Wheat fertilization has its particularities: pay attention to less phosphorus and more potassium

Applying excessive phosphorus to wheat first of all increases costs. This year diammonium phosphate is quite expensive, with the retail price of 64% exceeding 3900 yuan/ton. Phosphorus is essential, but there is no need for excess. Empirical data shows that using 40-50 kg of a ternary compound fertilizer containing 15%-20% pure phosphorus per mu as a base fertilizer generally prevents phosphorus deficiency.

Applying excessive phosphorus causes soil compaction, fixation of certain secondary and trace elements, and severe deficiency symptoms. Because phosphorus that wheat cannot absorb will accumulate in the soil, and its phosphate ions combine with cations such as calcium and magnesium in the soil to form sparingly soluble phosphates, which not only wastes phosphate fertilizer but also destroys the soil's aggregate structure, causing soil compaction. Therefore, do not over-apply phosphate fertilizer (such as diammonium phosphate) in the base fertilizer.

When applying phosphate fertilizer, choose a ternary compound fertilizer with a relatively high phosphorus content for the base fertilizer, and apply the phosphorus in full in one application. For example, in the winter wheat areas of Shandong and Hebei, formulations such as 20-20-5, 20-20-7, 20-20-8, and 20-20-10 can be chosen at 40-50 kg/mu; in the winter wheat areas of Henan, northern Jiangsu, and northern Anhui, formulations such as 22-14-10, 25-13-10, 27-12-10, and 27-13-10 can be chosen at 40-50 kg/mu.

When using diammonium phosphate and low-nitrogen high-phosphorus compound fertilizer as the base fertilizer, in addition to ensuring a per-mu application rate of 30-40 kg, add 10 kg of urea per mu to prevent yellowing of seedlings caused by competition for nitrogen between straw decomposition and young seedlings.

Since 2008, the price of potassium fertilizer has soared, leading to less and less potassium being applied in agricultural production. This situation has lasted for nearly 4 years, and in the past two years, lodging of summer corn and winter wheat in North China has shown an increasing trend, which to a certain extent shows that potassium supplementation has become crucial.

Straw returned to the field can provide part of the potassium fertilizer. If 40-50 kg of ternary compound fertilizer is used per mu as the base fertilizer, there is no need to choose formulations with particularly high potassium content such as 19-19-19 and 18-18-18. First, this year fertilizers with high potassium content are particularly expensive, increasing costs; second, excessive potassium fertilizer cannot be used up and is too wasteful.

It is recommended to choose a high-nitrogen, high-phosphorus, medium-potassium ternary compound fertilizer with a potassium content of about 7% as the base fertilizer, at 40-50 kg/mu, such as: 20-20-7, 20-20-8, 20-20-10, etc. During the greening stage after the New Year, choose a nitrogen-potassium binary compound fertilizer with a potassium content of 5%-10% as a topdressing, at 20-30 kg/mu, such as 30-0-5, 30-0-10, etc. Applying potassium fertilizer in two split applications can also improve potassium use efficiency and ensure disease resistance, lodging resistance, and high yield.