Planting potatoes at a consistent depth is an important factor in achieving uniform crop emergence. Uniform emergence leads to improved crop input efficacy throughout the season and more consistent crop maturity at harvest. But, achieving consistent depth is often easier said than done: soil variation, areas of compaction, different moisture levels, and changing planter weight all make uniform seed placement challenging. Current planter technologies do a reasonable job in dealing with this challenge. However, new and creative ways of using non-planter technologies show exciting potential for improvement.
The least convenient technology for controlling planting depth requires that an operator make manual adjustments. Gauge wheels linked to spring-loaded furrow openers are more user-friendly but don’t suit every planter. Both methods produce good results in well-prepared seed beds with uniform soil conditions. However, efficacy drops in heavy and/or hard soil where gauge and planter wheels will tend to ride on top of the soil surface, and in dry, loose soil where wheels will sink in deeper.
A major and increasing challenge to improving planting depth consistency is the growing size and capacity of planters. Whereas four-row planters used to be the norm, producers now regularly use six-, eight- and even 12-row machines. In hilly conditions, it is more difficult to achieve consistent depth across wider planters. Planters’ hoppers and fertilizer/chemical storage tanks are becoming larger as the width of machine increases. The weight of a planter – especially a large capacity planter – beginning its first pass with a full load of seed and fertilizer (and occasionally other inputs too) is very different than the weight of that same planter as its load empties. This change can influence seeding depth substantially.
While some producers accept current technology’s limitations and learn to live with them, others are looking to new technologies to bring improvements and to add convenience. A few innovative growers have begun testing sonar sensors on their planters. Used more commonly on sprayer and harvester booms to ensure correct spray application height or potato drop height, sonar sensors installed on a planter can measure the distance to the ground many times per second and communicate with the planter’s hydraulic cylinders to adjust planting depth automatically.
On some planters, sonar sensors mounted on the front and rear are used to keep the planter level, thereby improving planting depth. On others, sensors are mounted to a tillage attachment on the planter to provide more consistent working depth. While raise/lower cylinders on many planters are connected to one valve, some producers are realizing that using separate valves for left and right cylinders in combination with sonar sensors provides a form of contour control in hilly fields. I think it’s incredibly exciting when a producer takes an existing technology, like a sonar sensor that was designed for harvest, and innovates to solve an entirely different challenge.