Carrots are a cool-season root crop that is grown for their edible roots. They require specific soil conditions and management practices to grow properly. Here is a detailed guide on agronomy for carrots that covers land preparation, planting, weed control, irrigation, and more.
Land Preparation
The first step in preparing land for carrots is to plough-disc-role to obtain a fine tilth. Muck soils or loose, friable sandy loam soils are ideal for carrot production. Although heavier soils are not ideal, carrots can be grown on heavy-textured soils under irrigated conditions. Short, blunt types are often grown on heavier soils. Sandy loam soils allow proper growth and development of a long, smooth, straight root. Soils cannot have excessive stones, pebbles, and debris since this can cause forked or misshapen roots. Soils should also be well-drained as carrots will not perform well under water-logged conditions.
Sites should be selected that have loose, friable soils to a depth of 30-35 cm without pebbles. Deep sandy soils can also be used although they may require more frequent irrigation. Drain tiles should be installed on flatwood-type soils that are subject to water-logged conditions. Preparing high beds to avoid wet conditions in these soils is not recommended since under drier circumstances these beds will dry out and cause damage to carrot tops and shoulders.
Proper land preparation should begin by deep-turning soils to bury any litter and debris and breaking soils to a depth of 30-35 cm. Compacted soils or those with tillage pans can benefit from subsoiling to break the compacted areas. If uncorrected, compact soil or tillage pans can result in restriction of root expansion.
It is best to apply lime after deep turning to prevent turning up acid soil after lime application. After turning, mark beds using tractor tracks. Prepare a good seedbed using bed-shaping equipment, it is best to allow the beds to settle slightly before planting. Avoid other tillage practices that can increase soil compaction.
Planting
Seed is sown directly in the lands. Carrots can be broadcast or sown in rows 80 mm-600 mm apart depending on the method used for weed control. Rows 250-350mm apart are common. If herbicides are to be used closer spacing can be used. Where mechanical weed control is to be used twin rows can be used leaving a track row of 600mm. a seed rate of 4-5kg/ha is ideal.
A final plant population of 100-160 plants/m2 is ideal. Overcrowding produces undersized roots. Sow seed 15-20mm deep. Cover the seed with sand and irrigate frequently. Under hot conditions, mulching will enhance germination but the mulch should be removed soon after germination or the seedlings become lanky.
Weed Control
Carrots develop very slowly in the early stages and cannot compete with weeds. On a small scale, a swan neck hoe can be used for weeding. Some hoes are big for the inter-row and may dig too deep. Linuron can be used as a pre-emergence herbicide.
Irrigation
Available water has the same effect as temperature. Low soil moisture content leads to long tapering roots with good color while high soil moisture content results in shorter and thicker roots. Fluctuating water supply combined with high temperature results in deep horizontal depressions in the roots.
Excess moisture following drought can cause corky outgrowths and excessive hairiness on the roots. Root penetration depends on the soil conditions. Feeder roots are found at the top. Towards harvesting withdraw water for two weeks because if roots are lifted in moist.
