Carrots are difficult to germinate and the seed is small making handling difficult also thinning is tedious if required. My method is to encase the seed in small tissue balls, plant under a raised board at adequate spacing. Germination approaches 100 percent.
http://durgan.org/2017/June%202017/7%20June%202017%20Carrots/HTML/ 7 June 2017 Carrots
http://durgan.org/2017/April%202017/25%20Apil%202017%20Carrots/HTML/ 25 April 2017 Carrots.
Carrot seed is quite small and difficult to plant at an appropriate spacing. Thinning small plants is a tedious task. My method is to enclose the seed in a soft tissue ball, which makes planting easy. I only require about 200 so the task is not too onerous. Other seeding methods are to sprinkle through a device similar to a salt shaker also use seed tapes. Both have their handicaps. Planting the ball for a reasonable number is probably the most desirable method. Planting is set at about two inch spacing in a 25 foot row, which is adequate to produce single healthy not intertwined carrots.
http://durgan.org/2017/April%202017/25%20April%202017%20Planting%20Carrots%20Board%20Method/HTML/ 25 April 2017 Planting Carrots Board Method
Carrot seed to obtain good germination and spacing some steps can be taken. Encapsulate the seeds to make them larger and easier to handle, and use the board method to improve germination. Adequate seed spacing at planting means no thinning of very small plants is required. Covering the seeds with a board prevents the seeds from drying out due to hot sun and moderates the soil temperature (Carrots will not germinate above 80F), and from getting moved by heavy rainfall until the plant is established. The board covering is raised with cross pieces so the emerging plant has some vertical growing space before being removed. The board is removed immediately upon the plants emerging. The board method improves germination for most seeds.