop due to increased biotic (insect, disease, weed), and abiotic (frost, drought, and high temperature) stress. Western North Dakota has a semi-arid climate with an annual precipitation of <13 inches (excluding this year’s data), which is 5 inches lower than the eastern part of the state. There is a need of determining optimal soybean planting dates and soil temperature for the western part of North Dakota that provide optimum growing period, decrease chances of frost and/or drought damage, and enhance grain yield. We are proposing to repeat an experiment conducted in 2018-19, which showed that there was a significant difference among planting dates for plant stand and grain yield. The plant emergence per acre at the first planting date (May 3) was ~25% less than at the last planting date (June 15); and soybean planted on May 16 and 25 had a maximum grain yield of ~17 bu/a, which was on an average 3 to 6 bushels more grain than other planting dates. The outcomes of this research will validate our previous years’ findings. The research results will be communicated to clienteles through presentations at field days, workshops, and publications in electronic and printed formats. This project will enable us to provide pertinent information to producers of semi-arid western ND on a suitable soybean planting date and soil temperature that increase soybean yield, quality, and secure a profitable future.

a. To find out optimal soybean planting date for western ND.
b. To determine an optimal soil temperature (at 4” depth) for planting soybean at western
ND.

i. A technical report on the outcomes of the project.
ii. An Executive summary on the project.

Update:
Determining Suitable Planting Date and Soil Temperature for Enhanced Growth and Yield of Soybean Under No-till Semi-arid Condition
(Mid-Year Report)
Gautam Pradhan, PI
NDSU Williston Research Extension Center

Objectives
To find out the optimal soybean planting date for western ND.
To determine an optimal soil temperature (at 4” depth) for planting soybean at western ND.

Completed works
Two glyphosate-tolerant soybean varieties (treated with Obvious @ 4.6 oz / 100 lb seed and not treated seeds) were seeded at Williston Research Extension Center, Williston, ND on 2nd, 8th, 15th, 22nd, and 29th of May, and 5th and 11th of June 2020 using a 7 rows no-till plot planter.
Soil moisture and temperature data at 4 inches depth were recorded from May 5th to September 30th, 2020.
Unmanned aircraft systems equipped with multispectral, thermal, or RGB cameras were flown over the experimental field to assess canopy temperature (CT), normalized difference vegetation index (NDVI), and normalized difference Red Edge (NDRE.
At maturity, plant height was measured, biomass was collected from nine square feet, and the crop was harvested using a plot combine.

Preliminary results
2020 is an extremely drought year. We received annual precipitation of seven inches (from October 1st, 2019 to September 30th, 2020), which was half of the precipitation compared to an average of the last 63 years. This year, the first fall killing freeze occurred on September 8th, 2020, a month earlier than in 2019 (Fig. 1).
Averaged across other treatments, there was a significant effect of seeding date on plant height, yield, oil, and protein content, and a significant effect of variety on yield, oil, and protein content. An interaction effect of seeding date × variety was evident on grain yield and oil content. There was no effect of applied treatments on test weight, the average test weight across the treatments was 56.8 lb/bu. The effect of seed treatment was not evident on soybean growth, yield, and quality.
Averaged across variety and seed treatment, soybean seeded from May 2nd to 22nd, 2020 was about 18” tall. The plant height decreased drastically when seeding was delayed to May 29th or June 2020 (Fig. 2).
Averaged across seed treatment, when soybean was seeded from May 2nd to May 22nd, 17009GT and 18008GT yielded about 11.4 bu/ac and 10.1 bu/ac of grain, respectively. When seeding was delayed to May 29th, the yield of 17009GT decreased by 45% and that of 18008GT decreased by 24%. A further delay of seeding to June yielded no grain at all (Fig. 3). An early first fall freeze that occurred on September 8th killed all the plants and soybeans seeded in June could not produce grain.
Averaged across variety and seed treatment, soybean seeded from May 15th to 22nd had the highest grain protein content (~38%), which declined by 1 to 2.7% when the crop was seeded earlier or later in the month (Fig. 4). Averaged across other treatments, variety 17009GT had 1.8 % more grain protein content than the variety 18008GT (Fig. 5).
Averaged across seed treatment, 17009GT and 18008GT had about 22.85 % grain oil content when the crop was seeded from May 2nd to May 8th. When seeding was delayed, the oil content decreased by 0.64 to 1.75 % in 17009GT, and by 0.28 to 0.86 % in 18008GT (Fig. 6).

Works to be completed
We will be processing and analyzing the data on yield components from biomass, the data on growth and physiology from aerial images acquired with UAS, and the data on soil moisture and soil temperature collected with different sensors.

Acknowledgments
We acknowledge the financial support of the North Dakota Soybean Council. Mention of trademark or proprietary product does not constitute a guarantee or warranty of the product by North Dakota State University and does not imply its approval to the exclusion of other products which may also be suitable.

View uploaded report

Update:

View uploaded report

Determining suitable planting date and soil temperature for enhanced growth and yield of soybean under no-till semi-arid condition
(Executive summary – 2020/21)
Principal Investigator: Dr. Gautam Pradhan, NDSU Williston Research Extension Center
Co-Investigators: Dr. Jerald W. Bergman and Dr. James W. Staricka, NDSU WREC

Research Conducted
Two glyphosate tolerant varieties (‘ND17009GT’ and ‘ND18008GT’), either treated with fungicide Obvious @ 6.4 oz/100 lb seed or untreated, were planted at seven different dates (2nd, 8th, 15th, 22nd, and 29th of May, and 5th and 11th of June 2020) under no-till dryland conditions.

Why the research is important to ND soybean farmers
Soybean acreage has been steadily increasing in ND, including the western part of the state, which has an exceptionally drier climate (ppt: <15 in/year) than the eastern part (ppt: >20 in/year). There is a lack of soybean production management guidelines suitable for no-till dryland producers of western ND. The determination of suitable planting dates and soil temperature is crucial to avoid abiotic and biotic stress as well as to have a sustainable higher soybean yield and farm income under no-till dryland conditions.

Final findings of the research
2020 was an extreme drought year. We received annual precipitation of seven inches, which was half of the precipitation compared to an average of the last 63 years. Also, this year, the first fall killing freeze occurred on September 8th, a month earlier than in 2019, which killed all the plants planted in June.
The effect of planting date, variety, and seed treatment was not observed on grain number and test weight. Planting soybean on or later than May 29th significantly decreased plant height, above ground biomass, thousand grain weight, and grain yield. When soybean was planted on or before May 22nd, ND17009GT and ND18008GT yielded about 11.4 bu/ac and 10.1 bu/ac of grain, respectively. When the planting was delayed to May 29th, the yield of ND17009GT decreased by 45% and that of ND18008GT decreased by 24% (Figure 1). The variety ND17009GT, when averaged across other treatments, had higher biomass, grain weight, and yield than ND18008GT.

Benefits/Recommendations to North Dakota soybean farmers and industry
The results from this year showed that under no-till dryland conditions of western North Dakota, a season long drought may result in a massive decline in soybean yield (avg trial yield: 10 bu/ac in 2020, 30 bu/ac in 2019) irrespective of the date of planting. The study also showed that under drought conditions if planting is delayed to May 29th, soybean yield may become as low as 6 to 7 bu/ac; and if the combined effect of early fall killing freeze and drought occur, planting in June may result in zero economic yields.

Planting date plays a significant role in field crop production. Early or late planting may decrease grain yield and quality of a crop due to increased biotic (insect, disease, weed, and bird incidence), and/or abiotic stress (frost, drought, and high temperature). Western North Dakota has a cool semiarid climate with an annual precipitation of <13 inches, which is at least 5 inches lower than in the eastern part of the state. In addition, western ND (Williston) has a longer day length and higher evapotranspiration rate than in the southeastern (Fargo) part of the state during the growing season. Therefore, there is a need of determining optimal soybean planting dates and soil temperature for the western ND that provide optimum growing period, decrease chances of frost and/or drought damage, and enhance grain yield. The information on optimal planting dates and soil temperature from this research will ensure sustainable higher soybean yield under semi-arid no-till conditions and thus secure a more profitable future for western ND soy producers.