Cannabis requires the most nitrogen, potassium and phosphorus, followed by potassium.

For the yield of 1 ton of hemp stalk per hectare, it requires 15-20 kg of nitrogen, 15-20 kg of K2O and 4-5 kg of P2O5.The results showed that the fresh stems and leaves of hemp contained 0.525% nitrogen, 0.133% phosphorus and 0.415% potassium.Fresh stems contained 0.473% nitrogen, 0.111% phosphorus and 0.341% potassium.Fresh leaves contained 0.858% nitrogen, 0.275% phosphorus and 0.891% potassium.

When marijuana is given sufficient nitrogen, phosphorus and potassium fertilizer;The formation of fibers in the stem is most intense.Nitrogen plays the largest role in the composition of complete fertilizer.In the absence of nitrogen, the effect of phosphorus and potassium fertilizer on fiber formation appears weak.

Therefore, to improve the fiber formation process, early nitrogen application is very important.Application of nitrogen in late stage had little effect on the formation of primary fibers, but increased the formation of secondary fibers.Apply nitrogen too much, fiber becomes coarse, strength decreases, still can cause disease.

Many experimental studies have proved that the combination of nitrogen, phosphorus and potassium is better than the single application of nitrogen fertilizer.The effect of increasing yield is more remarkable when n, p and k are used together.This is because phosphate fertilizer has the effect of improving fiber quality and seed yield, potash fertilizer has the effect of improving fiber yield and quality, and seed oil content, potassium affects fiber quality more than phosphorus, and phosphorus deficiency affects nitrogen absorption.It has been proved that the combination of chemical fertilizer and farm organic fertilizer plays an important role in increasing fiber yield and varieties.

The absorption of nitrogen, phosphorus and potassium in different growth stages of cannabis is different.Hemp needs a lot of nitrogen fertilizer in the whole vegetative growth period before flowering, especially in the first 6-8 weeks when nitrogen absorption is concentrated, but too much nitrogen is unfavorable to fiber content and fiber strength.Cannabis needs a steady supply of phosphate fertilizer throughout the growth period, and the demand for phosphorus continues to increase until flowering, and phosphorus can promote the effective absorption of nitrogen by cannabis.From germination to harvest, hemp's potassium requirements continue to increase, reaching a maximum during the fiber formation period.Potassium fiber quality is more important than phosphorus.

There are differences in the absorption and utilization of nitrogen, phosphorus and potassium in different types of cannabis.Generally, the absorption and utilization of nutrients of early maturing hemp are not balanced, and the absorption of nutrients in the first two months accounts for 3/4, while most of the nutrients are consumed in the short period from bud to blossom.The absorption and utilization of nutrients of late - ripening hemp were more balanced.The absorption of nitrogen and potassium reached a peak 20-25 days after sowing early hemp.The male plant absorbed more nitrogen than the female plant from the seedling stage to the pre-flowering stage.The female plant absorbed more nitrogen than the male plant at the flowering stage.

Some trace elements such as copper, sodium, boron, manganese and zinc have certain effects on hemp growth and fiber quality improvement.Practice has proved that potassium, manganese and magnesium have the greatest influence on hemp yield and fiber development. Manganese, magnesium and potassium 10 magnesium increase production by 27-30%, and potassium and potassium 10 manganese increase production by 15-17%.