Corn planters are horizontal devices attached to a tractor that automatically cut trenches, drop in kernels of corn, and cover the seed with soil. The machines use a disc or drum that opens to release the seed, with a hydraulic blower to move each kernel. Some come equipped with seed sensors capable of controlling the spacing of each seed to help ensure proper growth. When seed placement is controlled, it can produce higher yields for the farmer.
Various models and sizes of corn planters are available, depending on the farmer’s needs and how much he or she can afford for equipment. Most corn planters can handle between 12 and 30 rows in one sweep across a field. Typically, this equipment includes tanks that hold fertilizer, with the larger units capable of carrying several tons of liquid and enough corn to cover more than 100 acres before refilling is necessary. The farmer controls the speed of the planting process according to the corn planter's efficiency, which is usually between 4 and 8 miles (6.4 and 12.9 km) per hour.
The largest corn planter spans almost the size of a traditional football field. These machines can cover more acres per day and are outfitted with a global positioning system to regulate precise planting criteria. Corn planters commonly fold up so they can be transported from barn to field and need less storage space. They attach to the tractor with a ball and hitch.
George W. Brown invented the first corn planter from a cultivator in the 1850s that eliminated the need for a farmer to bend over while planting. These early models were constructed of wood, which ended the need for the farmer to tote a bag of corn slung over his shoulder. The patented corn planter used a trigger mechanism to release a kernel of corn into a hole the farmer made with a stick. It wasn’t long before the equipment was modified with two hoppers that planted two seeds at once.
A critical component to successful farming with a corn planter is maintenance of the equipment. If spacing of the seeds is too close, the plant might wither from lack of sunlight. When kernels repeatedly fail to release from the drum, it can substantially reduce the crop yield. Depth control is also important to allow the corn to sprout, especially when planting in untilled ground.