AGRONOMIST NOTEBOOK: Hygiene is a must for high carrot yields Agronomist carrot

Friday October 11 2019
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Cosmas Ngetich harvests his Royal Carrot seeds at Tegat Farm in Elburgon .The farmer sprays his variety three weeks after planting in order to kill the weeds and increase the yields.PHOTO|JOHN NJOROGE|NMG


Carrots can be cooked or be eaten raw. In most parts of Kenya, farmers rely on rain as the primary source of water. Recently, I encountered Maina — a carrot farmer from Nyahururu — who kept lamenting about his small harvest.

The carrots were also deformed while some had started turning green. Because of this, Maina could not find a market for his produce.

He eventually ended up selling the carrots at a throwaway price, incurring heavy losses.

Being a root vegetable, carrot plants require a fine tilth. The farmer should, therefore, prepare the land adequately as the carrots seeds are very tiny. To avoid poor and delayed germination, the seeds should not be deep-sowed. Soil type determines the variety of the carrot to be grown.
Carrots should be planted in deep, loose, sandy soil that does not have hard pans. This will enable the plants to develop deep, long and straight roots.

No manure application

The pH of the soil should be between 6 to 6.5. The soil should also have a sufficient amount of potassium. Raised beds or containers can be used in areas where the soil is compact or rocky.


The choice of the carrot variety to be planted is determined by the root size. Short root carrot varieties, for example, do well in heavy and rocky soils. The crop is ideally grown in areas of full sunlight but can tolerate a moderate amount of shade.

Soils should be fertile and well-drained. While preparing the land, there should be no manure application as manure results in forking of the carrots, making them lose market value.

Forking is also associated with anything that interferes with tap root growth. This includes nematodes, which feed on the growing tip, resulting in the branching of the root. Poorly decomposed organic matter results in hairy roots. This also occurs if too much nitrogen is applied before or after planting.

Heavy rain and poor drainage result in the death of the tap root due to lack of oxygen. This causes the development of side roots.

Earthing up

The soil should, however, be fertile to ensure proper root development. Phosphatic fertiliser should be applied to the soil during planting. The seeds should be two centimetres apart while the soil should be kept moist until germination takes place.

To avoid overcrowding during sowing, the farmer should consider mixing the seeds with sand particles. Where the carrots are too overcrowded, thinning should be done to 5cm apart.
This allows the carrots ample time to develop underground. Earthing up is necessary as exposing carrots to sunlight makes the root turn green, resulting in a bitter taste. Earthing can be done when weeding.
Another problem facing carrot farmers is infestation by the cutworm.

This is the larval stage of the grey night-flying moth. The insect lays eggs on young weeds and plants randomly.

The caterpillar can hatch and remain alive long before the carrots are planted.

Why maintaining field hygiene is crucial

In many cases, the caterpillar is only noticed when damage has already occurred. Field hygiene should thus be maintained.

The land should also be thoroughly ploughed to expose the caterpillars to predators and desiccation by the sun.

Other pests and diseases include aphids and bacterial soft rot. The latter disease makes carrots soft, watery and slimy. The carrots produce a foul smell. This can be controlled by practising crop rotation, burning infected crops, storing the carrots in well ventilated rooms and other practices.
Use certified seeds as these are resistant to the diseases.

Carrots take three to four months to mature. One should not be fooled by the tops, which can be bushy but with a small tap root.

Before harvesting, the farmer should sample the carrots by pulling some from the ground to determine their maturity.

For easier harvesting, the soil should be wet. Harvesting should be done when the roots are soft and juicy. Late harvesting, especially during the rainy season, results in carrots developing cracks.