（1） Fertility and Nutritional Characteristics

Rapeseed is an oil crop, with three types: cabbage type, radish type, and cabbage type. Cabbage and radish types are often live streamed, while cabbage type seedlings are transplanted. Cabbage type rapeseed has a high yield, with most acres producing oil; 160 kilograms. The growth and development of rapeseed go through seedling stage, moss stage, flowering stage, heading stage, and maturity stage. With sufficient nitrogen, the effective flower bud differentiation period is correspondingly prolonged, laying the foundation for increasing the number of siliques, grains, and grain weight; Timely supply of phosphorus can enhance the stress resistance of rapeseed, promote early maturity and high yield, and increase oil content; Increasing potassium application can alleviate the occurrence of rapeseed stem rot and promote the formation of a large number of stems and branches. The late seedling and moss stages of rapeseed are the peak periods for nutrient absorption and dry matter accumulation. At this time, balanced and timely supply of nutrients such as nitrogen, phosphorus, and potassium is the key to high-quality and high-yield rapeseed.

Rapeseed is a crop of the Brassicaceae family and the Brassica genus, which absorbs more nutrients such as nitrogen, phosphorus, and potassium. Generally, the yield of rapeseed per mu is 100 kilograms, and it needs to absorb nitrogen (N) of 6.8; 7.8 kg, phosphorus (P2O5) 2.4– 2.8 kg, potassium (K2O) 5.5– 7.0 kg, with an average N: P2O5: K2O ratio of 7.3:2.6:6.3, then 1:0.36:0.86. If 150 kilograms of rapeseed are produced per mu, it needs to absorb N— P2O5— K2O has an average of 11— 4— 9 (kilograms). 90% of the rapeseed planting area in China is winter rapeseed grown in the Yangtze River Basin and areas south of the Yellow River, with a growth period of 140 days; 150 days. Other rapeseed varieties have a short growth period and low yield, but the difference in fertilizer requirements is not significant.

（2） Fertilization dosage

Winter rapeseed is a winter crop and often a drought crop with water drought rotation. The soil is prone to phosphorus deficiency, and coupled with low soil temperature during the seedling stage, the phosphorus supply capacity is weak. Therefore, it is important to pay attention to increasing the application of phosphorus fertilizer. Experiments have shown that the appropriate ratio of nitrogen, phosphorus, and potassium fertilizers for rapeseed production is 1:0.6 for N: P2O5: K2O; 0.8∶0.5— 0.6, with an average of 1:0.70:0.55. If 150 kilograms of rapeseed oil are produced per mu, nitrogen fertilizer (N) application is generally required per mu; 17 kilograms, with an average fertilization amount of 16 for N— P2O5— K2O; 11— 9 (kilograms). The amount of fertilizer should also be adjusted appropriately based on the amount of organic fertilizer and the degree of soil nutrient deficiency.

（3） Fertilization method

Base fertilizer: includes 50% of the total nitrogen fertilizer, as well as all phosphorus, potassium fertilizer, and farm manure. The amount of farmyard manure used depends on the quality of the fertilizer, usually applied at a rate of 3 to 3 per mu; 5 tons. Insufficient basal fertilizer results in weak and weak seedlings, and even with a large amount of topdressing, it is difficult to make up for it. Topdressing: divided into wax fertilizer (late seedling stage topdressing) and moss fertilizer (mid bolting stage), each accounting for about 25% of the total nitrogen fertilizer application. If the growth of rapeseed is weak, it can be fertilized in the early stage of bolting to avoid premature aging; Strong growth can occur in the late stage of bolting, with moss height of 30‐ Apply it after 50 centimeters to prevent excessive growth. The flowering period should be determined based on the growth of rapeseed, and if fertilization is needed, 1% urea or potassium dihydrogen phosphate solution can be sprayed during the flowering and pod setting period; 70 kilograms, with good results.

Rapeseed is a crop that requires a high amount of boron and is sensitive to boron. It is prone to occur in boron deficient soils; Flowers but not seeds "refers to the phenomenon of rapeseed continuously blooming without setting seeds, also known as atrophy and non fruiting disease. Boron fertilizer can be used for foliar spraying or soil application. Foliar spraying can save on usage, just spray once each during the late seedling stage and bolting stage. In some areas, rapeseed often suffers from sulfur and zinc deficiency, which should also be taken seriously. Whether the soil lacks trace elements, the application concentration and dosage can refer to the following information:

The content of trace elements in soil below the following levels (mg/kg) is considered deficient: calcium 600— 800, Magnesium 60‐ 80. Sulfur 10‐ 16. Zinc 1‐ 1.5 Boron 0.25‐ 0.5. Manganese 4‐ 7. Molybdenum 0.1‐ 0.15, Copper 0.1‐ 0.2. Iron 4‐ 5. Magnesium, sulfur, and calcium are commonly used as magnesium sulfate, sulfur, gypsum, or lime, with a soil application rate of 10 to 100 per mu; 15 kilograms. Manganese, zinc, and boron are commonly used as manganese sulfate, zinc sulfate, and borax, with soil application rates of approximately 2 kilograms, 1 kilogram, and 0.5 kilograms per mu, respectively. Spray concentration: Medium element 0.5‐ 1%, trace elements 0.1‐ 0.3% is suitable, spray solution per mu for 50‐ 75 kilograms.

2. Symptoms of nutrient deficiency

Rapeseed nitrogen deficiency: The plant growth is not vigorous, short, and weak. Branches are short and small, with larger branches at the top and smaller branches at the bottom of the entire plant. The lower leaves of cabbage type are yellow green, while the lower leaves of cabbage type are red purple. Leaves wither and fall off prematurely. The roots are slender, with few branching roots, and white in color.
Rapeseed phosphorus deficiency: slow leaf emergence, small leaves, dark green in color. The lower old leaf stem and petiole are purple red in color. Slow root development. Poor stress resistance and abnormal early puberty. The seeds are not full, the yield decreases, and the oil yield is low.
Rapeseed potassium deficiency: The plant is short and stunted. At first, the leaves are dark green in color, and the leaf edges begin to curl downwards, especially in dry and hot weather. In the future, when potassium deficiency is severe, white yellow spots will appear on the outer edge of the leaves, and old leaves will dry up before maturity. The pods are thin and the yield decreases.
Rapeseed lacks calcium: the plant is short and stunted. The edges of the lower leaves are scorched and withered, the top flowers fall off, the growth points become sticky, and in severe cases, ulceration occurs.
Rapeseed magnesium deficiency: There are purple red patches on the middle and lower leaves, with yellow purple and green purple flower spots on the leaves.
Rapeseed sulfur deficiency: The plant is short, the leaves are light green, and the back of the leaves turns red. The leaves are upright or curled, the growth period is delayed, and the flowers are small and few.
Rapeseed boron deficiency: slow plant growth and dwarfism. The stem is excessively long and thick, and the wood is damaged. When there is mild boron deficiency, blue purple spots appear between the leaf veins, and purple spots develop at the edges of old leaves. Abnormal buds and withered flowers appear. Continuous flowering at the top, prolonged flowering period, few siliques, and lack of fruiting, commonly known as“ Flower without substance syndrome.