What are the technical essentials of fertilizing dryland crops?
Fertilizer needs to be applied in production, and the application methods differ between paddy fields and dryland, because the soil environments of paddy fields and dryland are different, and the soil properties are also different. In order to give full play to the fertilizer efficiency when applying fertilizer in dryland, the following technical essentials should be followed.
1. Deep application of nitrogen fertilizer. Deep application can reduce nutrient loss. On calcareous soil, nitrogen fertilizer is easily decomposed and volatilized, causing nitrogen loss. After deep application, the nutrients can be adsorbed by the soil, reducing nutrient volatilization and improving the nitrogen fertilizer use efficiency. Phosphorus moves very little in the soil, and deep application can increase the contact between fertilizer and crop roots.
Deep application of fertilizer is conducive to root development. Crop roots have the habit of growing toward the center of the earth and toward fertilizer. Deep application of fertilizer can promote roots to grow downward, enhance the roots' ability to absorb and utilize fertilizer, and also make full use of deep soil moisture, playing the role of promoting roots with fertilizer, drawing water with roots, and resisting drought with water.
Deep application of fertilizer is conducive to nutrient dissolution, transformation and crop absorption. The surface layer of dryland soil is mostly in a dry state in spring. If fertilizer is applied too shallowly, it will not play its due role in increasing yield. Especially for phosphate fertilizer, the farther it is from the roots, the worse the effect.
The suitable fertilization depth is 12-16 cm. For crops sown relatively shallowly, the fertilizer can be applied deeply before sowing and then sowing can be carried out. For particularly barren land, in addition to deep application as base fertilizer, attention should be paid to applying an appropriate amount of seed fertilizer, which is conducive to crop seedling development.
2. Autumn fertilization. Applying fertilizer into the soil in late autumn after the rainy season ends can promote early seedling emergence of spring-sown crops, with complete and strong seedlings, and play a role in drought resistance, freezing resistance and yield increase. Autumn fertilization must be deep, 12-16 cm is sufficient. The time is suitable in mid-to-late October. If the rainy season ends late, it can also be extended to early November. If it rains after fertilization, soil moisture and fertilizer should be preserved. Autumn fertilization is the same as spring application, with farmyard manure and chemical fertilizer applied together. Organic fertilizer has complete nutrients, and its fertilizer effect is slow but lasting. It cannot be replaced by chemical fertilizer in terms of building soil fertility and organic nutrients. Chemical fertilizer should be combined with nitrogen and phosphorus to avoid nutrient imbalance. Optimal fertilizer combinations can make the best use of advantages and avoid disadvantages, playing a better role.
3. Apply enough fertilizer at one time. Because precipitation periods and rainfall amounts vary greatly, it is difficult to topdress fertilizer when crops need it most. Topdressing after rain, topdressing before light rain, or topdressing too late all result in very low fertilizer use efficiency and yield increase effect. Sometimes topdressing in the early stage has no effect due to little rain, while in the later stage with more rain, it instead causes excessive vegetative growth and late maturity. Therefore, chemical fertilizer must be applied as base fertilizer at one time in sufficient amount, and generally no more topdressing is needed. In this way, crops can grow steadily, emerging early as small seedlings with drought and freezing resistance, and in the later stage they will not lack fertilizer and prematurely age, and can normally turn yellow and mature.
4. Economical and rational application of chemical fertilizer. Quantifying the amount of chemical fertilizer used is an important part of modern agricultural production. The reduction of per capita land and the improvement of living standards force increasing investment in land. The suitable application amount of chemical fertilizer on dryland varies greatly depending on land, climate and crop conditions. In particular, the precipitation during the crop growing season is the main condition determining fertilizer effect and application amount. If soil in the 0.2-2 m deep soil layer cannot be formed into a ball when gently pinched by hand, it indicates that the bottom soil moisture is very poor, so the fertilization amount for dry years should be adopted. If it can be formed into a ball when gently pinched and does not break when dropped on the ground, it indicates that the bottom soil moisture is relatively sufficient, so the fertilization amount for years with more rain can be adopted. For fertile land with more farmyard manure, the lower limit of fertilization can be adopted; otherwise, the upper limit of fertilization amount can be adopted. In dry years, the proportion of phosphate fertilizer can be appropriately increased, and on bean stubble land, the amount of nitrogen fertilizer can be slightly reduced. Attention should always be paid to input-output accounting to improve the economic benefits of chemical fertilizer.