Soybean Planting Date Experiment
J.A. Torrion, Ze Fang, Amanda Shine
To examine the planting date effect on yield and agronomic performance for soybean cultivars in Northwestern Montana
This experiment utilized a split-plot design with planting date as the main block and varieties (maturity group) as subplots replicated three times. The three planting dates (PD) were 5/15, 5/29 and 6/12. The five relative maturity groups (MG) were 002, 005, 006, and 008. Harvest time was determined by observation when all the pods turned brown (i.e., 10/1 for PD 5/15 and 10/10 for the other two PDs).
Inoculant was inadvertently omitted during the seed preparation, so urea was added as rescue nitrogen (N). To minimize N loss of the applied urea, irrigation was applied immediately after urea broadcast. Table 1 is the detailed management information.
All MG (002-008) yielded similarly with planting date. The yield of PD May 15 averaged 28.8 bu/A. Delaying PD decreased yield. The PD May 29 yielded, on average, only 16.0 bu/A, and the latest PD (June 12) had near zero yield (Figure 1). This experiment was planted with 30-inch row spacing and narrower rows will be tried in 2019 with wider MG and PD ranges.
Table 1. Management information
|Seeding date:||May 15, May 29, June 12||Harvest date:||October 1, October 10|
|Julian date:||135, 150, 166||Julian date:||274, 283|
|Seeding rate:||About 115,000 plants/A||Soil nutrient residual (lbs/A):||93-7-84 (Fall, 2017)|
|Previous crop:||Spring wheat||Nutrient fertilizer applied (lbs/A):||120-50-0|
|Tillage:||conventional||Fungicide:||Priaxor (at begin pod stage – R3)|
|Soil type:||Silt loam||Seed treatment:||Cruiser 5FS, Apron Maxx RTA|
Average yield of soybean varieties in 2018 with respective planting dates May 15, May 29, and June 12 planted on silt-loam soil.