Olives for integrated livestock-orchards

I’ve been doing an awful lot of research, recently, into integrated agroforestry and pastured livestock farming systems. Specifically the system of pasture and productive woodland common to the Iberian Peninsula (Spain and Portugal) which is commonly called  dehesa, or montado in Portugal.


Although the traditional dehesa forests are primarily made up of cork oak (Quercus suber) and holm oak (Quercus ilex), the system could work with any number of tree species. It’s basically a Mediterranean silvopasture system, with scattered tree cover (using trees which produce some sort of commercially valuable product) with pasture and animals grazing underneath. Traditional dehesa systems often include pasture raised pigs, which are fattened in the autumn on the acorns dropped by the oak trees and then slaughtered to make premium jamon iberico. The fallen leaves of the oak trees are also a useful fodder resource for pigs, sheep, goats, and cattle, supplementing the available pasture.


In an Australian context it turns out that oak trees aren’t really the way to go unless you’re planting a forest for pleasure. There’s a limited international market for cork (and even more limited domestic market), and the trees take around 25 – 35 years to produce a viable cork harvest (and can thereafter be harvested only every 9 – 10 years). There is no existing market for acorns, in spite of their value as pig feed, and the fact that when they’re properly processed they are entirely edible to humans too. And they’re gluten free, but provide a similar gumming capability to gluten, useful in baked goods.


Rather than oak trees, an Australian dehesa style system would work best if it used trees which produced a crop faster, and one for which there is an existing market. That still leaves several options, and the choice depends largely on the local climate (rainfall, available chill hours and heat units) and on what type of livestock will be included in the system. For example, apples or plums are a great option if (a) your region gets enough rainfall for them to thrive, (b) your region gets cold enough for long enough over winter to ensure good fruit set, and (c) you want to keep pastured poultry (turkeys, chickens, or geese will clean up windfall fruit and help control fruit fly, but won’t eat the foliage of the trees – which is potentially toxic). In warmer and lower rainfall regions, some of the best options in terms of market value, yield and productivity are date palms, pomegranates, and pistachio nuts. And olive trees.


Olive trees are appealing because they’re already widely planted, and there’s a huge market for both table olives and olive oil. The commodity prices may rise and fall, but it doesn’t look like the demand for olives and olive oil are likely to drop significantly any time soon. And of course, olive trees are beautiful, graceful trees which never fail to make me happy when I see them. One of my fondest memories from travelling in South America was the 100 year old olive grove in Lima, Peru; gnarled, old trees which had clearly been pruned and trained so that they could be easily harvested. They were in this tiny park on a median strip in the middle of a huge, super busy road, but they were still so peaceful and majestic. Yeah. I like olive trees.


We use olive oil for almost everything ourselves, and we go through about a litre of the stuff every six weeks. Sometimes a bit more, if I’m doing a lot of baking that month (yes, you can replace the butter in most recipes which call for butter with an equivalent volume of olive oil). Since the average yield for a mature olive tree is anywhere from 30 -80kg olives per year (averaging about 45kg per year for a ten year old tree), and the oil yield ranges from 12 – 21% (but averages around 18 – 20%), I worked out that six olive trees would more than cover us for our olive oil needs, and another six for all the table olives we can possibly eat. So I planned on twelve olive trees. We have seven in the ground already, so I went to order the remaining five – and promptly ordered twelve instead, because.. well.. olive trees are so lovely and I wasn’t sure which variety to get more of so I got three of each. The varieties we have are: Kalamata, Koroneiki, New Norcia Mission (a variant of Frantoio), and Manzanillo. They last week (ordered from Mission Horticulture, who were great), and will be going into the ground this week.


The other joy of olive trees is that the tree is remarkably multifunctional. The foliage can be eaten by ruminants (and pseudo-ruminants like rabbits), although due to the tannins it isn’t hugely nutritious. The raw fruit can be eaten by poultry and pigs, and I can’t vouch for the nutritional content but the chickens seem to love raw olives. Weird birds. They’re not harmful to ruminants either, although not necessarily beneficial, so you could keep just about any livestock under olive trees. The leftover press cake from pressing out the olive oil can also be fed to ruminants or poultry, and there are studies to show that it is actually reasonably nutritious, high in protein and energy. The tree is evergreen, and provides a lovely cool shade which still isn’t deep enough to kill grass or flowers grown under it. Trees which are big enough are eminently climbable, with smooth, greyish bark which is a delight to the climber (yes, I climb trees at any opportunity). The timber (from pruned branches of course – who would cut down an olive tree??) is a beautiful golden colour with grey-green highlights, and is good for turning. And of course, olives and oil.


We’re not planning on producing olives or olive oil commercially, although we could.  The recommended planting density for a commercial orchard is anywhere from 100 – 500 trees/ha, but in a dehasa style system that would be lower. Maybe around 50 trees/ha, and livestock at 1 – 4 dry sheep equivalents (DSE)/ha. We’ll produce enough for ourselves, and once the trees are mature we may produce enough for friends and family. But that doesn’t change the fact that olives are a pretty good bet for a changing climate and a world poised to head into some tough times over the next few years. They’re tough, adaptable trees, and they thrive in our soils and with the fierce Australian sunshine while producing amazing food. They’re an example for the rest of us, really.


* DSE is the standard measure used for livestock density in Australia. A lactating ewe with twin lambs is about 2.4 DSE, a goat is about 1.5, and a cow is about 10 DSE. The measure refers to how much pasture an animal needs to eat each day to maintain body weight and health. DSE are not used for poultry or rabbits, but are sometimes used for emus and ostriches as well as the standard cattle, sheep, goats, alpacas, etc.