What techniques are needed for scientific fertilization of corn?
1. Principles. In fertilization, one should master the combined application of nitrogen, phosphorus, potassium and trace elements, balanced fertilization, deep application of fertilizer, topdressing in stages, and combining water and fertilizer to improve fertilizer efficiency. As for the amount of fertilizer applied, it should be comprehensively considered based on various factors such as the fertilizer absorption pattern of corn, yield level, soil fertilizer supply capacity, fertilizer nutrient content and utilization rate.
2. Base fertilizer. Fertilizer applied before sowing is called base fertilizer. Generally, organic fertilizer, compound fertilizer, or part of the nitrogen fertilizer and potassium fertilizer and micro-fertilizer are mixed and applied in concentrated furrows. If there is no time to apply it, it can be applied all at once as seedling fertilizer.
3. Seed fertilizer. When sowing, the fertilizer applied beside the seeds or together with the seeds is seed fertilizer. It can meet the nutrient needs of corn in the early growth stage and has the effect of promoting root development and making seedlings grow robustly. Generally, 3 kg of diammonium phosphate or compound fertilizer and urea is used per mu, and it should be applied in bands, with the seed fertilizer separated to prevent damage to the seedlings.
4. Topdressing. Fertilizer applied during the corn growth period is topdressing. The timing, frequency and amount of topdressing should be determined comprehensively based on the fertilizer absorption pattern of corn, yield level, geographical foundation, and the peak demand period. At this time, if the nutrient supply is insufficient, flower and fruit drop will occur. Malnutrition will also affect the normal development of floral organs and fruits, such as small pollen and slender, uneven styles, resulting in failure of normal pollination and then shedding.
2. Measures to prevent tomato flower and fruit drop. To prevent tomato flower and fruit drop, on the basis of timely sowing, cultivating strong seedlings, reasonable dense planting, scientific fertilization, and enhancing the plant's stress resistance, the following work should be done in a targeted manner. (1) Improve the temperature and humidity conditions during the tomato flowering and fruiting period, and determine the amount of fertilization based on comprehensive consideration of the situation.
1. Topdressing timing and effects. (1) Seedling fertilizer: generally applied after seedling thinning and before jointing, and the seedling-promoting fertilizer and jointing fertilizer can be combined into one application. It has the effects of promoting roots, strengthening seedlings, promoting leaves and strengthening stems, and lays a good foundation for more and larger seeds. (2) Seed fertilizer: applied at the large trumpet stage of corn. This period has the greatest fertilizer demand and is the key period determining seed size and grain number. It can promote larger seeds and more grains. (3) Grain fertilizer: generally applied at the tasseling and flowering stage. It can ensure sufficient supply of inorganic nutrients, prolong the functional period of green leaves, increase the accumulation of photosynthetic products, and promote more grains and heavier grains to obtain high yield.
2. Topdressing by classification. (1) High-yield fields: with good soil fertility foundation and a large amount of topdressing, it is best to adopt the three-application topdressing method of light seedling fertilizer, heavy seed fertilizer, and supplementary grain fertilizer. The amount of seedling-stage topdressing accounts for about 30% of the total topdressing amount, seed fertilizer accounts for 50%, and grain fertilizer accounts for 20%. (2) Medium-yield fields: with relatively good soil fertility and more topdressing, it is suitable to adopt the two-application topdressing method of applying sufficient seedling fertilizer and heavy seed fertilizer. Seedling fertilizer accounts for about 40% of the total topdressing amount, and seed fertilizer accounts for about 60%. (3) Low-yield fields: with poor soil fertility, topdressing can adopt the method of heavy seedling fertilizer and light seed fertilizer. Seedling fertilizer accounts for about 60%, and seed fertilizer accounts for about 40%.
3. Topdressing methods. The depth of topdressing is generally about 10 cm. Seedling-stage topdressing should be 10-12 cm away from the corn plants, and seed fertilizer and grain fertilizer should be 15-20 cm away from the plants. Only in this way can fertilizer efficiency be fully exerted and the fertilizer utilization rate be improved.