Carrot is a semi-hardy vegetable, with similar temperature requirements as radish. High temperature is not conducive to root expansion and coloring, and root expansion and coloring are not good when the soil temperature is below 12℃. When the carrot plant reaches a certain size and encounters a low temperature below 10℃, flower bud differentiation will occur. In the high temperature and long sunlight plant flowering, lack of light leaves narrow and petiole slender, yield and quality decline. Prefer sandy loam soil, suitable for pH5-8, soil moisture content is maintained at 60%-80% is appropriate. Too much water, excessive above-ground growth, unfavorable root expansion, and even prone to root rot.
B. Fertilizer requirements of carrot growth and development process
1. The early stage of carrot fertility is slow
In the middle and late stages, when the root system starts to expand, the growth increases rapidly and the nutrient uptake also increases with the increase of fertility.
2. In the two months after sowing
Its uptake of all elements is modest and increases significantly as the roots expand. Uptake was highest for potassium, followed by nitrogen, calcium, phosphorus and magnesium, in decreasing order.
3. Carrots at the time of harvest
Potassium was the most in the leaves, followed by nitrogen, calcium and magnesium, with little phosphorus. While in the roots potassium and nitrogen were the most, followed by phosphorus, calcium and magnesium.
4. Nitrogen requirements of carrots
It is necessary to chase nitrogen fertilizer mainly in the early stage, 30-50 days after sowing, although it is appropriate. If there is a lack of nitrogen in this period, the diameter of the roots will decrease significantly and the fleshy roots will expand poorly.
5. The effect of different forms of nitrogen on the growth of carrot
For example, in a test on saline sandy loam soil, the application of nitrate nitrogen or nitrate nitrogen mixed with ammonia nitrogen resulted in better growth and development than ammonia nitrogen alone. Ammonia N alone is prone to yellowing of leaves, stagnant growth, poor root expansion and increased deformed roots.
6. Phosphorus uptake by carrots
When the effective phosphorus content in the soil is low, the effect of additional phosphorus fertilizer is obvious. As the amount of fertilizer increases, the yield also has a tendency to increase. When the effective phosphorus content is higher than 200 ppm, the application of phosphorus fertilizer does not increase the effect of yield, and may even lead to yield reduction. For calcareous soils where phosphorus absorption coefficient is relatively large, applying more phosphorus fertilizer as base fertilizer is beneficial to early plant growth and later root expansion.
7. Effect of potassium on carrots
The application of potassium fertilizer should be intensified when the replaceable potassium in the soil is below 150-200 ppm. Especially during the fleshy root expansion period, potassium fertilizer needs to be applied retrospectively. It is mainly to make the fleshy roots expand.
C. Technical points of fertilization for carrot
(1) Base fertilizer
Carrot roots are deep in the soil, suitable for fertile and loose sandy loam soil. Before sowing, you should plow deeply and apply sufficient base fertilizer. Apply 2,000-2,500 kilograms of well-rotted stable manure and human urine, 15-20 kilograms of calcium superphosphate, and 100-150 kilograms of grass ashes per mu.
(2) Chemical fertilizer
Available ammonium sulfate 20 kg, calcium superphosphate 30-40 kg, potassium sulfate 30-35 kg per mu.
(3) Method of fertilization
There are two kinds of withdrawal and furrow application, both should be mixed with soil. Fertilizer application has a greater impact on the shape of fleshy roots, the proportion of deformed roots increases significantly when the amount of chemical fertilizer and organic fertilizer less. Increase the application of well-rotted organic fertilizer as a base fertilizer, can reduce the formation of deformed fleshy roots. If the application of unripe organic fertilizer, easy to increase the deformed roots.
(4) Follow-up fertilizer
In addition to the base fertilizer, carrots should be fertilized 2-3 times.
(5) First fertilization
It is 20-25 days after seedling emergence, after 3-4 real leaves are produced. Apply 5-6 kg of sulfate and 3-4 kg of potash per mu.
(6) Second fertilization
Carrots are carried out after the seedlings are set, and each mu it can be used 7-8 kg of ammonium sulfate and 4-5 kg of potash.
(7) The third fertilizer
At the peak of root expansion, the amount of fertilizer used is the same as the third fertilizer.
(8) The type of fertilizer application
In addition to chemical fertilizers, you can also use well-rotted human urine, 1000-2000 kg per mu.
(9) The method of fertilization
It can poured in with water, or humanure and urine can splashed with water. Avoid excessive fertilization in the late growth stage, otherwise it will easily cause root splitting and is not good for storage.
(10) Fertilization standard of carrot
To produce 1000 kg of carrots, 7.5 kg of nitrogen, 3.8 kg of phosphorus and 17 kg of potassium are required.
D. Carrot fertilization techniques
① Characteristics of carrot fertilizer requirements
Carrots absorb the most potassium throughout the growth period, followed by nitrogen, calcium and phosphorus. The nitrogen, phosphorus and potassium absorption ratio is nitrogen (N): phosphorus (P25): potassium (K20) = 3:l:5. Carrots are a vegetable that requires a lot of fertilizer, producing 10,000 pounds of carrots per mu, absorbing 16 kilograms of pure nitrogen, 6.5 kilograms of phosphorus and 25 kilograms of potassium.
②Carrot fertilizer requirements
The amount of nutrients required by carrots varies greatly at different stages of growth and development. In the seedling stage, it absorbs very little fertilizer, and in the leaf growth stage, it absorbs significantly more fertilizer than in the seedling stage. Nutrient uptake increases rapidly during the fleshy root growth period, i.e. from the time of shoulder exposure. Especially in the 10-15 days before harvest, the uptake of nitrogen, phosphorus and potassium can account for 46%, 55% and 50% of the total uptake respectively.
③Recommended fertilizer varieties
The same base fertilizer can choose compound fertilizer 18-12-20, 16-12-20, 18-12-18, 19-19-19, 17-17-17. However, the follow-up fertilizer can choose compound fertilizer 34-0-16, and it is recommended to apply chemical fertilizer mainly with nitrogen and potassium.
④High quality and high yielding carrot land selection
Carrot fleshy roots are deep in the soil, so choose a fertile, soft sandy loam soil.
⑤ Fertilization measures
Apply well-rotted organic fertilizer as base fertilizer, which can reduce the formation of deformed fleshy roots, and deep plowing and fine harrowing after fertilization.
Apply sufficient chemical fertilizer before plowing, together with organic fertilizer about 50 kg per mu of high concentration chemical fertilizer, 18-12-20 and 16-12-20 are preferred.
⑦Timely chasing fertilizer
In the leaf vigorous period mu chase 34-0-16,10-15 kg, dew shoulder period mu chase 34-0-16 fertilizer 10 kg + potassium sulfate 10 kg.
⑧ Carrot deficiency disease vol.
Nitrogen deficiency (N): The whole leaf color is light green and turns yellow from the old leaves. Phosphorus (P) deficiency: basically the same as N deficiency, leaves are dark and lusterless, and growth is weak. Potassium deficiency (K): yellowing from the leaf edge of the old leaves. At the same time, leaf rolls turn brown and die.
E. Radish boron application can increase yield
Therefore, practice has proved that the radish increased the application of tonic fertilizer, yield can increased by 20%-30%, and the flesh is tender and not hollow.
F. Application of boron fertilizer method
Firstly, 300g of 17% boric acid or 500g of 11% borax is used in mu, followed by mixing it into 5-10kg of dry fine soil. Mix it well and then sieve it, and then apply it as base fertilizer into the seed furrow or seed hole. You can also mix radish seeds into the dry fine soil mixed with boron fertilizer. Finally, it is well mixed and spread into the seed furrows and seed holes.
Mix 3-5 kg of fine soil with water and boron fertilizer at a dosage of 300 g of tonic acid or 500 g of archival sand per mu, stir together into a thin paste, and then pour in the radish seeds and some dry fine soil. Rub the soil containing boron fertilizer by hand to make the seed coat stick to the surface of the seeds, and use it for sowing when the seeds can separated from each other.
G. Leaf spraying
From the time the fleshy roots of radish start to expand until the first harvest can marketed, use 80-100 grams of boric acid or 120-150 grams of borax (if boric acid is used, it should dissolved in boiling water first) to 50-60 kilograms of water per mu each time. Foliar fertilizer is prepared and sprayed in the evening on a sunny day, once every 15 days, three times in a row. Whether the boron fertilizer as a base fertilizer, seed mix or foliar fertilizer, the field soil moisture content should be mastered at 20%-30%. Soil dryness affects the effect of fertilizer, so such as a long period of dry weather shouldirrigated, using furrow irrigation. If there is a long period of rain or heavy rainstorm, drainage should be timely to reduce stains, especially the seedling field can not be waterlogged.