Family: CAESALPINIACEAE
The carob is said to be the largest (to 15 m) of Europe's leguminous trees, and is a native to the Mediterranean region. It grows in minimum rainfall areas of 250 mm, but does better with higher rainfalls. It is sensitive to cold below - 4°C when young, but mature trees suffer little damage at - 8°C. These evergreen trees can spread their crowns out to 10 m and prefer slightly alkaline, sandy soils with good drainage, but will grow in virtually any soil including rocky ground, but with the exception of compacted clay. Their life span is 500 or more years.
They are generally dioecious, requiring male and female trees to set pods but are occasionally hermaphrodite. The pod is a fleshy bean up to 300 mm in length and is both flavoursome and nutritious. The ranges of reported nutritional analysis are: Crude protein 2.25 - 21.0%; Crude fat 0.5 - 1.5%; Crude fibre 4.65 - 13.3%; Nitrogen free extract 74.1 - 75.97%; Ash 1.52 - 2.8%; Calcium 0.13 - 0.28%; Total sugars 37.1 - 56.6%. The pods are excellent stockfeed, commer-cially sold as chocolate substitute human food, and the seed contains gums with industrial uses. The bean also has potential to produce alcohol fuel.
Yields of 1 tonne of pods from a single tree have been reported from some trees in a good season, but about 10% of that is more likely and would still yield in the order of 8 t/ha. West-ern Australia is fortunate to have gained budwood from a carob variety collection in California that was destroyed by urban sprawl. This collection was brought to W. A. by Henry Esbenshade, and will be used as a source of scion wood for nurseries and land holders.
Australia spends about $60,000 annually on imported carob powder and demand has been increasing at about 20%/yr. Machinery to powder carob pods is not a complicated arrangement and could be shared amongst a group of farmers. If farmers took the trouble to powder their pods, they could expect a year 10 return of $6,765/ha with full irrigation, $3,025 with minimum irrigation and $ 1100 with no irrigation, at a planting density of 90 - 100 trees/ha. (1985 prices)
Some degree of salt tolerance has been observed in carobs growing along waterways and in low lying areas in both Australia and Israel. The carob tree is reported to not burn easily, and when scorched by fire, it generally recovers. Stock will also trim the foliage to within their reach, but no work appears to have been done on the nutritional values of the foliage.
They have been grown in Algeria as companions to grapes with good results. They grow well with tagasaste, Albizia lophantha and Acacia decurrens as nurse plants.
Tap roots of mature trees have been traced down to 20 m. A carob seedling develops a long tap root at a very early age: about 250 mm in the first two weeks (from germination). Trees that remain in shallow pots do not develop ideal root systems and lose the advantage of drought tolerance.
Direct seeding of carobs is possible and is best done using protective markers such as old tyres. However during germination, moisture must be maintained, so it is often desirable to start the seedlings in deep pots and move them out after a couple of weeks. One litre milk cartons with a few drainage holes punched in the side near the base make ideal starter pots.
Carobs can be sown at any time of the year, although young seedlings are frost susceptible. Seedlings may be protected in the field using clear fertiliser bags and stakes as improvised mini -hothouses. Establishing the trees over summer eliminates the frost problem, but watering is necessary. It is often convenient to arrange planting so as not to conflict with other seasonal activities. For example, establishing the trees in the wheatbelt before the rain "breaks", means that the farmer is free to attend his crop after the first rains, and the carobs will require no special treatment.
Carob seeds have very hard protective cases and need to be scarified (cracked). The easiest method is to pour boiling water over the seeds and allow them to soak overnight. Repeat the procedure on any seeds that have not swollen. The seed can then be sown into pots.
Planting out: when transplanting the seedling, it must be removed from the milk carton. Using a sharp knife, cut the base from the milk carton and run a cut up one side of the carton, being careful not to penetrate into the root system. Gently place the seedling, still in its carton, into a prepared hole so that it sits on firmed - down soil and so as to place the seedling at ground level. Lightly fill around the pot, then slide the carton vertically up whilst holding the seedling in place.
Water well and press the soil firmly around the seedling, leaving a slight depression around it so water can collect when rain falls.
Closer planting of seedlings, allows for natural deaths and final selection of better fruiting females and well placed males. This selection can be made after the first couple of seasons of fruiting (7-8 years), or alternatively, known cultivars can be grafted onto the rootstock to produce a certain crop at an earlier stage.