Fertilizer Knives

The invention of fertilizer knives gave farmers the ability to apply fertilizers of all types below the surface of the soil. These agricultural knives cut grooves to whatever depth is preferred for fertilizing a particular crop. The knives mount to a toolbar, coulter or other equipment made for cultivating or seeding. Most fertilizer knives bolt into place. Some include an extension arm or adapter.

Each knife has one or two attached tubes, usually made of rubber or steel, to which the farmer can connect fertilizer hoses. Pneumatic pressure often is used to push the fertilizer from the fertilizer tank through the hoses and into the ground. The rate of application can be set by adjusting pressure.

For small plots, farmers sometimes use squeeze pumps instead of pneumatic pressure to send liquid fertilizer through the tubes attached to the fertilizer knives. Occasionally, belt cones are used to move granular fertilizer through the tubes. Dry fertilizers also may be distributed from auger-style fertilizer boxes through fertilizer knife tubes into the soil at depths chosen by the operator.

How to Select the Right Fertilizer Knife

Before deciding what type of fertilizer knife will work best, determine whether to use gaseous, liquified or granular fertilizer to nourish your crops. Individual components of your fertilizing system will vary according to fertilizer type. One difference will be the diameter of the hoses and the tubes they attach to that are mounted on the fertilizer knives.

Consider the type and condition of the soil where the fertilizer knives will be used. The shape of the knife determines the type of cut that it makes. If you are planting and fertilizing in previously undisturbed soil where the climate is quite dry, you want fertilizer knives that disturb as little of the soil cover as possible so that moisture is held. Fertilizer knives that make a sharp, clean cut and are shaped to immediately return the dirt to cover the cut once the fertilizer is released work well under such conditions.

If you want to fertilize at the same time that you plant, you need a system with knives that provide for the fertilizer to be distributed a bit to the side of the seeds and slightly deeper in the soil. One common practice is to distribute fertilizer two inches to the side and two inches deeper than the seed. Some systems use a wide wheel that trails behind the seed and fertilizer knives to automatically close the trenches.

Think about the wear and deterioration that occurs regarding the fertilizer tubes that are attached to, or mounted on, the knives. Common choices in tubes are rubber, carbon steel and stainless steel. Differences exist in how the ends of the tubes are shaped and the wear they sustain. Look for designs that provide tube protection and minimize plugging.

Because fertilizer knives are exposed to difficult conditions including weather, chemicals and surface obstacles, you may want to compare costs of purchasing and replacing throwaway knives with investing in knives that use replaceable tips or toes. Fertilizer knives are made of varying strengths and durability. Some are hard surfaced at wear points. Wear surfaces of cast chrome alloy, carbide or boron steel take more abuse than those made solely of carbon steel.

Expert Advice a Phone Call Away

If you have questions or would like to know more, call Wearparts LLC at 1-888-4-BLADES or visit our web site at wearpartsllc.com. Our knowledgeable staff can guide you to the right fertilizer knife for your needs. We offer a full range of tillage tools including disc blades, coulter blades, ADU unit parts and more!

Wearparts LLC boron steel gives our knives the toughness they need to cut through packed soils. These knives hold their shape, keep an edge and last longer than those made of conventional steel. Our knives fit agricultural equipment built by several major manufacturers, and we can adapt them to fit customized designs.