Potassium-reducing phosphorus can be applied as a phosphorus fertilizer during the early rice growth stage, while late-season rice may require less or even no additional phosphorus. When using compound fertilizers as top dressing, nitrogen and potassium-based compound fertilizers are recommended, which helps keep overall fertilizer costs low. For late rice, applying 25-30 kg of a 25% compound fertilizer per mu along with 5 kg of potassium chloride is effective. This combination achieves results comparable to using 20-25 kg of a 45% compound fertilizer, but at a cost that is more than one-third lower. Alternatively, a 20% nitrogen-potassium compound fertilizer can be applied at 30-35 kg per mu. Urea (15-20 kg) combined with potassium chloride (10-15 kg) can also serve as an effective top dressing. If ammonium bicarbonate or compound fertilizer was used as base fertilizer, then for top dressing, 10-15 kg of urea and 5-15 kg of potash fertilizer per mu are typically sufficient.
In late rice cultivation, it's important to manage nitrogen carefully and apply it early. A "control" strategy should be adopted. If the previous crop was corn or early rice—both heavy nutrient consumers—then applying 15-20 kg of urea per mu as top dressing ensures adequate nitrogen levels without unnecessary reduction. However, if the preceding crop was watermelon or peppers, only about 7.5-10 kg of urea per mu is needed. When the previous crop was legumes like soybeans or peanuts, the need for nitrogen fertilizer is reduced, so applying 5-7.5 kg of urea per mu is usually sufficient. When returning straw to the field, special attention should be given to the early application of available nitrogen to prevent nitrogen deficiency caused by microbial competition. Normally, top dressing with nitrogen fertilizer is done about five days after cutting the rice, and it is often applied together with potash fertilizer.
For mid-season spiker hybrid late rice, the advantage lies in the large panicles, and yield largely depends on these big spikes. Therefore, during the middle of the late rice growth period, it’s important to ensure proper nutrition. If the leaves start to yellow or the field shows signs of nutrient deficiency, applying 2-3 kg of urea per mu after irrigation can help restore plant health. However, this must be done carefully to avoid over-application, which could lead to delayed maturity.
During the heading stage, applying grain fertilizer is crucial. For each mu, 50 grams of full-grain fertilizer combined with 250 grams of urea can be used, or alternatively, 300 grams of potassium dihydrogen phosphate mixed with 250 grams of urea dissolved in 50 kg of water and sprayed onto the foliage. This helps enhance grain development and improve overall yield.
Author: Long Vanves
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