Table of Contents
- 1 Producing Plants in a Nursery
- 1.1 The species concerned
- 1.2 Nursery tracking book
Producing Plants in a Nursery
The species concerned
For the creation of improved fallows, Acacia auriculiformis and Acacia mangium will be grown. These two species can also be planted in rows to make windbreaks. For hedgerows, Haematoxylon brasiletto, Ziziphus mucronata and Ziziphus mauritiana, Bauhinia rufescens, Dichrostachys cinerea and Citrus aurantifolia, the small lime, will be used.
Cashew (Western Anacardium) is a very popular species for its fruits and is used to delineate fields and orchards. All these species rise in plastic pots, never in planks. All species of hedgerows (except the lemon tree) and the cashew tree can be sown directly in the field (see leaflet on the installation of hedgerows).
Choosing the site of the Nursery
Regardless of the number of plants that one wishes to produce, the nursery site will be chosen near a permanent watering point because the production of the plants is generally done during the dry season. The nursery will be easily accessible for carts, tractors or trucks that will bring the soil or pick up the plants.
Organization of the nursery
The location of the nursery should be divided into several zones of different sizes: location for the preparation of the soil mixture and the filling of the pots, boards with shade for placing the pots, water point (bins for filling the watering cans, water tower, tap, source, …), composter, lockable premises to store equipment and phytosanitary products, access tracks. The site will be fenced and surrounded by hedgerows and windbreaks.
Some trees can be kept within the nursery to shade the places of soil mixing and bag filling. All other trees must be felled: only the shade can be used to correctly dose the shade. The nursery boards, the floor on which the pots will be laid must be leveled. On the slopes, we will make small terraces.
Breeding potted plants
The technique consists of growing potted plants so that they have, at the time of planting well-developed roots, in a soil whose water reserve allows the young plant to withstand a period of drought immediately after planting. The seeds are sown directly in the pots.
The so-called “pot” is actually a polyethylene bag, black or transparent, 80 microns thick, 25 cm high and 12 cm wide flat. Once filled, the pot is 7.5 cm in diameter and 21 cm high, a volume of just under one liter and a weight of about 1.2 kg. The bags must have holes in the lower third to ensure good drainage; a part of the holes must imperatively be located less than 3.5 cm from the base of the bag when it is flat.
The pots must be filled with a mixture of soil whose consistency allows a good holding of the pot and guarantee the plants a good mineral diet and a good water reserve while being well ventilated and well draining. The composition of the mixture will depend on the local availability of area. As far as possible we will try to put a third of forest land well supplied with organic matter, or compost, but in lesser quantity (1/5). For the other two thirds (or 4/5), soils of silty or sandy-loamy texture are ideally suited. If the soil is richer in clay (sandy-clay or silty-clay) and must be added.
The different soils are sieved (0.8 to 1 cm mesh) before mixing in the desired proportions. The sterilization of the soil, sometimes recommended, is not imperative to the extent that the earth contains mycorrhizae and rhizobia that are favorable or even necessary for the growth of many species.
Filling and storing pots
The pots are filled when the soil mixture is dry. If the soil is too wet, it is difficult to handle. To facilitate the filling of the bags, using a tin of a suitable diameter which has been removed from the two lids. The bag is threaded around the metal tube which serves to collect the earth pile.
When the bag is almost full, tap it on the ground to compact the soil and then complete the level and make a settlement again. The ground is packed enough when you can take the bag in hand in the middle without it lets go. The pots are wheeled to the nursery planks where they are stored.
Generally, it is placed side by side on fifty or a hundred rows so that each board contains 500 or 1000 plants, which then facilitates counting and monitoring. We will put earth against the pots of the outer rows to maintain them and prevent them from falling.
When the pots are installed, we complete the soil level and then we water, which still cups the earth. We add more land to the top of the pot. The pots should be well filled otherwise the plastic folds inward and cover the earth, which prevents the water from entering the soil and causes stunting or even death of the plants.
In front of each plank, there must be a sign indicating the name of the species, the date of sowing, the number of seeded pots. These same indications will be reported in the nursery logbook.
Direct sowing in pots
Most of the recommended species are sown directly in pots. For species that require it, the seeds must be pre-treated or extracted from the kernel (see “Harvesting and storing seeds”). Seeding is done with two seeds per pot. With a piece of wood, a deep hole is dug about 3 times the thickness of the seed. We put the seeds in the hole and cover with soil.
The boards are then watered. Generally, in Côte d’Ivoire, it is not essential to provide a shade for the species concerned, sown directly in pots. However, a mulch (layer of dry grass) can be placed on the boards during the germination period to avoid too much desiccation of the first cm of soil. Mulching is removed in the evening and returned in the morning, which helps control seed germination. When the seeds begin to germinate, mulching must be removed completely.
The seeded planks must be protected from ants that sometimes remove seeds, rodents that eat them and insects that eat seedlings. Poisoned baits and other appropriate treatments should be used as soon as attacks appear.
Young seedlings are frequently attacked by “pigs of seedlings”, fungi that attack seedlings at ground level. A dark ring appears at the collar, it dries out and the stem bends and falls. As soon as the first signs appear, it is necessary to reduce the waterings and to treat with antifungal: oxyquinoline (antiseptic and systemic bactericidal) gives full satisfaction to the dose of 50 g of active ingredient per 10 liters of water. A preventive treatment can be carried out a few days after the first germinations and renewed after 15 days.
Plant removal is done when the seedlings are quite vigorous, about 6 to 8 cm high, but not too late so that the roots of the different plants are not too entangled. Surplus plants should be carefully removed and the plant should not be traumatized. It is not advisable to transplant the removed plants because the pulling often damages the roots, recovery is difficult and growth is often low.
Maintenance of seedlings in Nursery
Weeding and weeding of the soil should be done regularly. It often happens that the surface of the earth “ice” after watering; this glaze must be destroyed in order for the irrigation water to penetrate completely into the soil.
The growth of the main root is fast and, very quickly, it crosses the bottom of the pot through a drainage hole and sinks into the soil in place. If this root is allowed to grow, the volume of roots in the soil will quickly become larger than that in the pot. When the young plant is removed for planting, most of the roots will remain in the nursery soil. The plant will be unbalanced: it will remain a well developed aerial part and a small piece of root. This plant will hardly support the transplant crisis or will die if there is a small drought.
The root system must grow exclusively in the pot. The roots that come out of the pot must be cut every two weeks by lifting the pots. In response, new roots develop in the pot with a strong root hair that will allow the plant to better withstand the transplant crisis. This operation, the pruning, is imperative for all species especially those with large roots, more sensitive than those with fine roots. When the pruning is too far apart, the induced trauma to the plant is strong and can cause the plant to wither. The last survey should be done one week to 10 days before planting for the plant to have already taken vigor.The pruningis also an opportunity to sort the plants (by size or vigor), to eliminate stunted plants that have no future and to remove the bags where the plant is dead.
Preparation of plants for transport
pruning one week before planting makes it possible to do the last sorting of the plants. A study has shown that in the nursery 20 to 30% of the plants must be eliminated: the most stunted will never give beautiful trees. These plants would normally have already been eliminated during the previous sorts. The plants are watered abundantly before being loaded onto a transport tray. If transport is by cart or tractor trailer, it is not essential to protect the seedlings. On the other hand, in tarpaulin or truck, it is essential to put a tarpaulin to protect the plants from the wind and sun and prevent them from drying out. Transportation will be at cool times, in the evening, the day before or the morning of planting.
Nursery tracking book
In the nursery monitoring log, all the operations performed and the work time must be noted. This makes it possible to estimate the production costs, the success rates and to progressively improve the technique. Note in particular the number of pots filled and put in place per day. For each plate it is necessary to note the species, the dates of sowing, the pretreatments carried out, the dates of germination, the germination rates week by week, the fungicidal and insecticidal treatments, the wedding, the separation, the sorting of the plants and the pruning, as well as the height at the nursery exit date, the ratio seeded plants / seeded pots.