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Shade is most easily obtained by selecting a site where existing trees cast a light shade over most of the nursery beds and provide shelter from heavy rain and winds for young seedlings and cuttings. If such a site is not available, trees may be planted, preferably of a leguminous type, and temporary shade provided by thatched mats or screens which can be placed over the beds and containers.
A shelter which is proof against excessive sun and rain is also required as a working area and in which young seedlings can be kept under close observation until they can be placed in more exposed surroundings.
The benches of a plant house should extend beyond the eaves so that boxes or containers of young plants can gradually be given more exposure to the sunlight but can also be rapidly pulled back into shelter during rain.
Watering should be regular and is best applied with a watering can fitted with a fine rose or sprinkler. Recently transplanted seedlings and rooted cuttings may require several applications of water per day during hot weather.
Containers: The use of plastic (polyethylene) pots and containers is now common practice, since traditional containers for plants are expensive. The size which is most suited to the young plant should be selected when these containers are used and, in general, a sandy, well-drained compost should be used to prevent waterlogging. Containers which are being re-used should be washed to prevent the spread of harmful soil organisms.
Composts for nursery work: As a general rule, mixtures which are high in organic material should be mixed for all nursery operations but, for composts used for rooting cuttings and raising seedlings, extra coarse sand will normally be required to promote aeration and good drainage.
Sterilisation of potting and other composts used in the nursery is essential if a high standard of garden hygiene is to are obtained. Chemicals such as formalin (formaldehyde) are often available but satisfactory results are obtained by steaming or baking the soil to kill harmful bacteria, nematodes and other soil pests and diseases.
Heating to a temperature of 80–100° C for a period of about two hours is generally adequate.
The simplest method of sterilising small quantities of soil is by placing the mixture on a sheet of galvanised iron and heating it from a fire below the sheet; the soil should be turned at regular intervals and water added to produce steam within the spaces between the soil particles. The soil should not be used until it has properly Cooled.
Cultivations
For small, intensively cultivated areas, operations such as weeding, fertiliser application and irrigation are carried out by hand since the crops are usually on small plots or beds and are closely planted.
Weeding: An intermediate implement is the hand-pushed weeder. This is an extremely useful implement for use in row crops or on fairly long raised beds since the operator has a close control over the position of the L-shaped blades which cut the weed growth at the soil surface. When fitted with cultivator tines, this implement is also very useful for disturbing small weeds so that they can be desiccated by exposure to the sun.
On a more extensive scale, some level of mechanisation may be needed if the operations are to be carried out at the most suitable period of crop growth.
Implements for weeding which are suitable for tractor attachment have been discussed, most of these are only suitable for use with relatively low growing crops in rows spaced at a standard width, giving access to tractors without damaging the crops.
For small, intensively cultivated areas, operations such as weeding, fertiliser application and irrigation are carried out by hand since the crops are usually on small plots or beds and are closely planted.
Weeding: An intermediate implement is the hand-pushed weeder. This is an extremely useful implement for use in row crops or on fairly long raised beds since the operator has a close control over the position of the L-shaped blades which cut the weed growth at the soil surface. When fitted with cultivator tines, this implement is also very useful for disturbing small weeds so that they can be desiccated by exposure to the sun.
On a more extensive scale, some level of mechanisation may be needed if the operations are to be carried out at the most suitable period of crop growth.
Implements for weeding which are suitable for tractor attachment have been discussed, most of these are only suitable for use with relatively low growing crops in rows spaced at a standard width, giving access to tractors without damaging the crops.
Fertiliser application: Hand methods of application are generally adequate for small scale operations, the fertiliser being either mixed with the surface soil before sowing, or placed in bands along the rows or applied in a circle around the base of individual plants.
Intermediate types of fertiliser drill have been referred to under the heading of hand and animal-drawn equipment. These are used with crops planted in rows and many seed drills can either have attachments added for fertiliser application or be converted for using as a fertiliser drill only. For larger farms, a range of tractor-mounted or trailed fertiliser and combine drills is available and these have been.
Irrigation: On small farms and gardens, water is applied to growing crops by watering can but small hand are also available for lifting and distributing water to fairly limited heights. Hand pumps are only able to operate effectively from streams or shallow wells and, for larger holdings or farms, some form of irrigation pump is required, with distribution pipes and sprinklers. These are somewhat expensive to purchase but, when used for high value crops, the outlay can be regained over a relatively short period.
Staking: Staking is an operation which is mainly confined to yams grown in the savanna areas of West Africa. Some
yam species grow to a height of 3-4 m and the dense mass of stems and foliage produced require the support of large, heavy stakes, preferably ones which are resistant to attack from termites. The stakes are placed in position before the young stems are more than 30-40 cm long so that they can be trained up the stakes and tied in position as they develop.
Some vegetable crops, particularly the climbing forms of legumes, also require support and this is normally provided by inserting stakes, up to 3 m in length, alongside each seedling. Beans are often grown in double rows so that opposite stakes in these rows can be tied together at about two-thirds of their length. Cross stakes, laid horizontally across these ties, are added to give rigidity to the supports. Other vegetable crops are supported on a smaller fence, trellis, or flat table shaped structures.