Joof Alberts has embarked on a process of spreading mulch under the trees on his farm to assist with increasing production, increasing soil water holding capacity, tree health, minimising erosion and covering exposed roots.
Joof has decided to apply a thick layer of mulch (approx 75mm thick) and do a section of the farm each year. The idea being that a thick layer of mulch will last longer and provide greater benefit to his trees, compared to applying a little “sprinkle” to all trees each year, which is hardly noticeable.
Joof has applied approx 60t/ha of mulch per hectare. The material has been sourced from the Ballina Waste Management Centre. This material was chipped at the waste centre using a tub grinder, with 2 grindings being done 6 weeks apart. This double grinding process produces a finer chip, which is better suited to macadamia orchards (as it has less pieces of material that can be picked up in a harvester).
The material was spread by Bill Johnson of Precision Mulch Spreading. The machine Bill uses allowed him to control the rate of application to achieve the heavier application level that Joof wanted.
The total cost was $38.45 per tonne. This includes the mulch, transport and spreading. As there is approximately 2m3 per tonne, the cost is $19.23/m3. Joof believes that this cost can be brought down by improving what he did, such as increasing the efficiency of transport.
Benefits from the mulch application
There are many benefits from spreading mulch or compost, and some of the most notable ones that Joof has observed are:
- In the areas where he spread the mulch there are no more exposed roots. This has improved the tree health and created a surface that in time will make harvesting easier.
- Erosion stopped – with all the rainfall experienced, Joof hasn’t seen any erosion in the areas where he applied the mulch.
- There is new fine feeder root growth occurring in the mulch. With all of the rainfall, this has the potential to reduce the effects of phytophthora on the trees.
There are many other benefits that have been found from applying heavy levels of organic mulch or compost, which have not been discussed here. These include reducing phytophthora disease incidence and improving nutrient cycling.
Harvesting from the mulch
The mulch was laid in November 2010 and the first harvest rounds have just been completed off the mulch. Joof has found that the material has settled down well, and the finger wheel harvester has been able to pick off it well. There is a slight depression where the outside wheel travels, but this is not impacting upon harvesting. In time, Joof believes the application of this mulch will pay tremendous dividends, creating a surface that the nuts will sit up on (rather than being trapped in between roots) and lower his erosion risk.