The importance of TOMCAT wood chippers in olive orchards

Figure 1: An olive orchard located in the Western Cape, South Africa

Brief history

The olive originated in Western Asia (also known as Anatolia) and spread from Iran, Syria and Palestine to the rest of the Mediterranean more than 5,000 years ago. It is believed that olive trees were cultivated even before written languages were invented. Some of the oldest olive trees alive today are in Greece and Israel and are estimated to be between 900 and 4000 years old. Olives can be productive for 100s of years when cultivated correctly and are not like other fruit trees that have a short lifespan. Vineyards, for example, need to be replaced every +- 25 years to justify their economic existence.

Olives were introduced to the Cape in 1661 by Jan van Riebeeck, but it was not until the 1900s that commercial farming of olives started. The most popular olive cultivars in South Africa are the Kalamata, Frantoio, Mission and Manzanilla. 

Olives when ripe have a hard structure and are extremely bitter when eaten raw. Unprocessed olives cannot be used for oil or as table olives. Olives needs to be cured by submerging them in a liquid solution in order to remove the oleuropein. After the oleuropein has left the olive it can be packed and eaten as a table olive. For oil production the olives are harvested, cleaned and then ground up to extract the oil. to An interesting fact about olives is that most oils are produced from seeds, but olive oil is extracted from the fruit itself and not the seed.

Climate and Soil

Climate conditions and soil type are crucial for having healthy, pest-free and productive fruit bearing trees. Olive trees don’t need a lot of water – they do very well in areas with an annual rainfall averaging around 800mm. The soil must have good drainage capabilities – not too much sand and not too much clay. Should the soil retain too much moisture it will cause root rot.

Olive trees prefer a long hot summer and a short winter.  They should be planted in areas where the winter day temperatures remain below 21 degrees Celcius. Should the tree experience hot weather in winter the flowers will not set and the trees will not bear fruit. Olive trees can be planted in windy areas as the tree and its fruit can tolerate wind better compared to other fruit types.

Scientific Name/ Olive CultivarCountry of OriginUse
Olea Europaea ‘Kalamon’ / KalamataGreeceBlack Table Olive
Olea Europaea ‘Frantoio’ItalianOlive Oil
Olea Europaea ‘Mission’AmericanBlack Table Olive or Olive Oil
Olea Europaea ‘Manzanilla’SpanishGreen Table Olive
Table 1: The Table above shows the most popular olive cultivars used by farmers in South Africa

The benefit of a wood chipper on fruit farms

The primary benefit of a wood chipper is the fact that it can reduce the amount of seasonal pruning waste (waste reduction unit) and reduce labour costs. The 2nd benefit and probably one of the most important ones nowadays is the wood chip produced from the waste material. The main advantages/uses of wood chips are:

1. When wood chips are applied as a thick layered mulch this will:

  • reduce water usage
  • keep your soil temperature down
  • stimulate root growth start microbial life in your soil
  • increase the health of your soil
  • reduce weed growth
  • save money by using less pesticides
  • increase the growth rate of your trees
  • ultimately increase yields

2. Wood chips are a key ingredient for making compost

3. Wood chips are environmentally friendly

Figure 2: Healthy soil will give a healthy tree. And healthy trees will deliver good produce.

A wood chipper used in an orchard after seasonal pruning has taken place will clear the branches in the same time it will take you to load the branches on a trailer and cart them away. The benefit is that there is no double handling and a lot less transport involved. The other factor to consider is that the tree has produced branches over the years, made from nutrients it pulled from the soil. Now if you cart away the branches you will have to replace those nutrients with fertilizers. If you use the branches and convert them into wood chips, the wood chips will disintegrate over time putting those nutrients back into the soil. The most cost effective way is to chip the material while slowly driving through the orchard using a TOMCAT Model 200/250 drum-style wood chipper and discharging the material directly on the “bankie”.

In the picture below (Figure 3) we went for closer soil inspection. We dove into a 10cm thick layer of wood chip mulch that has been covering the soil for about 2 years. The wood chips came from olive prunings that were chipped in the orchard and left there without being spread out. This created little “biodomes” for microbes, worms, small insects and roots to flourish. One should be careful that clay soil does not dry out too much in summer as the roots snap when the clay dries out and shrinks.

Figure 3: On the left: the same soil that has been covered in a thick layer of wood chip mulch for 2 years. On the right: Soil that has been baking in the sun for decades.
The soil covered in a thick layer of wood chip mulch:The soil not covered in wood chip mulch:
The soil is loose and can crumble easily in your handThe soil is rock hard and dry
There was still a bit of moisture present although
the irrigation was not switched on for more than a week
There was no moisture present on the top layer
There were roly polies and earthworms presentNo life visible and difficult to gain access into the soil
The ground was cool although it was 35 degrees Celsius outsideThe ground was hot
Small olive tree roots were clearly visibleNo visible roots

Table 2: This table above illustrates the differences between the picture on the left and the picture on the right hand side

Wood chips can either be discharged on the “bankie” while chipping the material in the row or it can be chipped and moved to the orchard at a later stage. Remember that the woodchips should not be stacked up against the trunk of the tree as this can cause rot to the tree base and let it die. The pictures below where taken on a citrus farm in the Western Cape and clearly show the benefits of a fruit tree in poor soil covered with proper woodchip mulch.

Extremely rocky area with base of the Citrus covered with woodchip mulch around the stem.
When the mulch is gently removed a healthy root system is clearly visible.

Article written by: Frans Greyling