Mulching in production of seedlings
Mr Issack Mohamed Adan (in white), an onion grower in Mandera county on August 23. Weeding the onion bed prevents competition for nutrients and space.
In our previous article, we looked at sowing of seeds for onion production. Desmond has started carrying out management practices in the nursery bed.
Mulch needs to be added to the nursery bed as soon as the seeds are sown.
Mulching is the covering a bed with plants or other materials, such as seedless grass, straw and shade or mulching net to preserve moisture, inhibit weed growth, lessen erosion and enhance soil conditions.
It facilitates quick and effective soil temperature regulation, which aids in high germination rates, provides protection of seeds from birds and other pests and cushions seeds from direct sun heat.
The farmer should gather adequate mulching materials for the onion nursery and remove foreign materials by cleaning the material.
If the mulch has been used previously, one should disinfect it. Mulching materials 3-5cm thick should be applied gently and evenly to the bed.
Watering should be done gently and evenly, depending on the soil moisture and prevailing weather conditions.
In most cases, seeds germinate seven to eight days.
Once seedlings have emerged, Desmond will take the mulch off. This is done when 70 per cent of seeds have emerged. Delayed mulch removal causes seedlings’ stems to grow longer in their search for light, resulting in stem breaks.
The mulch should be removed when the weather is cool. To prevent damage to seedlings, caution should be taken when removing the mulch.
There should be watering after the mulch has been removed. Always use clean water.
The mulch removed should be placed far from the bed to avoid pests and diseases.
After removing the mulch, ensure the nursery has a shade net to shield seedlings from severe weather conditions. Farmers occasionally build a shelter out of dry grass that is about 1-2 metres high.
To keep shade materials from being carried away by the wind, one should tie threads across them or erect rafters at the top.
Weeds start to grow as the seedlings emerge. Herbicides should be avoided around seedlings in the nursery since they are still vulnerable.
Weed the bed to prevent competition for nutrients and space. Take care not to uproot or harm the seedlings when weeding.
To prevent weeds from serving as breeding grounds for pests, dispose of them of properly.
One of the diseases that can affect onion seedlings is damping off.
Depending on the condition of the seedlings, Calcium Ammonium Nitrate (CAN) may be used in week three to promote vegetative development.
In our next article, we shall look at the pricking out and hardening off and develop a nursery management plan for Desmond.
