Starter Fertilizer

Effect of Planting Date and Starter Fertilizer on Soybean Grain Yield

Matthew W. Hankinson, Laura E. Lindsey, and Steven W. Culman

A trial was established at the Western Agricultural Research Station (WARS) in South Charleston, Ohio and at the Northwest Agricultural Research Station (NWARS) in Custar, Ohio to evaluate the effect of starter fertilizer on soybean grain yield across several soybean planting dates.

Quick Take-Away

  • Nitrogen (N) and phosphorus (P) starter fertilizer did not increase soybean grain yield. However, all three site-years had soil P levels greater than the critical level of 15 ppm (Bray P).
  • Soybeans planted on May 1 at the South Charleston, Ohio location yielded 94 bu/acre. Even at high yields, there was no yield response to starter N or P fertilizer.
  • Soybean yield decreased by 0.6 bu/acre/day when soybeans were planted after the first planting date at the South Charleston location in both years.
  • Timely planting is much more critical for maximizing soybean yield than use of starter fertilizer.

Methods. The trial was established in 2013 and 2014 at WARS and 2014 at NWARS. The soil series was Kokomo silty clay loam at WARS and Hoytville clay at NWARS. At all research locations, the previous crop was corn. The WARS location was minimally tilled in the fall, and the NWARS location was minimally tilled in the fall and spring. Soybeans were planted in 30-inch rows to facilitate starter fertilizer application. Soybeans, Asgrow 3231 (3.2 relative maturity), treated with Acceleron were planted at 145,000 seeds/acre.

Three to four planting dates were evaluated at each location ranging from May 1 through July 2 (Table 1). Starter fertilizer treatments were applied in a band 2 inches beside and 2 inches below the seed at planting. Starter fertilizer evaluated included:

  1. None (control)
  2. Urea at 30 lb N/acre
  3. Triple super phosphate (TSP) at 40 lb P2O5/acre
  4. Urea + TSP at 30 lb N/acre and 40 lb P2O5/acre
  5. Diammonium phosphate (DAP) at 40 lb P2O5/acre and 16 lb N/acre

Prior to planting, a soil sample was collected at 0 to 8 inch depth for nutrient analysis. Soil P (Bray P) was 33 ppm, 38 ppm, and 84 ppm at the WARS 2013, WARS 2014, and NWARS 2014 locations, respectively. Soil P was not limiting at any of the trial locations.

Table 1. Planting date and harvesting date for soybean at the Western Agricultural Research Station (WARS) and Northwest Agricultural Research Station (NWARS) in 2013 and 2014.
Location, year Planting date Soil temperature at planting from 2-inch depth (degrees F) Harvesting Date
WARS, 2013 May 1 59 Sept. 25
  May 20 68 Oct. 1
  June 12 73 Oct. 14
  July 2 73 Nov. 6
WARS. 2014 May 21 64 Oct. 2
  June 3 73 Nov. 3
  July 1 77 Nov. 3
NWARS, 2014 May 8 62 Sept. 25
  May 27 72 Oct. 27
  June 18 76 Oct. 27

Effect of Starter Fertilizer on Soybean Grain Yield. Starter fertilizer had no effect on soybean grain yield at any of the locations (Table 2). The soil P level at all three site-years was >15 ppm which is the established P critical level for Ohio (Vitosh et al., 1995). If the soil P levels were <15 ppm, a yield response to P starter fertilizer would have been much more likely to occur. In previously conducted studies, soybean yield response to N application in soybean was variable and generally occurred under high-yielding conditions when biological N fixation and soil residual N did no supply sufficient N to meet crop demand (Salvagiotti et al., 2008). Soil organic matter was 3.6 to 4.0% for the three site-years, which may have resulted in sufficient N mineralization to meet crop demand causing the lack of yield response to starter N fertilizer (Sawyer et al., 2006). At the WARS location in 2013, soybean yield was 94 bu/acre when planted on May 1; however, starter N fertilizer did not increase soybean yield, indicating that biological N fixation and soil residual N were adequate.

Table 2. Starter fertilizer did not significantly affect soybean grain yield at all three site-years (90% confidence).
Location, year Fertilizer treatment Grain Yield (bu/acre)
WARS, 2013 None 73.6 A
  Urea 76.1 A
  TSP 77.2 A
  Urea + TSP 74.8 A
  DAP 77.2 A
WARS, 2014 None 58.0 a
  Urea 59.5 A
  TSP 60.1 A
  Urea + TSP 61.8 A
  DAP 62.1 A
NWARS, 2014 None 54.0 A
  Urea 53.9 A
  TSP 53.8 A
  Urea + TSP 53.8 A
  DAP 53.9 A

 

Effect of Planting Date on Soybean Grain Yield. Soybean grain yield was influenced by planting date at the WARS location, but not the NWARS location. Soybean grain yield decreased by 0.6 bu/acre/day at the WARS location both years when soybeans were planted after the first planting date (Figure 1). Soybean grain yield was not affected by planting date at the NWARS location.

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References

Salvagiotti, F., K.G. Cassman, J.E. Specht, D.T. Walters, A. Weiss, and A. Dobermann. 2008. Nitrogen uptake, fixation, and response to fertilizer N in soybeans: A review. Field Crops Res. 108:1-13. doi:10.1016/j.fcr.2008.03.001

Sawyer, J., E. Nafziger, G. Randall, L. Bundy, G. Rehm, and B. Joern. 2006. Concepts and rationale for regional nitrogen rate guidelines for corn. Ext. Bull. PM 2015. Iowa State Univ., Ames.

Vitosh, M.L., J.W. Johnson, and D.B. Mengel. 1995. Tri-state fertilizer recommendations for corn, soybeans, wheat, and alfalfa. Bull. E-2567. Ohio State Univ. Ext. Serv., Columbus.

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Acknowledgements:

  • Research funded by Ohio Soybean Council.
  • Seed donated by Monsanto and TSP donated by the J.R. Simplot Company.
  • Thanks to OARDC staff for field assistance.

 

 

Originally published:  Hankinson, M.W., L.E. Lindsey, and S.W. Culman. 2015. Effect of planting date and starter fertilizer on soybean grain yield. Crop, Forage, and Turfgrass Management. doi:10.2134/cftm2015.0178.