（1） Fertility and Nutritional Characteristics

The nutritional growth stages of winter wheat include emergence, tillering, overwintering, greening, standing up, and jointing; The reproductive growth stages include booting, heading, flowering, filling, and maturity. The yield of spring wheat is relatively low, with a short growth period of only 100%; 120 days. The main goal of fertilization for wheat from emergence to jointing is to strengthen root growth, promote tillering, and dry matter formation; Fertilization from jointing to heading is to promote stem and leaf growth, effective tillering, and ear enlargement; From heading to maturity, the main focus is on increasing the number of grains, grain weight, and protein content. After winter wheat turns green, the rate of nutrient absorption increases, and the period from jointing to heading is the fastest period for absorbing and accumulating dry matter; The peak of nitrogen absorption occurs from jointing to booting, and after flowering, the absorption rate of nutrients gradually decreases. Winter wheat is a overwintering crop, and the seedling stage is the critical period for phosphorus nutrition. It is particularly important to apply sufficient phosphorus fertilizer to the base fertilizer. Due to weak root systems during the seedling stage, encountering drought and severe cold, the soil's phosphorus supply and crop absorption capacity significantly decrease, affecting the greening and tillering of wheat seedlings. Further application of phosphorus fertilizer is also difficult to remedy.

Generally, for every 100 kilograms of wheat grains formed, 2.6-3.0 kilograms of nitrogen (N), 1-1.4 kilograms of phosphorus (P2O5), and 2-2.6 kilograms of potassium (K2O) need to be absorbed. The average ratio of N: P2O5: K2O is 1:0.4:0.8. If the yield of wheat grains per mu is 500 kilograms, the average absorption of N-P2O5-K2O is 14-6-12 kilograms. It can be seen that under the same increase in yield, wheat requires significantly more nitrogen than rice. The nutrients in wheat plants, including nitrogen and phosphorus, are mainly concentrated in the seeds, accounting for about 76% and 82% of the total, respectively; Potassium is mainly concentrated in the stems and leaves, accounting for about 78% of the total. The proportion of NPK absorbed by winter wheat and spring wheat is very similar.

（2） Fertilization amount

The main wheat producing areas in China are in the north, where both winter and spring wheat are grown. Most soils in the north are alkaline, with abundant potassium and phosphorus deficiency (soil available P content less than 10mg/kg), requiring 4-8 kilograms of phosphorus fertilizer (P2O5) per acre. A large number of experiments have shown that the optimal nutrient ratio for applying chemical fertilizers to winter wheat is a ratio of N: P2O5: K2O of 1:0.5-0.6:0.2-0.3, with an average of 1:0.55:0.25. If the yield of wheat grains per mu is 500 kilograms, a nitrogen fertilizer (N) of 15-17 kilograms is required, and the average fertilization amount of N-P2O5-K2O is 16-9-4 kilograms; The optimal ratio of N: P2O5: K2O for spring wheat is 1:0.35-0.45:0.35-0.45, with an average of 1:0.40:0.40. If the yield of wheat grains is 300 kilograms per mu, 8-10 kilograms of nitrogen fertilizer (N) are required, with an average fertilizer application rate of 9-4-4 kilograms. At present, the seasonal utilization rate of fertilizers in China is roughly as follows: N30% -40%, P2O510%-20%，K2O50%-60%。 After deducting the fertilizer utilization rate, fertilization can meet the NPK nutrient requirements of crops in different soils.

（3） Fertilization technology

1. Base fertilizer: Similar to rice, wheat mainly uses base fertilizer. Low yield fields with a wheat yield of less than 300 kilograms per mu or plots lacking irrigation conditions often use one-time application of sufficient base fertilizer and no longer apply topdressing, which is called“ The "one bombardment" fertilization method.

2. Topdressing: For high-yield wheat fields or sandy loam soils with poor fertilizer retention capacity, generally 30% -40% of nitrogen should be left as topdressing to prevent denitrification in the later stage, and the remaining fertilizer should be used as base fertilizer. Topdressing is often carried out during the tillering or jointing stage, and it is difficult to apply deep soil cover to densely planted wheat. Therefore, watering immediately after applying fertilizer can reduce the loss of nitrogen fertilizer volatilization. Sandy loam soil is prone to water and fertilizer leakage, so the amount of fertilizer applied each time should be less and the number of times should be more; Eat less and eat more. Wheat specific fertilizer used as topdressing should be applied early for good phosphorus effect; If urea is used as topdressing, the proportion of nitrogen in the specialized fertilizer formula should be reduced accordingly. Wheat is prone to manganese deficiency, and soil available manganese below 7mg/kg is considered manganese deficiency. 50-70 kg of 0.1-0.3% manganese sulfate solution can be used per mu for foliar spraying, which has good economic benefits. The soil in the north is alkaline, with more dry land, less rainfall, and phosphorus deficiency. Therefore, more acidic phosphorus fertilizers and nitrate nitrogen fertilizers produced by acid method can be used, and less alkaline phosphorus fertilizers produced by thermal method can be used, which is beneficial for improving fertilizer efficiency and soil improvement.



2. Symptoms of nutrient deficiency

（1） Wheat nitrogen deficiency: The plant is short, the tiller is reduced, and the leaves are small and pale yellow in color.
（2） Wheat phosphorus deficiency: reduced tillering, dark green leaves, dull or purple color, delayed maturity, and incomplete grains.
（3） Wheat potassium deficiency: slow plant growth, poor mechanical tissue development, burnt and prematurely yellowed edges of lower leaves, weak and prone to lodging stems.
（4） Wheat sulfur deficiency: yellowing of leaves, usually more pronounced in young leaves.
（5） Wheat calcium deficiency: Leaves turn gray, new leaves turn white, and then the leaf tips wither.
（6） Wheat magnesium deficiency: The plant is short and often exhibits chlorosis, usually starting with yellowing between the veins of old leaves.
（7） Iron deficiency in wheat: yellowing of the intervein tissue with distinct stripes.
（8） Wheat manganese deficiency: The leaves are slender with irregular spots, and the spots on old leaves are gray, light yellow, or brown.
（9） Wheat boron deficiency: Leaves turn white, curled, and shrink into wavy shapes.
（10） Wheat copper deficiency: Leaves become needle shaped and curled.