High‐Yield‐System‐in‐Place (HYSIP) Concept for Soybean Production

Although the yield advantage of solid‐seeding and semidwarf soybean [Glycine max (L.) Merr.] cultivars is well documented, late season drought or other yield limiting factors can minimize, or eliminate, the potential yield advantage of these production factors. This lack of consistent yield response has been a barrier to grower acceptance of these new production systems. The purpose of this research was to determine the frequency, magnitude, and long‐term average yield advantage of a typical solid‐seeded‐semidwarf (SSS) system over a typical wide‐row‐indeterminate (WRI) system over a period of 10 yr on two diverse soil types in Ohio. ‘Williams’, an indeterminate cultivar widely grown in the Midwest, and ‘Sprite’, a determinate semidwarf cultivar developed specifically for it's adaptation to high yield environments, were compared in 30‐ and 7‐in. row widths. The SSS system yielded 23 to 24% (12–14 bu/acre) more than the WRI system averaged over the 10 yr. The SSS system exceeded the yield of the WRI system in 7 out of the 10 yr, with the yield advantage ranging from 9.7 bu/acre (15.6%) to 32.0 bu/acre (61.4%) on the more drought‐prone Hoytville silty clay loam soil (fine, illitic, mesic Mollic Ochraqualfs) at Hoytville, OH. At the South Charleston location, on a Kokomo silt loam soil (fine, mixed Typic Agriaquolls) less prone to drought stress because of excellent water‐holding capacity, the SSS system out‐yielded the WRI system 9 out of the 10 yr, ranging in yield advantage from 8.7 bu/acre (13.9%) to 31.6 bu/acre (61.2%). The greatest yield advantages at both locations were associated with high August rainfall. In the three dry years at Hoytville, yields of the SSS system were equal, or nearly equal, to the WRI system, demonstrating how late season drought can prevent the expression of the higher yield potential of the SSS system. The year there was no yield increase was from the SSS system at South Charleston was associated with severe foliar disease infestation. Based on these data, a high‐yield‐system‐in‐place (HYSIP) concept was developed for soybean production. Simply stated, a grower needs to have a high‐yield‐system‐in‐place every year—even though it is known that in some dry years there may be no yield advantage—in order to take advantage of the favorable moisture years to produce long‐term higher average yields. These data indicate that on many Midwest soils, where soybeans are currently planted in 30‐in. rows, soybean growers could increase their long‐term average yields by applying the HYSIP concept to the SSS system. Switching to narrow rows alone would also significantly increase yields. Basing a decision not to switch to narrow rows or semidwarf cultivars on the non‐response data obtained from occasional dry years could be a costly decision for Midwest growers and farm managers.