Compost Application Guide for Professional Turf(Click to expand).
Why use compost?
Compost has a wide range of soil and plant health benefits that lead to a functioning soil and healthy, robust plants. Compost used in turf applications has lead to decreased water, fertiliser and humate use. Compost reduces the incidence of disease, and suppresses sting nematodes in the soil. Using compost leads to a healthy soil and plant system that requires fewer interventions, fewer inputs, and fewer dollars. Of course you might want to make the transition to using compost, but the application methods are different to most other inputs, so here we present some reliable methods for using compost in turf applications.
In order to get the best results from compost, some preparation is the ideal. This can be done using conventional turf equipment and methods, it’s just a question of timing.
Step one is to vertimow. Removing some of the thatch allows easier penetration of the compost into the thatch and gets it in contact with the soil. Applying compost directly to the surface without penetration it will still work, but vertimowing increases the efficiency of the application.
Hollow or solid tyne coring
Step two in the ideal preparation is soil coring. Tynes of approximately 20mm are best, with or without hollow cores. Coring is worth doing for its own sake, but the idea in this case is to provide a pathway for compost to enter the soil. Compost will work from the surface, but it is most effective when some of it is within the soil profile. Some form of dragging will need to be used to push compost into the holes. 20mm tynes are required so that the holes are big enough to get fine compost to fit down them easily. The type of tyne is best decided by you according to which type will leave an open hole in your soil.
A mowing can be used at this point to pick up/break up the cores. This is mainly to give you a smooth surface. It isn’t required for compost applications as such, so do as you would normally do.
After coring and mowing the turf should be given water and allowed to grow leaf 10-20mm longer than usual. This is to allow for leaves to be long enough to stick up above the compost after it has been applied to the surface. If the grass is completely shaded by the compost it will yellow and be set back, but by allowing longer leaf to grow the grass can still get sunlight in the period immediately after compost application.
Before spreading compost, large and deep holes in the turf surface should be filled with sand, preferably by hand. Holes should be filled to match the surrounding soil surface, not to the level of the thatch. For situations where there is widespread surface unevenness C-Wise can supply blends with sand that can be used for levelling by dragging.
If you’re lucky enough to be at the establishment stage, the best thing you can do is to put compost down as an underlay. To do this prepare and level the soil as you would normally. Apply a 10-20mm layer of compost to the surface, and then lay turf rolls directly onto the compost. If runner are to be used, compost needs to be blended into the soil to a depth of 100mm. This can also be done when using rolls, but isn't as necessary.
Topdressing - Rates
Compost can be applied to the turf surface at rates between 20-200m3 (2-20mm thickness), but our recommended maximum rate is no more than 150m3.
This is how a maximum rate application should look. Depending on grass type and health, a finish like this will range from 100-150m3 per hectare (10-15mm thick). Tall and leafy thatch will hold more compost than compacted thatch with short leaves. It is critical to avoid covering too great a proportion of leaf. Too much coverage will lead to yellowing and poor plant vigour in the short term. This is as a result of compost physically blocking light, rather than negative effects of compost itself. After the compost has settled into the thatch you can lower the turf height again. Alternatively you can keep it short, but only put on light applications of compost. If you need a greater amount you can do several applications over time.
This is a rugby pitch freshly spread with 100m3 of compost. Only a few larger particles are visible. These will mostly disappear from easy sight after watering, and the rest after mowing.
Below is what happens with a massive over application of compost.
This is turf 5 weeks after being covered with 50mm (500m3 per hectare) of compost. There was no leaf visible when the compost was applied, and now there is approximately 50 percent coverage. The turf has recovered remarkably, but now faces a long period of infill and recovery. This amount of compost is far outside the recommended levels, and can have negative water and nutrient effects at this level, just as a massive over application of fertiliser or water would.
Most contractors will use a belt and spinning wheel spreader. This allows them to spread large areas quickly and neatly.
This method has low impact on the turf surface and usually requires only one pass. Using a spreader of this type allows for applying compost to areas in the hectares range.
The belt moves slowly backwards carrying compost out of the spreader and drops it onto spinning wheels with paddles that spread the compost evenly. This particular spreader is high quality. It is very easy on the product, with a good paddle design and a slow spinner speed. This results in an even spread and no dust from our products.
This is the same product as above being spread by an older spreader with a different spinner design that is harder on the material. The spreader is PTO driven, so speed is regulated by engine revs. The tractor (approx 100 horsepower) in this picture is being operated at the normal revs for PTO implements, but the spinners are running very fast. This results in a lot of dust through the material getting pulverised and thrown too far in the air at too high a speed. High impact from the paddle breaks the product down, and then being ejected at high speed results in the fine particles being separated by wind resistance and left to hang in the air without heavier particles to drag them down.
The tractor doesn't need to be running at full revs, the power requirement for pulling and running this sort of spreader is low. Dust can be reduced by reducing the revs by a third and going up a gear to maintain ground speed. This reduces the spinner speed and eliminates most of the dust. Going down to half speed could reduce the dust almost to zero, but may narrow the spreading width. Dust can be further reduced by increasing the rate of material coming out of the hopper, meaning more material on each paddle, so less impact per unit of material. Ground speed would need to be increased to maintain the same application thickness in this situation. This being said, the dust shown in the above picture is not going to be an issue. C-Wise closely monitors water content to make sure that the product goes out in the correct state. Ensure that any supplier you use knows what the water content of their product at the current time. Stockpiling in summer can lead to products drying.
There are other spreading methods, but belt and spinner spreaders are the most efficient and gives the best results
For small area applications a skidsteer loader (bobcat) can be used. This method wouldn't be recommended for spreading an entire oval, but is relevant where an area is too large to do by hand and too small to justify bringing in a contractor. Ideally the operator would pick up buckets from an area off the main turf area, and then trickle out compost from the bucket while travelling. If the application rate is right, a single backblade will push the compost into the thatch and lift the leaves above most of the compost.
Spreading compost by trickling while travelling forwards, either by tilting the bucket or using the 4 in 1 function.
Backblading should be done with a steep bucket angle. A shallow bucket angle while backblading is good practice in construction, but when spreading compost it leads to smearing.
A steep bucket angle pushes compost into thatch and causes leaves to spring up afterwards.
Backblading with a shallow bucket angle leads to smearing of compost. This gives an unattractive appearance and shades a significant amount of leaf.
Avoid dumping piles of compost and then spreading by backblading. The areas near to the pile will have very high applications rates beyond what is desirable.
The resulting coverage close to the pile will leave very little leaf showing through. This will reduce the plant's photosynthetic capacity, and will lead to yellowing and poor growth. Coverage can be reduced by multiple passes, but it can take 10 or more passes near to a spreading pile before enough leaf shows through. This risks damage to the plant, and uses a lot of machine time.
For small areas or patching of holes, compost can be hand spread. Spreading by casting from a shovel produces similar results to a belt spreader, but will be less even. Deep holes should be filled with sand and levelled. As with other spreading methods the aim is to minimise the amount of leaf that is shaded by compost.
After compost application use a drag mat or frame to level and push compost into thatch. After this the turf should be given a longer than normal watering. The impact of the water works compost into the thatch and allows leaves to spring up around it. One to two weeks after compost application it is time to mow with a rotary mower. This breaks up any of the bigger compost particles still left sitting on the top of the thatch, and the lighter machine avoids leaving ruts in the ground, which will be soft at this stage. After another two weeks heavier cylinder mowers can be used again.
Repair can be done using any of the methods above. For large bare areas (above 1m2) fresh turf rolls can be applied either before or after compost spreading, but underlays are the best option. Belt spreading or hand spreading can be done after repair, but spreading using a skid steer should be done before applying new turf. Spreading compost can be sufficient to repair turf that is damaged but doesn’t have large bare areas. The ability of compost application to allow turf to repair is usually greater than you might expect. Recovery of full surface cover is just a matter of time unless there are serious underlying issues. Using fresh turf to cover holes is mostly a way to reduce recovery time. After starting to use compost some sports field managers have gone from using several hundred meters of turf rolls for repair per sporting season down to ordering one pallet just in case.
For any further questions or clarification please contact us
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