Dry (Granular) Fertilizer Spreaders
The accurate spreading of dry solid (granular) fertilizers can be done with handheld or push-behind fertilizer spreaders, which typically drop fertilizer through an opening(s) at the bottom of a storage hopper.
- Drop Spreaders. For drop spreaders (also known as gravity spreaders), the fertilizer drops through many evenly spaced openings across the bottom of the fertilizer hopper. Drop spreaders may also have a splash pan (baffle board) that helps to evenly distribute the fertilizer as it falls from the hopper openings to the ground, avoiding banding or streaking of the fertilizer. The swath (width of application) of drop spreaders can vary: push-behind types will range between 2.5 to 5 feet while tow-behind types are 4 feet or more. Drop spreaders can provide a very precise and accurate application of fertilizer. Narrow models are especially useful within small confined areas; for example, small courtyards and parkways between sidewalks and street curbs. Application overlaps and skips between side-by-sides passes of a drop spreader, however, can be challenging to operators, particularly for large turf areas requiring numerous passes (operator fatigue). Applying the fertilizer at half-rate in two directions will help to reduce the problem of overlaps and skips with a drop spreader.
- Rotary Spreaders. Rotary spreaders are also known as broadcast, cyclone, or centrifugal spreaders. Most rotary spreaders have a plate (impeller) below the hopper that spins as the wheels turn. Fertilizer drops from the hopper through adjustable openings and falls onto the rotating impeller, which throws the fertilizer away from the spreader in an arcing pattern. Applications with rotary spreaders are faster than drop spreaders because the material is broadcast over a wider area. Spreading width ranges from 6- to 60-feet depending on the model of rotary spreader being used. The speed that the spreader is pushed or driven has major effect on application rate. The edge of the fertilizer distribution is not as sharp with rotary spreaders and swaths of rotary spreaders should be overlapped (see manufacturer recommendations for specifics). Spreading of mixed fertilizers having particles of different size can also be a challenge with rotary spreaders because larger, heavier particles are thrown farther than smaller, lighter particles. As a result, applications with rotary spreaders are not as accurate and uniform as drop spreaders, but the distribution can be satisfactory if the proper overlap is used. Use of homogenous fertilizer products will also improve the distribution of an application.
Some rotary spreaders can be operated with a deflector shield, which will direct the applied material to one side of the rotary spreader. This setup on a rotary spreader is useful when applying fertilizer along features where fertilizer should not be applied; for example, the edge of waterbody or planting bed.
- Pendulum Spreaders. Pendulum spreaders have a spout that moves from side to side and can distribute fertilizes over relatively large distances when the spout moves rapidly. As with other spreaders, the application rate is controlled by openings at the bottom of the hopper and the speed that the spreader travels.
New Jersey law restricts the application of fertilizer within a buffer along a waterbody. Fertilizer application equipment should be operated to maintain minimum distance of non-fertilized turf away from the edge of a waterbody. The table below summarizes the minimum distances allowed based on the application equipment being used.
|Rotary Spreader (no deflector shield)
|Rotary Spreader with Deflector Shield
Liquid Fertilizer Application Equipment
Nutrients applied to turf in a liquid carrier (water) provide flexibility in nutrient placement: root zone or foliage.
Fertilizer can be sprayed on the turf in a liquid form using precisely controlled sprayer equipment. Fertilizer-water mixtures can be applied in 3 to 5 gallons of water per 1,000 square feet (130 to 220 gallons per acre) to ensure that the fertilizer is washed into the root zone (soil). Small amounts of nutrients applied directly to the foliage in low spray volumes (≤ 0.5 gallon per 1,000 square feet) are known as foliar feeding. Micronutrients and nitrogen, applied at sufficiently small rates, can be absorbed by the turfgrass leaves without burn.
Fertigation is the term used for the application of nutrients through an irrigation system. Very small amounts of fertilizer are metered into the irrigation lines and regularly distributed to the turf through the irrigation sprinklers. A well designed irrigation system capable of very uniform water distribution is needed for fertigation. The rate and amount of water applied must avoid surface runoff. Applications of very small amounts of nutrients have the advantages of more efficient plant uptake, more consistent plant growth rate, and labor savings. The adoption of fertigation for turf has been very limited and is primarily used on some golf courses.