How to choose the right seed fertilizer for autumn sowing? These key points you need to master

Seed fertilizer is fertilizer applied locally near the seeds or seedlings when sowing, soaking seeds, or sowing and transplanting. It can supplement the shortage of base fertilizer, supply nutrients for the early growth of crops, and help cultivate strong seedlings. However, some chemical fertilizers have toxic effects on seeds and seedlings, so attention should be paid to the suitability and taboos of seed fertilizer selection.

I. Chemical fertilizers suitable as seed fertilizer

Generally, quick-acting chemical fertilizers or fully decomposed farmyard manure are used as seed fertilizer. The chemical fertilizers that can be used as seed fertilizer include the following:

1. Ammonium sulfate. Abbreviated as ammonium sulfate, when used as seed fertilizer, contact with seeds should be avoided. When applying, ensure that the seeds and ammonium sulfate remain dry, with a dosage of 2.5 kg per mu, and sow immediately after mixing, not allowing it to sit for long.

2. Calcium superphosphate. Abbreviated as ordinary calcium, when used as seed fertilizer it can reduce the fixation of phosphorus by soil and help seedlings absorb phosphorus. Before use, crush and sieve it first; contact with seeds can burn seedlings. Because ordinary calcium contains more than 5% free sulfuric acid and phosphoric acid, it has certain harm to seed germination and seedling growth. It is best to mix it with farmyard manure to avoid toxicity. The dosage is preferably 5-10 kg.

3. Triple superphosphate. Abbreviated as heavy calcium, when used as seed fertilizer, the dosage per mu is preferably 2.5-5 kg. Because heavy calcium does not contain calcium sulfate, its application effect on sulfur-loving crops is inferior to ordinary calcium. In addition, its effect when applied to alkaline soil is also inferior to ordinary calcium.

II. Chemical fertilizers not suitable as seed fertilizer

1. Fertilizers with volatility and corrosiveness. Ammonia water, ammonium bicarbonate, etc., have strong volatility and easily damage seeds or seedlings. To use them as seed fertilizer, ammonium bicarbonate and ammonia water can be applied below the sowing furrow or hole and covered with soil, which can avoid toxicity.

2. Chemical fertilizers with direct toxic effects on seeds. During the production of urea, a small amount of biuret is often produced. When its content exceeds 20%, it will cause toxicity to seeds and seedlings. In addition, urea molecules with high nitrogen content will also penetrate into the protein molecular structure of seeds and seedlings, causing protein denaturation and affecting seed germination. Therefore, urea cannot be used as seed fertilizer.

3. Strongly alkaline chemical fertilizers. Strongly alkaline fertilizers such as steel slag phosphate fertilizer and kiln ash potassium fertilizer easily burn seedlings, so they are not suitable as seed fertilizer. For example, kiln ash potassium fertilizer contains more calcium and has strong hygroscopicity. After absorbing water, it becomes slaked lime and releases a large amount of heat, easily burning seeds and young roots. When used as seed fertilizer, an appropriate amount of chemical fertilizer must be mixed with organic fertilizer, applied into the sowing furrow or hole, and then sown and covered with soil to prevent fertilizer damage.

4. Fertilizers containing harmful ions. Chemical fertilizers such as ammonium chloride and potassium chloride contain large amounts of harmful chloride ions. After being applied to soil, they produce water-soluble nitrogen compounds that burn seeds and seedlings. Some compound fertilizers are produced using ammonium chloride and potassium chloride as raw materials. When choosing compound fertilizers as seed fertilizer, it is not advisable to choose compound fertilizers containing chloride ions.

Jia Youjiang, Agricultural Bureau of Juancheng County, Shandong Province