Designing the Olive Grove

Who rules on Spacing, Training and Harvesting?

Conventional statements: 1. At planting we fix the lay-out, after a couple of year it’s time to decide the training

shape, at the first yield we will deal with how to harvest. 2. The training system to adopt depends on the olive variety. 3. For this variety in this environment, the most effective spacing for an olive grove is

….. tree per hectare.

No management option is a standing alone alternative. Overlooking the connections of spacing, training and harvesting has negative economic consequences. In this writing I consider how each decision is linked from the previous one.

Input 1: Defining the Harvest Technology. Although, quite often the choice of the harvest system is faced only when the grove actually turns into production, it is wise to define it from the very beginning. In fact, being the harvest one of major expenses, it’s worth considering it as the key element for limiting production costs.

harvest and transport

soil tillage and weeds control

irrigationfertilisation

processing

spray

pruning

Incidence on the total cost of the different practices in the management of an intensive olive grove.

Any figure involves high level of approximation since factors change in different areas, management system, yield, years. The grove size is crucial for defining the most appropriate harvesting equipment. The number of plants or the expected quantity of olive to harvest must cope with the equipment (i.e. its costs and harvesting efficiency). Therefore large grove owners will conveniently afford efficient and more expensive equipments that in smaller grove would result oversized.

Harvesting systems can be categorized on the base of their technological level and operating efficiency:

Combing devices. Equipment efficiency is expressed as kg/hr. Harvest efficiency increases with -high yields per tree, -appropriately pruned canopies, - short trees.

Equipment efficiency is expressed as kg/hr. Harvest efficiency increases with -high yields per tree, -appropriately pruned canopies, -short trees. Some skill is to be acquired.

Equipment efficiency is expressed as trees/hr. Harvest efficiency increases with high yields per tree, appropriately pruned canopies and high trees. The machine operator is highly skilled. The efficiency of workers at the nets becomes crucial.

Equipment efficiency is expressed as km/hr. Harvest efficiency increases with high yields per tree and appropriately pruned canopies. The machine operator is highly skilled; the pruning team is crucial in order to avoid damages to the canopy. These machines operate only on plane.

From the manual devices to the straddle harvester harvesting efficiency increases (and so costs do). The larger is the orchard, the more it will be worth paying for a more efficient machine. In order to identify the most efficient and effectively affordable harvesting device, is is important to calculate the machine breakeven in surface units. Whether the equipment is also used by others (neighbours) or for other crops (trunk shakers also harvest almonds, cherries, etc.), calculation of the breakeven point must take account of these additional uses. At the breakeven surface, the total costs (labour, fuel, spare parts, etc. and equipment depreciation) is equal to the value of harvested (operating income is zero).

Depreciation + operating costs = value of harvested olives

hectars

€Operation Exp.

Depreciation

In small groves, the machineries will not be repaid (at least not in reasonable depreciation time), while it will occur in larger groves. As for the value of harvested olives, it is important to consider the final product price. This is directly available if olives are sold as raw material, while whether bottled oil is traded, the oil price should be subtracted of labelling, bottling, stocking, pressing and marketing costs in order to obtain the harvested olive value.

hectars

€

Total expences

Value ofharvested

Breakeven point

hectars

€

Total expences

Value ofharvested

Breakeven point

The training system Since every machine has different tree shape requirements, harvesting efficiency strongly depends on whether trees are pruned i accordingly. There are many olive training systems (and probably as many interpretation of them as pruners). Each was designed after specific needs and there is not a best of all. Once the most suitable harvesting equipment is defined, only few shapes and training systems will allow lead to high efficiencies. Machines with combing heads requires fruits easily reachable in the canopy, possibly on long and leaning shoots. Canopies from different trees should develop a green wall, not too low on the ground nor over the height reached by the device. Hooked devices best perform onto small horizontal branches about 2 m. high, bearing short fruiting shoots. Vibration induced by trunk shakers transfers upward to the highest shoots but very poorly horizontal. So these harvesters better perform with short horizontal branches and high trees. In order to minimise losses (un-fallen olives), the training systems will bear branches pointing upward: cone vase, single leader shape or similar free forms. At the base, canopy must not get too much wide or the vibrations will not shake the olives lively enough to detach them..

Input 2: Referring to a Tree Model. There are endless environment and technical factors affecting tree development: olive cultivar, soil quality, climate, availability of irrigation, field exposure, soil, etc.. Each of them interacts with all others. Reading them separately would be a mistake. When possible, instead of an analytical analysis of environment indicators, it is worth observing other olive trees living in the nearby and how the environment as a whole affects their growth. Such observation is very useful and could provide a starting point setting the expected canopy size. The reference tree should be: possibly of the same variety or of a variety similar for vigour to the one(s) to plant, adult tree and regularly producing,

in good health, un-pruned for the at least 12 months.

The width, the height and the volume of the canopy are the most significant parameters. It might be useful to correct them whether the model trees and the plants to be planted differ for vigour.

From a Model to Actual Lay-out Once fixed the training system and forecasted the sizes of the tree it is possible to calculate the covering surface per single tree. Then, two main assumptions rule on:

1. At full growth 40-50 % of the surface must remain un-covered. This is to permit the penetration of full light all over the canopy. For trees growing wider than higher, 40% of the surface should remain un-covered; if higher than wider, 50% is more convenient. In dry farming, 50% is the best ratio regardless the shape. We get then the total surface needed per single plant.

2. An easy access and manoeuvring for machineries is crucial; all operating machines and

tools must be considered. As for the distance between trees along the row, it is convenient to use the closest distance suitable for trees => square root of total surface needed per single plant; As for the distance between rows, it is to be set according to the needs of access, backing and manoeuvring of tractors and other equipment and can be wider than the previous one. Therefore, by recurring to the size of the plantation and a tree as a model, it is possible to define the most suitable:

harvesting equipment, tree training system and pruning technique, plantation layout.

Training System

Spacing

(mechanical) Pruning

Grove Width

Harvest Equipment

Tree Size

Machinery needs

Further comments: Some cultivars develop differently from others (vigour of the variety) and may

require some further adjustments in spacing calculations. Often it is recommended to orientate the rows along the North-South axis so as

canopies get the most efficient light exposure. Although the North-South axis rule has relevance in large groves where slopes and contours are not relevant. In small and medium size fields, the actual row orientation is normally set as to create the longest rows.

In dry farming, roots compete for water and need wider volumes of soil. On the other side, it would also be a mistake to adopt closer spacing in irrigated groves since irrigated trees develop bigger. Better to adopt standard spacing even where irrigation is provided.

Quality tip: In most areas, the harvest season useful for the production of top quality oil lasts no more than 40 -50 days. Should quality be a major goal, the equipment efficiency must permit to accomplish most of the harvest within this time. Organic tip: There is a number of crops that can grow among the rows of the young olive trees: asparagus, artichokes, many other vegetables. The olive trees will benefit of the fertilisation and the watering to the seasonal crop and the grower will keep the land productive. Avoid tomato, eggplant, pepper and any other Solanacea; they infect the soil with the fungal parasite Verticillium, dangerous to olive trees.

What if the spacing is too wide? What if it’s too narrow? Within some limits, ordinary pruning is a system for compensating some mistakes occurred at planting. The plants themselves, by growing towards the light, will assume an adapted shape. In case of a too wide spacing, the plants have full light and grow wealthy. Everything looks fine but the full productive potential of the environment is not achieved or is achieved only after many years (with huge trees). Planting new trees between the rows could lead to other problems: plants growing too close and little space for operating machineries. Further, young plants grow slowly behind the shadow of big trees. New plantation can be considered in combination with a change of training system of present trees can be considered but this means new harvesting systems or a loss in harvest efficiency. If plants are placed too close, the consequences are obvious: the lower part of the canopy have few, weak yellowish leaves, and all the new sprouts are growing on the upper part of the canopy. Lower leaves can also be covered by a dark sticky powder. Fruit setting is concentrated on the higher canopy levels. The grass on the ground does not grow and some moss might appear. Trees look healthier and greener, at the boundaries.

1. At planting the grove planner must have already decided the training shape and how to harvest; the lay out and the spacing are consequences.

2. In spite of some olive variety suiting certain shapes better than others, all training shape are possible for any cv.. Economics and cost accounting are the starting points when deciding the training shape to adopt.

3. Cultivar and environment are not the only factors to consider for an appropriate lay out. It is important to take into account decisions related to production costs as tree training and harvesting equipment.

i Although other factors (the length of the olive peduncles, the olive weight and size, the resistance to snap, the length of the bearing shoot, the internodes length and others), are pointed as crucial, according to my experience, for cultivars bearing fruit not too small, a correct tree structuring is by far the main factor to consider.