Types of application equipment
There are two broad types of ground based spreading equipment:
- Broadcast equipment that spreads fertiliser beyond the width of the machine (including single, twin disc and oscillating spout spreaders)
- Placement equipment where the swath width is equal to or less than the width of the machine (including band spreaders, side-dressers, planters with fertiliser application).
Broadcast equipment
Broadcast equipment spreads fertiliser by throwing particles sideways. The discharge rate, shape and density of the particles, the throw speed, wind speed and direction, and land topography all influence the pattern achieved.
Single disc spreaders
Smaller or older spreaders may use a single spinning disc to throw fertiliser particles sideways. The size and rotational speed of the disc determines the speed of pellets or particles as they leave the disc, so contribute to spread distance. By shaping the disc and using different vanes, the application pattern can be adjusted. Many single disc machines spread unevenly, with a greater amount of fertiliser being applied on one side than the other.
Twin disc spreaders
Many newer machines use twin discs that rotate in opposite directions. This improves uniformity and may increase spread distance. Some equipment allows the speed or settings of one disc to be adjusted to concentrate fertiliser application in a narrower band for headland application.
Oscillating spout spreaders
Oscillating spout machines fling fertiliser from a tube shaking rapidly from side to side. The length, speed and design of the spout control fertiliser placement. By changing spouts and speeds, even, banded or single side fertiliser applications are possible.
Placement Equipment
Placement equipment does not rely on particles flying through the air. The width of application is no more than the width of the machine, with a range of metering devices used to control the amount of fertiliser being applied, typically in bands. If applying in bands to individual rows, each row should apply at the same rate for correct plant nutrition.
Drills and planters
Many drills and planters have ability to apply fertiliser at the time of seed sowing. They differ in how the fertiliser is distributed to individual coulters but generally meter flow into drop-tubes and place bands of fertiliser along planter rows. The picture below left shows a seed drill with a fertiliser hopper. Fertiliser drops into metering devices and the controlled flow is directed down drop-tubes to coulters at the rear of the machine. Each should deliver at the same rate. The picture below right shows a precision planter and trailing fertiliser cart. Fertiliser in the cart is air blown forward to individual planter units for direct placement beside the seed.
Side-dressers
Side dressers are used to apply fertiliser to growing crops such as maize or sweetcorn. The machine shown in the picture below has metering devices below the hopper that direct controlled rates of fertiliser into tubes. Air is used to carry the measured fertiliser to drop-tubes along the tool bar, allowing bands of fertiliser to placed along individual planted rows. At the same time, mechanical weeding is taking place.
