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Abstract.

Maintaining appropriate downforce throughout the field is critical for achieving uniform and consistent seed depth. Varying soil conditions, especially due to differences in soil properties (such as soil type, texture, moisture etc.) can produce differences in crop emergence and could affect yield significantly if not properly addressed. On-farm research trials were conducted at five locations across the southern portion of the State of Georgia to evaluate the effect of soil texture as measured by soil electrical conductivity (EC) on planter downforce while trying to maintain the desired seeding depth for planting cotton and peanuts. Soil EC was mapped to delineate EC zones within the field prior to planting. Trials consisted of planting test strips within the field at the nominal planter setup (metering unit, seed depth, seeding rate, downforce etc.) utilized by the grower across all soil EC zones in addition to two additional downforce settings (relatively lower and higher than nominal) with the similar planter setup. The downforce setting utilized by the grower to achieve the desired seeding depth was used as a reference to determine the two other downforce settings to be utilized as lower and higher settings than the reference downforce. The selected downforce values were dependent on the crop being grown (cotton and peanuts) and desired seeding depth. Post-emergence field data collection consisted of stand counts at 1 and 3 weeks after planting within each EC zone. Results indicated that crop emergence was affected by downforce. Optimizing planter downforce with varying soil EC levels could be beneficial as higher emergence rates were observed in the heavy textured (loamy clay) soils in the fields by utilizing higher than nominal downforce during planting. Contrarily, crop emergence was reduced in zones with sandy or sandy-loam soils by utilizing higher than required downforce. This study found that some growers could benefit from utilizing additional downforce than nominally used in heavy texture soils to maximize emergence as grower-selected downforce was unable to place seeds at the desired seeding depth causing reductions in emergence. In some cases, the nominal setup utilized by the grower performed equally well across the different EC regions within the field as indicated by high crop emergence in these regions. Relatively low emergence in one of the grower fields was attributed to the operator‘s inattention towards meter setup which resulted in poor planter performance in the field. This study also suggested that growers should be made more aware about their equipment setup and operation to use the available planting technology to its fullest, thereby maximizing planter performance in the field. The study emphasized the importance of quantifying soil properties, especially soil texture, within the field and optimizing planter settings based on changing soil properties for maximizing crop emergence.