Olive Agencies Information Services


The fertiliser requirements of an olive orchard are not complex. Traditional fertilising has always been simply done with natural well rotted manures and  mulches. This method ensures that all nutrients applied are readily usable by  the trees. It also reduces the possibility of over fertilising which can have detrimental effects on the trees, the soil, and the underlying water table.

Olive trees are 'natives' of the Mediterranean countries and therefore they  should be treated as such even when introduced into far off lands such as Australia. They're similar in their cultural needs to our native trees such as  eucalypts. In light of this, regular or large applications of chemical fertilisers may do more harm than good. Controlled chemical fertilising can  produce good crops, however it must be carefully monitored to ensure no damage is done.

There are many manures which are perfectly suitable for olive orchards. The  one rule which must be kept in mind is that no matter which manure you choose or have access to, it must be well rotted before being put onto the orchard.  Fresh manures can burn the roots of the trees. For details on fertiliser  requirements at planting see OLIFAX - 3.

A manure which we use as an example and recommend due to its well rotted and balanced nature is the manure found in meat chicken sheds. The floor of the shed is covered with a layer of sawdust prior to the chickens arriving. The chickens then spend a number of weeks manuring on and scratching around in this sawdust  as they grow. After one or two batches of the grown chickens are removed, the  well mixed sawdust and manure is removed from the shed and heaped into piles.  This product is ready to be placed on the olive orchard. (NB. You cannot reproduce this product simply by mixing one tonne of fresh sawdust with one  tonne of fresh chicken manure as both ingredients must be well mixed and composted prior to reaching the trees).

Well rotted manure from horses, cattle, pigs and sheep etc are also quite  suitable. Just remember the 'well rotted' rule. Due to the relatively slow release of nutrients from manures into the soil, they tend to keep the soils at  healthy nutrient levels throughout the season. One application of rotted manure after harvesting and pruning is generally enough to get the tree through until the following winter. Spread the manure 25mm (1 inch) deep over the total  under-canopy area (ie. The area in shade if the sun is directly above the tree).  Leave about 100mm (4") clear around the trunk to remove any chance of burning the tree. Ideally, the manure can be spread out as far as 300mm (1ft) past the canopy because olive roots do extend further than the canopy.

Chemical fertilisers are often applied in a liquid state for ease of application and speed of infiltration into the soil. Remember, chemical fertilisers can be utilised efficiently in an olive orchard but they must be carefully monitored to avoid excessive applications. Chemical fertilisers are  generally less expensive and easier to apply than manures.

There have been numerous accounts of growers overfertilising their olive orchard by using the same quantities and strengths of chemical fertilisers as they put on their citrus or stonefruit orchards. Remember, olives are native  trees and don't appreciate large doses of chemical fertilisers.

One detrimental effect of over fertilising is that it can lead to excessive  foliage growth which requires heavy, time-consuming pruning to bring the tree back into balanced production. This 'growth effect' is something that can be read about in books but is most easily learned through experimentation in your  own orchard.

Details on the diagnosing and correcting of specific nutrient problems can be  found in the Californian Olive Production Manual. (This can be bought through our office or directly, but more expensively, from California).