What is ICM?
An ICM (InterCropping Model) is a model where different kinds of crops are planted together. Mono-culture is the opposite; where one crop is planted as what you see on the photo below.
Why Monocropping in developed countries?
This photo seems to be of a big commercial plantation. Probably all of the macadamias are grafted high yielding varieties of the macadamia nut, and the owner might have the best consultation about fertilization and IPM (integrated pest management). Perhaps the owner also doesn't need to use his land to produce ood for own consumption. And it seems that the owner invested a lot of money, while the first yield will be after at least 4 years after planting; even when grafted. Such big investments is a big risk in corrupt countries, because the farmer must be sure to sell the nuts after 5 years of growing, but in most developed countries they can count on each other: The bank is able to give a loan to the farmer, the government provides land to the farmer with infrastructure, the processor guarantees to buy all the nuts after 5 years. And they all know that they need each other to create and to keep a supply chain running. At the end the total size of the land is perhaps 100 times bigger as a farmer in a developing country and even the yield/acre is much higher. Moreover, the great cooperation within the supply chains and their competitive power will give each party involved a great income out of macadamia production. Perhaps even so big that it will be enough to give provide an unemployment benefit to every former farmer of whom the land is bought from. So in those circumstances mono-cropping could be good; however, even when such opportunities are at stake there are still reasons to use ICM above (MCM) mono-cropping models.
Why Intercropping in developing countries?
For developping countries it is much better to pioneer in farming with intercropping models. Here are the reasons:
1. Less risk to depend one crop
Most developping countries struggle with corruption and there is no bank who believes in a plantation plan where the first return will be ater 5 years. It is therefore better to cultivate more than one crop at the farm. And not at a different area, but mintercropped (mixed) together; as the following reasons explain the ecological benefits of that.
2. It's a waste of space to start with such a wide planting distance for the slow growing macadamia tree
Macadamia should have a planting distance as at the picture above, but that is actually not true for the first 10 years. Especially in semi-arid areas it is good to have a dense planting distance because of the following reasons. In the first year annual crops such as maize can be harvested, in the second year bi-annual crops such as pigeon pea can be harvested, in the 10th year secondary crops can be harvested for timber, fodder, or timber, and only then the macadamia requires a planting distance of 9 x 9 meters.
3. The 10 years of intercropping other crops provides income and even ecological benefits
If the right crops are selected for intercropping it will not only give a return but even improves the land ecologically. However, only if the appropriate crops are used or intercropping. The InterCrop Models of this website will be models to select such crops by filtering the database on special requirements. The benefits that crops can provide to surrounding crops are as follows:
Nitrogen fixation
Some plants are able to fix athmospheric nitrogen in symbiosis between root and bacterias. The nitrogen which was gas will be released in solid or liquid form via the roots and via decomposition of plant material (slow releasing nitrogen). And in most tropical countries; nitrogen is the most decient soil element.
Mining of other soil nutrients
In this database trees are categorized in either shallow or deep root-systems. Macadamia has shallow roots and the grasses at the photo above as well. In MCM where only one species is grown; the roots are all at the same depth, the same type of nutrient is removed from the soil, the same type of insects are attracted, and the natural balance will dissapear. While at ICM there are many different kinds of species with different root-depths, and diferent requirements and contributions in the soil. Sometimes when there is scarcity of nutrients the deep rooted trees can mine them from the soil and release them to shallow rooted trees by decomposing litter.
Re-introducing Mycorrhyza
There are plants that react very well on symbiotic root/fungi (mycorrhiza) and spread those beneficial ungi to surrounding plants. The plants provide sugars as food for the fungi as they also provide sugars for its own roots to find water and nutrients, and in turn of that the fungi provides nutriets and water for the plant. Sometimes the fungi is able to dissolve micro-nutrients and phosphorous minerals, which plants cannot do at its own. Mycorrhiza requires a constant living host and at most farms there are periods of uncultivated land: This will kill the mycorrhiza in the soil and will only come back by seedling innoculation or via spores via living plants that still have that symbiotic fungi. Glomus intradices is one of the best fungi for mycorrhyza in the soil. By innocluating this fungi in a nursery to specific plants that react very well on this type of AM-fungi will be a great benefit to all crops in the field that are intercropped, as they will also get this beneficial fungi.
Providing shade from drought tolerant plants to less-drought resistant plants
There are very fast growing species which are very drought tolerant. It they provide partial shade to less-drought resistant primary crops; it can safe water; however, for some species; such as Eucalyptus species it is not always correct to state this theory because they are also very drought tolerant, but they still consume very more water than most others. But Albizia lebbeck, Casuarina, and Moringa trees are very drought tolerant, they fix nitrogen, and they produce a thick layer of mulch (slow decomposing litter) above the soil. And those trees lose much less moisture than most other crops, so it will be good if those trees will overshadow the less-drought resistant crops; such as grasses and macadamia trees.
4. Providing mulch
Many tropical crops require a rich organic top soil and a layer of mulch for their shallow roots. So it is good to intercrop species that fix nitrogen, produce a layer of mulch and grow fast in bio-mass production.
5. Ornamental benefits
Intercropping Systems resemble more as a natural forest and can be very ornamental. It might attract tourism, nature activists and communities to use their land for such ICM that is ornamental, ecological, and even economic.
6. Less maintenance
As the ecological benefits make clear is that much of the nutrients and water can be controled by intercropping diferent plants in the right order. In nature different trees are also growing very well without IPM, irrigation, or fertilization.
7. Apiculture
The bee population decreases by mono-cropping where they try to keep the natural balance by pesticides, fertilizers, and irrigation, but bees die from pesticides. The farm should have a lot o bees for pollination and optionally for honey production.
8. Distinct vegetative stage and fruiting stage
Most fruit and nut species flower after 5-10 years and some of them have off-seasons. That means that that in some years the yield is low and in the other year the yield is high. There are diferent ways to influence vegetative and fruiting stages. In the first 10 years when the primary crop is intercropped with other crops is a vegetative stage: There is more nitrogen available, less sunlight/space, less other nutrients. And in the period when the macadamia requires its 9 x 9 meters spacing the intercropped plants will be harvested and the litter relaeases soil mined nutrients. There will be more sunlight (which triggers lowering) and less nitrogen at the end (also triggers flowering).
Keeping the tree in a prolonged vegetative state at the beginning will give a distinct on-season instead of off-seasons. Moreover, it is even written in the Torah to eat only from fruit trees after the fourth year because it will give higher yields in the end accordingly.