A mature olive tree at about 10 years of age should stand around 3 to 4 meters high and give a yield of around 40kg per year.
The tree should bear for at least 100 years, but many areas of the world experience “alternate bearing” years with a good crop one year and a poor crop the next.
Planted at a spacing of around 5m x 8m, a hectare (2.2 acres) would support 250 trees, which should (!) give you 10,000kg (ten tonnes!) of olives a year.
At $1 per kilo, that is an income of $10,000 a year, but that will involve quite a bit of work and time.
The spacing at 5 x 8 is traditional, but may not be ideal for all applications.
There are some very effective groves planted at 5 x 5, and the new theory of over-the-row straddle harvesting seems to work well with 3 x 7m spacings.
How much will it cost?
To prepare a block of land to plant 250 trees, as above:
- Drainage test - you can do it yourself digging holes or a backhoe/posthole digger
- Soil test - worth doing a couple, allow $300 to $500
- Soil improvement - lime, gypsum, ripping using a contractor, discing, etc …. allow $1000
- Trees - from a wholesale nursery, about $7 each for young trees x 250 …. around $3500
- Planting costs - including stakes, protection from hares and roos, fertiliser, etc (but not labour) … around $1000
- Irrigation - pump, filters, pipes, drippers, risers or sprays …. around $4000
All up, allow $10,000 per hectare to be on the safe side ($40 per tree is what I usually quote), assuming you will do much of the work yourself. Don’t forget, somebody has to cut the grass, pull out the weeds, spray the bugs, tie the trees back up after the storms, prune them into shape and you will not get a crop until the tree is at least 5 years old and they will not bear fruit fully until they are 10 years old.
How much work is involved?
Initially, soil preparation could take 12 months, as many of the Hunter soils are clay-based and need to be improved before planting. The usual problems are acidity (add lime) and high salt levels (add gypsum). Some areas also have high Magnesium, Aluminium, Manganese and other imbalances.
In addition, much of the area has low organic material levels so a cover crop (such as lupins, oats, rye, etc) to be grown and ploughed in should be considered. One very effective technique has been to plant the trees on raised mounds to aid drainage away from the roots.
All this should be done before planting as it is so much easier when there are no trees in the way! Once planted the trees need to be protected against attack from rabbits, hares and kangaroos. The frequent storms and strong winds in the area mean the trees need to be firmly staked, and regularly checked to ensure the stakes are still doing their job.
It is general practice to train the trees to a desired shape for harvesting, so allow 15 minutes a tree to shape them. 15 minutes doesn’t sound much, but 250 trees means over 60 hours!
Regular irrigation and fertilisation should ensure good growth, with more pruning and shaping. Keeping the weeds under control is especially important in the early years when the root area is small and the tree is competing with the weeds for nutrient.
Pests need to be kept under control. These range from birds eating the fruit, through a variety of insect and scale pests, through to fungal problems. These are all fairly well understood, and a range of chemical sprays (some organic) are available.
Picking
Picking - by hand or machine? Whose hands or whose machine? To strip 15kg of fruit from a 5 year old tree by hand, just picking onto a tarpaulin on the ground, took around 30 minutes per person per tree.
That is about 15 trees a day! 250 trees in around 17 days, but you do tend to get bored after a bit . All sorts of harvesting devices are available and new ones appear every month. Full mechanical harvesting using butt shakers is envisaged for trees older than 8 years.
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