Determining the Optimum Planter Downforce Settings in Soybean.

Planter technologies such as downforce could assist with maintaining uniform seeding depth while planting, affecting crop emergence, yield, and producer economics. Previous research exists evaluating planter technologies and emergence in corn (Zea mays L.) where up to 10% yield increase has been observed with uniform stands. Planter downforce can influence agronomic factors such as uniform seeding depth, sidewall compaction, seed furrow creation, and seed to soil contact. In South Carolina, soybean (Glycine max L. Merr.) is grown among varying soil textures, topography, and tillage practices, therefore, planter downforce may have a benefit in establishing uniform emergence. This research was conducted at the Edisto REC near Blackville, SC and at the Simpson REC near Pendleton, SC. Four-row plots were arranged within a split-split plot experimental design, where tillage (conventional/strip-till – EREC and conventional/no-till - SREC) was the main plot factor, gauge wheel (normal and narrow) was the sub-plot factor, and downforce (target gauge wheel load) was the sub-sub-plot factor. Five different downforce settings (0 to 136 kg) were applied to soybean planted in each tillage system at each location. A 4-row John Deere 1700 planter with Precision Planting DeltaForce on 76-cm row spacing was utilized for planting of all treatments. Tillage type and gauge wheel setup influenced emergence counts at 1 and 3 days after emergence (DAE) at Edisto and 3 DAE at Simpson. Downforce rate had an effect on plant emergence 4 DAE at Simpson where rates over 68 kg had greater emergence than 0 or 23 kg. Yield data has been collected, however, results have yet to be analyzed. Continued research on the impacts of planter downforce on the agronomic and economic factors in soybean production in South Carolina is needed.