In the cultivation of early rice, potassium-reducing phosphorus can be used as a phosphorus fertilizer, while late-season rice may require less or no additional phosphorus. When using compound fertilizers as top dressing, nitrogen and potassium-based compound fertilizers are recommended, which help keep fertilizer costs relatively low. For late rice, applying 25-30 kg of a 25% compound fertilizer per mu along with 5 kg of potassium chloride yields results comparable to 20-25 kg of a 45% compound fertilizer, but at a cost that is more than one-third lower. Alternatively, 30-35 kg of a 20% nitrogen-potassium compound fertilizer can be applied per mu. Urea (15-20 kg) and potassium chloride (10-15 kg) can also be used as top dressings. If ammonium bicarbonate or compound fertilizer was applied as base fertilizer, then for top dressing, urea should be applied at 10-15 kg per mu, and potash fertilizer at 5-15 kg.
For nitrogen management in late rice, an "early application" strategy is recommended. If the previous crop was corn or early rice, it's important to maintain proper nitrogen levels, applying 15-20 kg of urea per mu for top dressing without unnecessary reductions. If the previous crop was watermelon or peppers, about 7.5-10 kg of urea per mu is typically sufficient. For fields previously planted with legumes like soybeans or peanuts, less nitrogen is needed—around 5-7.5 kg of urea per mu. When returning straw to the field, it’s crucial to apply available nitrogen early to avoid nitrogen deficiency caused by microbial competition. Usually, top dressing with nitrogen is done about five days after the late rice has been cut, and it’s often combined with potassium fertilizer.
Middle-season spiker hybrid late rice varieties tend to produce large panicles, and their yield largely depends on these big spikes. Therefore, during the mid-stage of late rice growth, it's important to provide adequate nutrients. If leaves begin to yellow or if there's a noticeable lack of nutrients in the field, applying 2-3 kg of urea per mu after irrigation can help restore plant health. However, the dosage must be strictly controlled to avoid excessive growth.
During the heading stage of late rice, applying grain fertilizer is essential. For each mu, 50 grams of full-grain fertilizer combined with 250 grams of urea can be mixed with 50 kg of water and sprayed onto the foliage. Alternatively, 300 grams of potassium dihydrogen phosphate plus 250 grams of urea in 50 kg of water can also be used for foliar application.
Author: Long Vanves
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