Salah Chouki, Office de l’Elevage et des Pâturages.
Different types of Opuntia ficus-indica, cold and drought tolerant are present and spread in the arid areas of the WANA region, where the average amount of precipitation varies from 200 to 800 mm per annum. For years, spiny cactus was used primarily, as hedge of rural homes while spineless cactus was used around houses usually on previous sheep barns. Cactus in Tunisia is mostly localized in areas characterized by low quality soils and scarcity of water for irrigation, which indicates that these plants are more, adapted to the dryness of the climate and the fragility of the natural conditions of the rangelands. Along the years and because of its high resistance to the environmental stresses that prevail in the dry areas affected by the consequences of frequent and severe prolonged droughts on livestock, the use of cactus is being very important for agricultural communities. It is considered as the most important feed source for sheep during the dry season of the year. It is also been useful in controlling desertification, improving depleted natural rangelands by preventing long-term degradation of ecologically weak environments.
Thus, spineless cactus cultivation has become an important crop for the subsistence agriculture of the semi-arid and arid regions. Several bilateral projects and local programs have promoted the establishment of spineless cactus to orient the utilization of the plant for multiple purposes:
Spineless cactus, at large scale, was used in early sixties (PAM program), where plants were used to provide a source of forage reserve to feed sheep flocks in Central and southern regions of the country. However, several factors, such as techniques of establishment -plantation of single pad-, introduction of cactus in inconvenient areas - water logging and clay soils-, misuse of established plants -direct grazing and overgrazing-, severe drought and cold years led to the loss of thousands of hectares. The only areas are found to be maintained are those planted around the rural homes, which they provided the main source of providing pads for further expansion. Meanwhile, it is learned from this previous experience that cactus is well adapted to the harshest zones and with some corrections, it can be considered as an important mean to improve marginal and not suitable for agriculture lands.
These elements encouraged bilateral projects and local programs to promote the use of spineless cactus to improve natural rangelands, improve the farmers' revenue and provide feed source at the most difficult seasons.
Thus, spineless cactus was, at the first time, one of the major techniques to improve rangelands in Central Tunisia in early eighties (Range Management Project of Central Tunisia, USDA project 1982-1989) followed by a national program beginning in 1990.
At the present time, there is a growing area of 450 000 ha located mainly in the east and west central of the country.
Methodology of cactus implementation on private rangelands
The participatory approach the is the main option followed in the implementation of such activity. The farmers’ contribution consists on plowing the soil, planting pads and maintaining planted areas for three years, while the government provides cactus pads (from 0,04 to 0,12 US$ per double pad), the payment of part of farmers’ expenses [soil preparation (8,55 US$), planting (34,20 US$)], provide subsidies (38,50 US$ per hectare per year for three years).
Techniques of establishment
Several establishment techniques of spineless cactus are used according to the cropping systems, the farm size and the agroecological characteristics of the areas. Densities vary from 300 to 8 000 plants (double pad) per hectare. Spaced rows, following the furrowing contours are established to use and disturb at minimum the soil surface and the spontaneous vegetation. Double Pads are then planted, lightly inclined, on the edge of the row with the two third of the bottom pads buried in the soil.
Figure 1. Distribution of spineless cactus plantation in Tunisia
SMALL SCALE CACTUS PEAR CULTIVATION FOR FORAGE PRODUCTION
Cactus pear is a plant that tolerates competition and heavy pruning. The entire aerial part can be utilized as a forage if needed. It also presents a notable response to manure and chemical fertilizers. Manipulation of planting densities and plant nutrition allow large yields of fresh pads. The broadbed planting system takes advantage of all these features. It was envisioned to be practiced in small plots (< 0.5 ha) in the backyard or near the households. These spots are usually more productive than the open field (due to the accumulation of domestic waste) and in some places they have access to limited irrigation, both factors benefit plant productivity. The labour needed to maintain the plot is provided by the family. The system can produce fresh tender pads (an advantage where there is a tradition of consumption) and/or mature pads for forage. Production is higher during summer season (the rainy season). Longer production periods are feasable in frost-free places or by providing some sort of frost protection. In this paper the broadbed system to grow cactus pear for forage production is described.
Planting sites are more convenient if located near to the households or in backyards, which allows for continuous care. If plantations are to be located in the open field then select the best comunicated plot. Fresh cactus pads are heavy feedstuff, therefore it is necessary to ensure quick access to roads in good conditions any season of the year.
The site should be preferably flat, but slopes up to 3% can be handled with simple soil and water conservation practices such as contour planting without increasing cost of site preparation.
Eliminate perennial weeds or shrubs. Till the soil to facilitate broadbed formation. Depending on the soil type it is advisable to plow it twice. Slight terrain imperfections can be reduced by grading. Leveling the planting site improves water distribution ensuring more uniform growth.
Rainfall management is a key issue for effective plant growth. The basic idea is to reduce runnoff as much as possible. Rainwater can be collected in the site prior plantation if the field is plowed in advance. After planting the furrows that separate the beds can be ´tied up´ every 2-3 m to distribute rainwater evenly.
Spineless cultivars are the most preferred for forage production because are easier to handle and process. They are also associated with less problems during feeding. In Mexico the cultivars Selección Pabellon and CPF1 are the most suitable. Both are highly productive and posses large spineless pads Figure 1. Selección Pabellon has ovoide thick dark green pads, mature plants produce red tasty fruits Figure 2. CPF1 produces long, thin, green pads, suitable to be consumed as vegetable when tender. The fruits of this cultivar are white with thin pericarp and slight blush. Under rainfed conditions at least one flush of pads per growing season are produced.
Figure 1. Selección Pabellon a cactus pear cultivar suitable for forage and vegetable production.
Irrigation and fertilization can induce more than one layer of pads per season. Recorded yields of fresh mature pads without irrigation for these varieties in Central Mexico are 75 and 118 ton/ha for Selección Pabellon and CPF1, respectively.
Planting material should be collected from robust, productive and healthy plants. The pads can be collected at the end of the growing season and subjected to slight dehydration to allow suberization of the joints. Collect pads of medium to large size. After collection they are stored in a shaded dry place for 2 weeks. Pad portions can also be used when planting material is scarce, but the smaller the portion the longer the time new shoots will require to reach full size. The smallest portion that can be planted should have at least two-three areoles in each face.
To reduce rotting the pads are treated with bordeaux mixture prepared the same day of treatment. Mix 1 kg of copper sulphate in 5 liters of warm water until complete dilution, then add 1 kg of lime stirr until the mixture is homogeneus, complete to 100 liters. We estimate that his volume is enough to treat up to 2000 pads.
The broadbed system is supported on high planting density and productiviy per unit area. Several options are possible according to the machinery available. In our experience the best dimensions of the broadbed are 150 cm wide with 120 cm on top. The length is adjusted as needed. Broadbeds are built using a small (120 HP) tractor or animal traction devices. Three or four rows of pads are aligned on top of the broadbeds (separation in between rows and pads is 30 by 40 cm respectively) Figure 3. The pads are buried halfway into the ground. According to these broadbed dimensions 20 pads are needed for each 2 m lenght.
Cactus pear is damaged by freezing temperatures, a safe lower limit temperature would be 5 oC for most cultivars. Tender shoots are highly susceptible to frost damage and they start emerging after 2-3 weeks of planting. Therefore planting should be done after risk of frosts is over.
To ensure high yields it is convenient to apply manure prior to planting. Manure can be broadcasted and plowed down prior to planting. The best results are obtained when manure is supplemented with synthetic fertilizers. Chemical fertilizers are a quick source of nutrients, while manure represents a steady supply. A minimum of 20 ton/ha of cow manure every other year, supplemented with 90-40 (kg of N-P205) supplied on annual basis are suggested. These rates have to be adjusted according to the source. Chemical fertilizers can be applied during the rainy season, providing half of the nitrogen fertilizer early in the season and the rest 45 days later. The product is spreaded along the rows and sligthly covered with soil.
Management of pests and diseases
Pests that thrive inside the pads are the most destructive and difficult to control. However selective prunning can help to maintain a healthy plantation. Some rotting problems can also be solved with prunning. Some pests that live on the surface of the pads such as mealy bugs and thrips can be controled with contact insecticides. Effective control is achieved by sapraying with Sevin 80 (dithiocarbamate) 1 kg/200 liters of water.
Mature pads can be collected at the end of the growing season. They are detached from the plant using knives, with a clean stroke right in the joints. Avoid unnecesary chopping of the harvested plant or the plant to reduce risk of rotting. The number of pads to be harvested varies with cultivar and age of the plant. During the first year 2-4 pads per plant can be collected. In order to get steady yield the plants are left with only two pads ("rabbit ears") oriented alongside of the broadbed. Figure 3.
Fresh pads should be stored in a shaded dry spot. They can be either stacked or arranged in rows sitting on their sides. Avoid spots that collect runnoff to reduce the roting or sprouting. Those pads in close contact to the ground need to be turned over every 4-6 weeks to avoid rooting. They can also be protected temporarily with a thin (5-10 cm) layer of dry straw. Under the semiarid cool conditions of Central Mexico we have stored pads for up to six months without appreciable losses.
Cactus pear pads can be consumed directly on the plants, however uncontrolled browsing can damage the plants. It is more efficient to collect and stored them close to the livestock yards.
International committee of cactusnet-fao
Coordinator Technical Subgroup
Coordinator economic subgroup
Central and South Africa
Working Groups and coordinators
Pest and Diseases
Planting Genetic Resources Collection, Conservation