How to apply the three fertilizers well for rice? Detailed explanation of the key points of fertilization methods

Excessive vegetative growth of seedlings causes ineffective tillers to proliferate rapidly, leading to delayed maturity with excessive greenness; some seedlings grow so densely shaded that they trigger diseases such as sheath blight or rice blast. In paddy fields where fertilizer damage occurs, it causes yield reduction in mild cases and forces the seedlings to be plowed up and replanted in severe cases.

To give full play to the fertilization effect on rice, in addition to applying sufficient base fertilizer, the "three fertilizers" must be applied well as topdressing, namely tillering fertilizer, panicle fertilizer and grain fertilizer. Rice fertilization should be considered comprehensively and applied flexibly according to variety characteristics, soil fertility, climate factors and cultivation conditions. The fertilizer demand of rice is expressed in the nutritional stage, the critical nutritional period and the period of maximum nutritional efficiency. For example, early rice has a short growth period and relatively low fertilizer demand, so fertilization should be early and concentrated. Middle rice and late rice have longer growth periods, larger fertilizer demand and higher intensity, so the number of topdressings should be increased and the proportion of topdressing raised. The critical nutritional period for nitrogen and phosphorus in rice generally appears at the three-leaf stage, and sometimes the critical nutritional period for nitrogen and potassium also appears at the young panicle differentiation and young panicle formation stages. The period of maximum nutritional efficiency in rice appears at the long panicle stage, which is the most vigorous stage of vegetative growth and reproductive growth, and also the key period of fertilizer demand.

According to research, for every 100 kg of rice grain produced, about 1.6-2.5 kg of nitrogen, 0.8-1.2 kg of phosphorus and 2.1-3.0 kg of potassium need to be absorbed from the soil. The ratio of the three elements is 2:1:3.

After understanding the fertilizer requirement patterns and characteristics of rice, reasonable topdressing should be carried out in stages.

1. Apply tillering fertilizer early. Topdressing from transplanting to the beginning of young panicle differentiation is called tillering fertilizer. Tillering fertilizer should be applied early and in sufficient quantity; generally, the amount of tillering fertilizer accounts for 50%-60% of the total topdressing. This is because the tillering stage is the first peak period of nitrogen nutrition absorption in the life of rice, and because air temperature, water temperature and soil temperature are all relatively low in the early growth stage of rice, nutrient release is slow, and too little topdressing cannot meet the rice's nutrient needs. Only early application can help rice tiller early and tiller more, and lower the tillering node position. Tillering fertilizer is applied 7-10 days after rice transplanting, with 5-7 kg of urea per mu. If the base fertilizer is insufficient, it can be appropriately increased, but excessive topdressing must not be applied blindly to prevent excessive growth.

2. Apply panicle fertilizer skillfully. Topdressing from the beginning of young panicle differentiation to before heading is called panicle fertilizer. It is also the second peak period of nitrogen absorption. Applying panicle fertilizer well can preserve flowers and increase grains, promote large panicles and more grains, and prevent excessive greenness and lodging. Technically, several points should be achieved: first, do not apply it to fields with good soil fertility, sufficient base fertilizer and many tillers; second, apply it where leaves do not carry dew in the morning, blades are upright at noon, and leaf color is light yellow; third, do not apply it on rainy days, and apply it promptly on sunny days. The application time is the rice stem elongation stage. Apply 3-4 kg of urea per mu, together with a small amount of phosphorus and potassium fertilizer, and spray 50 kg per mu of 0.2%-0.3% potassium dihydrogen phosphate solution on the leaves.

3. Apply grain fertilizer as appropriate. Topdressing after heading is called grain fertilizer or seed-strengthening fertilizer. Grain fertilizer can extend the functional period of leaves, prevent premature senescence and increase grain weight. But note that it should not be applied where seedlings are not yellow, not applied on rainy days, and not applied in fields with disease. Choose a sunny afternoon to spray 1% urea solution, or 1:500 Huimanfeng active liquid fertilizer, 50 kg per mu. For paddy fields that have already developed sheath blight or rice blast, pesticides such as dimethachlon, iprobenfos, Jinggangmycin, Nongkang 120 and Xiaojunling should be selected for control.