Fertilizer Requirements and Key Fertilization Techniques for Rice at Different Growth Stages
I. Fertilizer Requirements of Rice. Nitrogen, phosphorus, and potassium are the nutrient elements that rice requires in relatively large amounts while soils are relatively deficient in them. Generally, for every 100 kg of rice grain produced, about 1.6-1.9 kg of nitrogen, 0.8-1.3 kg of phosphorus, and 1.8-3.8 kg of potassium are absorbed, with a ratio of approximately 1:0.5:1.3. Nitrogen uptake is highest from the greening stage to the tillering stage...
I. Fertilizer Requirements of Rice
Nitrogen, phosphorus, and potassium are the nutrient elements that rice requires in relatively large amounts while soils are relatively deficient in them. Generally, for every 100 kg of rice grain produced, about 1.6-1.9 kg of nitrogen, 0.8-1.3 kg of phosphorus, and 1.8-3.8 kg of potassium are absorbed, with a ratio of approximately 1:0.5:1.3. Nitrogen uptake is highest from the greening stage to the tillering stage, while phosphorus and potassium uptake is highest at the jointing stage. Rice forms two peak nutrient uptake periods for these three elements, respectively at the full tillering stage and the late young panicle differentiation stage. Therefore, rice fertilization must fully meet the rice plant's needs for various nutrient elements during these peak uptake periods, based on these nutritional patterns and nutrient uptake characteristics.
II. Rice Fertilization Techniques
1. Seedbed Fertilization Techniques. First, prepare nutrient soil: mix fertile upland soil and decomposed pig manure at a 7:3 ratio and compost; second, topdressing of seedlings: after the 3-leaf stage, if leaves generally turn green-fading and yellow due to nutrient deficiency, apply 16-20 kg of monopotassium phosphate or ammonium sulfate per mu of seedbed, diluted in 1200-1500 kg of water for foliar spraying; after spraying, rinse with clean water to prevent seedling burn; third, marriage fertilizer: preferably apply a marriage fertilizer once two days before transplanting to ensure rapid greening after transplanting, generally at 10 kg of ammonium sulfate or 5 kg of urea per mu.
2. Main Field Fertilization Techniques. Main field fertilization should combine organic fertilizer with chemical fertilizer, and topdressing with foliar spraying. The fertilization principle is to reduce nitrogen and increase phosphorus and potassium. In conjunction with autumn or spring land preparation, fully decomposed farmyard manure can be applied every other year at 2-3 t per mu; then, in conjunction with harrowing, apply high-quality rice formula fertilizer at 15-25 kg per hectare; tillering fertilizer: apply in two applications. The first tillering fertilizer is applied immediately after greening at 50% of the total amount, no later than the 6-leaf stage, to promote early and rapid tillering and low-position tillers; when rice reaches the end of the 7th leaf to the emergence of the 8th leaf tip, apply the second tillering fertilizer; panicle fertilizer: apply in two applications. The first application is when the 3rd leaf from the top just emerges, applying 60% of the total panicle fertilizer to promote differentiation of the panicle, branches, and spikelets and strive for large panicles; the second application is when the flag leaf (1st leaf from the top) emerges. Panicle fertilizer is mainly nitrogen fertilizer with an appropriate amount of potassium fertilizer added.