Yield response of soybean to planting date and row spacing in Illinois
Soybean [Glycine max (L.) Merrill] is a primary Illinois field crop, and maximizing returns through use of efficient soybean planting practices is important to producers. Recent studies of planting date and row spacing have been limited in geographic scope, and few of these have included both factors together. Studies combining these factors, and seeding rate, were conducted during 2010 and 2011 at six Illinois locations. Four planting dates and two row spacings were evaluated. Planting date had a large effect on yield and the northern locations experienced progressive yield loss with delayed planting. At the northern locations from April 19th to May 24th yield loss per day more than doubled from 10.9 to 24.9 kg/ha/day. At southern sites with poorer soils and more stressful environmental conditions, yield loss was not always progressively greater with planting delay. Across planting date at the eight northern sites narrow rows out yielded wide rows by 122 kg/ha (3.0%). A row spacing by environment interaction indicated that not all sites responded favorably to narrow rows. Another interaction between row spacing and planting showed that the narrow row yield advantage unexpectedly decreased with planting delay. Two the four southern sites also showed a yield increase from narrow rows. The data suggests that regardless of other factors, early planting and narrow rows increase yield. Planting date though clearly had the largest yield impact and planting earlier seems to present the greatest opportunity to maximize yield.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign