Early phosphorus sufficient potassium pomelo tree has high yield

Pomelo, also known as pomelo, branches and leaves are thicker and wider than citrus, yield per mu is high, fertilizer amount is also more, it is the "big food household" in citrus family. Grapefruit production area is mainly in South China, soil is seriously deficient in potassium, potassium and nitrogen fertilizer application amount is roughly the same. Balance fertilization of nitrogen, phosphorus and potassium in pomelo, control of nitrogen, early application of phosphorus and sufficient application of potassium, play an important role in taste and high yield of pomelo products. In recent years, grapefruit cultivation in China has developed rapidly, planting plots are farmland and newly reclaimed slopes. Organic fertilizer and phosphorus and potassium fertilizer should be applied to newly reclaimed slope land, and the yield will be obviously increased after 2~3 years. The annual yield per mu in the main grapefruit producing areas is generally 3500~4500 kg. According to this yield level, the fertilizer application amount per mu is suggested as follows: ① post-fruit fertilizer: compound fertilizer (15%-15%-15%) 75~ 100kg, high-quality organic fertilizer 150~ 250kg or farm manure 2~ 4tons, applied in 2~3 times;② pre-flowering fertilizer: urea 30~ 35kg;③ fruit strengthening fertilizer: urea 25~ 30kg, potassium chloride 35~ 40kg, applied in 1~2 times. The upper limit of fertilizer application was taken for high yield and the lower limit for low yield. There are 5 fertilization stages in pomelo: fertilizer after fruit, fertilizer before shoot, fertilizer for fruit, fertilizer for fruit expansion and fertilizer for fruit growth. 5~6 times for sandy soil and 4~5 times for viscous soil. Grapefruit fertilization frequency is too small, can save labor, but easy to appear de-fertilizer; if the growth is weak, can increase the application of fruit expansion fertilizer. Pomelo slope fertilization, in the crown periphery near the drip line, using circular hole fertilization or furrow fertilization; flat orchard fertilization using strip fertilization. The depth of the ditch is about 30 cm, the fertilizer should be kept about 5 cm away from the root system, the soil should be restored after fertilization, and the roots should be watered in time to avoid injury. Pomelo tree magnesium deficiency magnesium sulfate or potassium magnesium sulfate, calcium deficiency gypsum or lime, 15~20 kg per mu. Boron deficiency often leads to petiole dehiscence and flowering but no fruit bearing. In early growth stage, spraying 0.2% boric acid solution per mu for 2~3 times with an interval of 10~15 days. Pomelo tree pruning and girdling techniques should be done well, please have experienced fruit growers or fruit technicians to ensure fruit tree safety and fertilization results.