| Source of technology and funding | National agricultural research system (NARS) of Tunisia; Mashreq–Maghreb Project (M&M); International Centre for Agricultural Research in the Dry Areas (ICARDA); International Food Policy Research Institute (IFPRI); funded by IFAD and the Arab Fund for Economic and Social Development (AFESD) |
| Expected Benefit: | Increased income for resource-poor farmers; reduced soil erosion; improved rangeland productivity; improved animal feed security; drought mitigation. |
| Crops and Enterprises: | Rangeland; livestock in low rainfall areas; alternative crops |
| Agro-ecological zones: | Arid and semi-arid, frost-free zones of the world |
| Target region and countries: | West Asia and North Africa (WANA), Latin America, southern and eastern Africa, southern Europe, Sahel |
| Keywords: | low rainfall areas; Opuntia; rangelands; erosion; livestock feeding |
Reasons for the increased importance of cacti in arid zones
The increased importance of cacti, such as Opuntia species, in arid
zones is because of their ability to (i) grow in “deserts”
and their drought tolerance; (ii) produce forage, fruit, and other useful
products; and (iii) mitigate long-term degradation of ecologically fragile
environments.
The various Opuntia species have developed phenological, physiological
and structural adaptations favouring survival in arid environments, in
which water is the main factor limiting the development of most plant
species. Pre-eminent among these adaptations are asynchronous reproduction
and its crassulacean acid metabolism (CAM), which combine with structural
adaptations, such as succulence, to allow this plant to continue the assimilation
of carbon dioxide during long periods of drought. In this way, acceptable
productivity levels are attained even in years of severe drought.
They can develop in severely degraded soils, which are inadequate for other crops. Opuntia spp. have a great capacity for adaptation and are ideal for responding to global environmental changes. Their root characteristics avoid wind and rain erosion, encouraging their growth in degraded areas.
Marginal lands are fragile ecosystems, and when subjected to ploughing and indiscriminate vegetation removal the result has been large-scale degradation and destruction of vegetative cover. The increasing scarcity, if not disappearance, of several plant species indicates the magnitude of genetic and edaphic losses.
Significant achievements in desertification control using cactus
To reverse the desertification trend and restore the vegetative cover
in marginal arid and semi-arid areas, appropriate integrated packages
can be applied for rangeland monitoring, livestock husbandry, and natural
resources conservation. Spineless cactus (Opuntia ficus-indica), a drought-
and erosion-tolerant plant, is being used advantageously in Tunisia, Algeria
and Morocco to slow and direct sand movement, enhance the restoration
of vegetative cover, and avoid the destruction by water of the land terraces
built to reduce runoff.
In
central and south Tunisia, cactus plantations provide a large amount of
fodder for livestock and play a key role in natural resources conservation.
Land terraces are easily damaged by water runoff, but use of cactus helps
to stabilize them, with its deep and strong rooting system. Two rows of
cactus pads are planted on the inner side of the terraces (Figure
1). The rooting system is enhanced by the availability of the water
collected at the base of the terrace. Roots are widely spread on the elevated
land part and penetrate deeply in the soil to ensure stability of the
terraces. In addition, cut-and-carried pads provide feed resources during
drought spells.
Cactus
can be used in combination with cement barriers or cut palm leaves to
stop wind erosion and sand movement. It will fix the soil and enhance
the restoration of the vegetative plant cover (Figure 2).
CommonAl planting techniques
Spineless cactus has been used for several years on a very large scale
in arid and semi-arid areas of North Africa. About 500 000 ha have been
planted in Tunisia for rangeland improvement and erosion control in areas
where rainfall ranges from 150 to 400 mm/year.
Several establishment techniques for spineless cactus are used according to the cropping systems, the farm size and the agro-ecological characteristics of the areas. Densities vary from 300 to 8000 plants (double pad) per hectare. Spaced rows, following the furrowing contours, are established to create minimum disturbance of the soil surface and existing vegetation. Double pads are then planted, slightly inclined, on the edge of the row, with the bottom two thirds of the pads buried in the soil.
Rangeland
areas and productivity in WANA countries are decreasing dramatically and
can currently provide only a small portion of livestock needs (Figure
3).
According to the land tenure system, several techniques of planting shrubs and cacti are used.
- On communal rangelands, introduced species are planted in rows without removal of natural herbaceous or woody natural species.
- On private lands, an alley cropping technique is preferred, where farmers can crop the area between rows when rainfall conditions are favourable.
- When water and soil conservation techniques are being implemented on either communal or private lands, shrubs and cactus are planted following the contour lines in order to consolidate (reinforce) the so-called tabias.
- The oldest planting technique is the bosquet type, which is a very dense plantation surrounding the house and used both for fruit cropping and for fodder to supplement animal feeding indoors.
A participatory approach predominated in Tunisia in the implementation of such planting activity. The farmers’ contribution consists of ploughing the soil, planting pads and maintaining planted areas for three years, while the government provides cactus pads (USD 0.03–0.04 per double pad), reimburses part of the farmers’ expenses (soil preparation (USD 8.55/ha), planting (USD 34.20/ha)), and provides subsidies (USD 38.50/ha annually for three years). The subsidy is given in kind, as concentrate feed, and corresponds to the 3-year period during which livestock is prohibited from grazing the planted area.
