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Executive summary:
Impact of selected establishment factors on soybean production
Greg Endres, Extension area agronomist (principal investigator), and Dr. Mike Ostlie, NDSU Carrington Research Extension Center (CREC) research agronomist
Field study 1 was initiated in 2011 and concluded in 2016 at the CREC to examine soybean response to early planting and P (phosphorus) fertilizer application methods.
Seed yield was similar with 2016 trial planting dates of May 5 and May 18. This was likely due to hail damage that occurred on July 9 and having adequate soil moisture during crop reproductive stages. Averaged across 4 site-years of this study, early planted soybean (April 30 to May 5) had a 2.0 bu/acre (4%) advantage compared to a normal planting period (May 15-23). While risks exist for planting soybean early, increased yield potential exists without additional expenses.
Broadcast (either preplant incorporated or pre-emergence surface applied) P fertilizer (liquid 6-24-6) applied at the NDSU recommended rate based on soil analysis and yield goal, to a loam soil testing low to medium for P was compared to P application in a 0x2-inch band (two-third rate of broadcast) during planting. Averaged across 5 site-years (2011-14, 2016) of this study, indicates a 1% yield increase with broadcast versus banded P. The modest yield increase with broadcast versus banded P fertilizer will have to be considered by farmers as they review their plant nutrition strategies for soybean production.
Field study 2 was initiated in 2015 and continued in 2016 at the CREC to examine soybean response to paired rows and plant canopy types. The newest interest with soybean row spacing is with paired rows, but research data is limited in North Dakota. As farmers consider row spacing options, they also ask about the best choice of plant canopy type when determining soybean varieties to grow. Data from this study will assist in answering questions regarding any advantages with using paired-row spacing and if plant canopy type is a contributing factor to increasing soybean yield.
In 2016, row spacing includes: a) 7-inch pairs (centered on 28-inch spacing), b) 14 inches, and c) 28 inches; and plant canopy types include: a) intermediate (Peterson Farms Seed 12R05) and b) bushy (PFS 15R05N). The varieties have the same maturity group rating; and have similar yield potential, plant height and several other agronomic traits.
Averaged across the two varieties, early and late season plant stand was similar among row spacings (early season trial average = 132,600 plants/A). Seed yield was similar between paired (50.7 bu/A) and 14-inch (52.5 bu/A) rows, and greater than 28-inch (44.6 bu/A) rows. Averaged across row spacings, canopy types had similar canopy closure (measured Aug. 15) and yield. Plant response, and seed yield and quality with the row by plant type interaction were not statistically significant. No conclusions will be made with the two factors or interactions until the study is tentatively completed in 2017.