Conversely, if soil test levels are medium or higher, benefit from deep placement may increase yields. Conversely, if soil test levels are medium or higher, benefit from deep placement is unlikely. Deep-banded fertilize becomes more effective than surface applications as tillage intensity decreases when residual soil test levels are low. Application Equipment for P and K Conventional equipment can be used for broadcast applications. Dry P and K can be applied below surface by gravity from planter fertilizer boxes, or by pneumatics from a trailer behind a planter or tool bar.
Liquid usually is applied using squeeze pumps with a tube to each row.
Farmers are familiar with double disk openers because many planters use them to open the seed slot. As the disks open the slot, a tube drops liquid or dry fertilizer into it. Full rate application can be made with this placement. A disadvantage of disk openers is that they can be hard to hold in the ground, and may tend to ride over heavy residue. Another type of deep placement device is the coulter and knife.