Readers give their views on the pro’s and con’s of their fertiliser applicators
The why, when and how of applying fertiliser
Fertiliser is applied to maintain the health and appearance of the grass, it is also used to help pitches recover after a long period of play. As with all turf surfaces, different nutrient levels are applied at varying times of the year:-
• Spring/summer - more nitrogen is needed as the grass plants are actively growing
• Autumn/winter - more phosphate and potash is applied to encourage root growth.
The best condition for the application of fertilisers is when the immediate surface is dry, but with some moisture present in the soil. Dry, windy conditions are to be avoided, which may result in an uneven distribution followed by scorching of the sward. Fertiliser applications must always be followed by watering, in one form or another. Always check the calibration of the distribution machine prior to an application in order to determine the correct rate at which the fertiliser should be introduced, as detailed by the makers’ instructions.
A range of fertiliser distributors are used for spreading fertiliser evenly and efficiently. Distributors may be pedestrian-controlled or tractor-mounted. Any distributor should be able to carry out the following functions:
• Able to spread both granular and powdered fertiliser at a wide range of application rates
• The application rate should be easily adjustable
• It should be adaptable to sow grass seed on lawns and to apply top dressing
• It should be designed and built in a way that will reduce corrosion as far as possible.
This review considers two basic types of distributor: spinning disc and drop or conveyor belt.
Spinning disc spreader
Spinning disc distributors have a hopper in the shape of an inverted cone with an agitator at the base to prevent blocking. The fertiliser drops from the hopper onto a horizontally rotating disc driven by land wheels. This flings the fertiliser out in all directions.
The machine has a wide distribution width, so the job can be done relatively quickly.
A possible disadvantage is that less fertiliser falls at the edges of the distribution width than at the centre so giving uneven application. To compensate, plan runs so that they overlap. The distribution will also vary with any changes in forward speed.
Tips for calibration:
• Place a 1 m² sheet of corrugated cardboard on a surface
• Pass the distributor over it
• Collect up the fertiliser on the cardboard and weigh it
• Keep adjusting until your quantities are right.
Conveyor belt distributor
This type of spreader produces an even distribution and is generally used where a top quality finish is required. The machine consists of a hopper, the bottom of which takes the form of a rubber conveyor belt. The belt is driven by land wheels or gears and as it rotates it carries the fertiliser to the front of the hopper. The fertiliser falls out, through a gap between the base of the hopper and the belt, to the ground.
The application rate will not be affected by the forward speed as there is a direct link with the belt and the land wheel. Calibration can be carried out as for the spinning disc machine. The application rate can be adjusted by:
• Altering the distance between the bottom of the hopper and the belt; if widened, more fertiliser will pass through the gap and the application rate is increased
• Where a gear drive is used, the gear ratio can be changed to increase or decrease the speed of the belt in relation to the forward speed.
Case study 1
Stuart Wilson, Head Groundsman at St Paul’s Catholic School, Bucks
I use an EarthWay spinning disc applicator which is very versatile and is a strong piece of kit. It’s had a few knocks but it has not presented any problems as a result. The spinners are good and it copes well with the weight and the different types of fertiliser going through it. You have to spend some time on the calibration but when you’ve worked it out once, it’s very straightforward.
Spreading rates are set for you so it’s just a matter of opening up the spinners or putting your belt on faster or slower so you get a different width with the spread. It’s easy enough to achieve a decent, even spread.
The accuracy is good for fertiliser, which is essential, and I tend to use it wheel to wheel which prevents missing anything. Overlapping shouldn’t be a problem - I’d say this is down to the operator!
However if you do it when it is dewy you can see your wheel marks and get it really spot on. If you do it in normal conditions then it can be tougher to achieve.
I have had a bit of corrosion but that is probably down to the operator not cleaning it off properly and so there is a bit of rust. It can be difficult getting in some of the areas to clean but generally it is easy to maintain. So far there haven’t been any costs for maintenance, and storage is simple - it’s very compact.
Overall it’s a very easy to use piece of equipment. Once you’ve used it once you shouldn’t have any problems.
Case study 2
Ian Norman, Consultant & Industry Training, Norman Landscapes
The versatility of a drop spreader tends to be limited and is suitable to more regulated sizes, for example bowling greens and cricket squares. It is good where you run the risk of contamination of soft planting nearby which would be very susceptible to fertiliser scorch of the foliage resulting in plant damage and death.
Its durability depends on the make and the budgets available when purchasing. Most have a rubber conveyor belt to deliver the material which usually lasts quite a long time. More modern versions have brushes, which increases their durability.
The older designs are a nightmare to calibrate, to put it bluntly. It’s physically difficult on the older ones because the wheels are in the way. The more modern designs have a simple slide aperture on the rear of the machine.
The accuracy of distribution tends to be pretty high and I would say overlapping is down to the skill of the operator. You are more likely to get underlapping - because they drop to a very straight line, to match that is difficult and requires a very skilled operator.
The wheels are solid on the older models which will cause some problems but nowadays they are pneumatic so it’s less of a problem. On a damper surface that has some plasticity in it, there is a risk of marking, particularly on some designs.
Corrosion will occur if it is not maintained and this will be exacerbated if the machine is made of cheaper materials. As they are usually big they aren’t easy to store - you usually see them hung up on the back wall of a shed!