Things to consider before starting onion farming
According to Food and Agriculture Organization’s report, half of red onions sold in Kenyan markets are grown in Tanzania. Local farmers are trying their best to address the demand and close the gap, although the demand is always higher than the supply. This demand makes farming onions investment a very attractive commercial investment.
There are two main onions grown in Kenya, bulb onions and spring onions. Of the two types, bulb onions are more popular than the spring ones due to their long shelf life and sweet taste. Prices of onions fluctuate depending on the season and variety planted. The price fluctuation is mainly attributed to the importation of onions from Tanzania, where the cost production is lower. Timing is therefore key if a farmer wishes reap from their produce. The best time is between November to May as onions fetch high prices due to low supply from Tanzania.
The best areas suited for growing onions are Kajiado, Narok, Kieni, Karatina, Oloitoktok, Kakamega, and Naivasha, among others. Onions do well in well-drained fertile soils rich in humus with the pH ranging from 5.8-6.5
The common varieties grown in Kenya include Jambar F1, Islero, Red creole, Red Passion and Red Pinnoy. All the varieties in Kenya prefer warm to hot temperatures, that is 15-30 degrees Celsius.
An acre requires 1-1.5kg of onion seeds depending on the variety and the spacing. The spacing normally affects the size of the bulb onions. Onions can be grown by direct seeding, which requires intensive management or one can decide to first establish a nursery bed. Just like other vegetables planted on nursery bed, site selection is key to proper planning for production of healthy and vigorous growing seedlings. The site should be in a secure environment, near a water source and preferably near the crop production site. It should be raised to a height of about 15cm to encourage drainage, 1m width for easy workability and the length of your own desire depending on the number of seeds to be sowed.
Shallow drills are made 2cm deep and 15cm apart after levelling and seeds sowed singly. This is achieved by mixing sand and onion seeds in a ratio of 3:1.
Cover the nursery bed using agro — nets or dry grass free of weeds, pest and diseases and immediately after sowing, watering should be done twice per week depending with the moisture level. In most cases, the seeds sprout after seven days.
The crop in the nursery should be established for 4-6 weeks and transplanted when pencil size in thickness, 10 to 15cm tall and have 3-5 true leaves.
It’s always wise to do a soil test before planting to know the status of nutrients in the soil, which will guide you on nutrient application for onions production.
A serious farmer should prepare the land to a fine tilth and add well decomposed manure. Depending on the soil test, one can consider using DAP during planting and top-dress using CAN at week four. Frequent scouting for crop nutrition is paramount and mitigation measures should be taken immediately.
To prevent the transplanting shock, do the exercise early morning, late in evening or when the weather is cloudy.
It’s ideal to trim the shoot and root (3 inches for shoots and 0.5 inch for roots) before seedling placement to minimise moisture loss and seedling shock during and after transplanting.
The ideal spacing is 8-10cm between the seedlings and 15cm for inter row distance to allow better bulb development. Spacing is also determined by the variety planted and soil fertility.
Onion production can be done in the greenhouse and open field depending on the location with the latter being more preferred.
Rains or excess watering
Too much rains or excess watering can water log the crop. If the rain in your area is too much, focus on growing the crop during the short rains. You can also raise the beds to ensure the water flows out of the field. Avoid excessive watering of your onions. The best type of irrigation on onions is drip irrigation. Overhead irrigation should be avoided as it causes fungal diseases.
Pests and diseases
Common diseases that affect onions include Downy Mildew, Bacterial Soft Rots, Pink/White Root, Botrytis, and Rusts. Use herbicides to get rid of the diseases. Common pests that attack onions include maggots, thrips, onion flies, red spider mites, nematodes and the leaf miner. Use pesticides from accredited brands to get rid of the pests. Frequent scouting for pest and diseases is important for early detection, prevention and control.
The land should be free of weeds, which compete for nutrients, light and space and harbour pest and diseases. Weeds should be removed occasionally either physically or through the use of herbicides. In one season, there should be at least 2 – 3 weeding sessions.
Once transplanting is done, one should prepare to harvest after 4-5 months depending on the variety. Top leaves will yellow and begin to fall over, an indication they are ready for harvesting, which should coincide with dry and hot weather.
Curing of the onions is done by uprooting every single stem and leaving it to dry after which leaves and roots are cut off with a sharp knife. A good harvest offers 20-25 tonnes per acre depending with the variety.
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