oybean acreage has dramatically expanded westward and
During 1999-2001, the experiment was conducted at Carrington, Minot, and Hettinger to study the performance of two varieties (Traill – maturity group 0.0 and Daksoy – maturity group 00.5) tested at three row spacings (6-7, 18-21, and 30 inch) and three planting rates (100,000, 150,000, and 200,000 pure live seeds (pls)/A). In addition, normal (18-21 May) and late (early June) planting dates were investigated at Carrington, and no-till compared to minimum-till systems were compared at Minot and Hettinger.
Averaged across the three years of the trial, solid-seeding increased seed yield 10% and 18- to 21-inch rows increased yield 5% compared to 30-inch rows. Planting 200,000 pls/A resulted in an average stand (4 site-years) of about 144,000 plants/A. The high- and mid-planting rates produced 15% and 6% higher average yields, respectively, compared to the lowest planting rate. In years with above-average August rainfall at Carrington (1999 and 2000), yield increased as seeding rate increased and as row spacing decreased. Under conditions of slightly below-average precipitation during podfill (2001), yield was unaffected by seeding rate or row spacing. The normal planting date provided a 6% seed yield advantage vs. late planting. No-till improved yield 24% compared to minimum till across years in the western locations.
During 2002-04, the experiment was refined and conducted at Carrington and Minot (2002 only) to study the performance of two varieties in 6- to 7- and 12- to 14-inch rows and planting rates of 175,000 and 225,000 pls/A. The varieties included Walsh (maturity group 0.0) and Barnes (maturity group 0.3) or RG200RR (maturity group 0.5). In addition, first-half vs. last-half of May planting dates were investigated at Carrington.
Solid-seeding increased seed yield in 2 of 4 site-years
(Carrington and Minot, 2002) with a 4 site-year average of 36.3 bu/A with the 6- to 7-inch rows compared to 34.6 bu/A with the 12- to 14-inch rows. At Carrington in 2004,
14-inch rows yielded 22.2 bu/A vs. 7-inch rows at
19.8 bu/A. The three-year average stand at Carrington
was 151,700 plants/A with the 225,000 pls/A planting
rate and 131,700 plants/A with 175,000 pls/A. Yield
was similar between planting rates in 3 of 4 site-years (Carrington, 2002-04),
with a 4 site-year average of 36.2 bu/A with the
higher planting rate vs. 34.6 bu/A with the lower
Based on an initial yield potential of 25 bu/A and experiment results, if a soybean grower plants on a timely basis (6% yield increase vs. late planting), using narrow rows (5-10% yield increase vs. 30-inch rows), and establishes an adequate plant population (6-15% yield increase with > 140,000 plants/A vs. < 120,000 plants/A), a yield increase of 4-8 bu/A is possible. Using a soybean market price of $5/bu times 4-8 bu/A equals a gain of $20-40/A if a grower has a similar yield response with planting strategies as generated by the trial. In addition, improvement in income can be anticipated with direct-seeded systems.