1. What nutrients are essential for rice throughout its growth cycle?
Rice plants rely on their leaves, sheaths, and stems to absorb light, heat, and carbon dioxide, while their roots take up water and various nutrients to produce organic matter. These nutrients include a wide range of elements, from macronutrients to micronutrients and special elements. Major nutrients include carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Micronutrients such as iron, manganese, and molybdenum also play crucial roles, while silicon is considered a special element. In total, rice requires 16 essential nutrients for healthy growth.2. What are the fundamental principles governing nutrient uptake in rice?
The absorption of nutrients by rice follows two key laws: the law of diminishing returns and the non-replaceable principle. The law of diminishing returns states that after a certain point, applying more nutrients does not lead to increased yield, and in some cases, it can even reduce production. This is especially noticeable with nitrogen, followed by phosphate. The non-replaceable principle emphasizes that each nutrient has a unique role and cannot be substituted. If one nutrient is lacking, it becomes a limiting factor for growth and productivity.3. Why is organic fertilizer emphasized in rice cultivation?
Organic fertilizers are rich in organic matter and humus, which improve soil structure and provide a slow-release source of nutrients. They enhance soil's ability to retain water and nutrients, promote better root development, and improve overall soil health. However, in many northern rice areas, the use of organic fertilizer is limited, leading to poor soil quality, reduced water retention, and weaker plant growth. This often results in lower yields, making the addition of organic fertilizer essential for sustainable rice farming.4. What are the physiological effects of nitrogen, phosphorus, and potassium on rice? What are the symptoms of deficiency and excess?
Nitrogen is vital for chlorophyll production and protein synthesis, promoting leaf and root development. A deficiency leads to yellowing, narrow leaves, and stunted growth, while excess nitrogen causes excessive tillering and weak stems. Phosphorus supports root development, grain formation, and starch synthesis. Deficiency results in dark green leaves, poor tillering, and delayed maturity, while excess phosphorus may cause zinc deficiency. Potassium enhances root vitality, delays leaf aging, and improves disease resistance. A lack of potassium causes leaf burn, weak stalks, and poor grain filling, while overuse typically has no significant effect on yield.5. What are the recommended amounts of N, P, and K for producing 500 kg of rice?
For hybrid rice, the requirement is approximately 13 kg of nitrogen, 7.5 kg of phosphate, and 21 kg of potash. For conventional rice, it’s about 15 kg of nitrogen, 8.5 kg of phosphate, and 22 kg of potash. The ideal ratio of N:P:K is 2:1:3.6. How can we improve the efficiency of nitrogen and phosphate fertilizers in paddy fields?
To increase nitrogen utilization, apply it deeply as base fertilizer, which can boost efficiency by 10-15%. For phosphate, concentrated application methods such as soaking seedlings’ roots, applying it 1-2 days before transplanting, mixing with green manure, or incorporating green manure into the field are more effective than spreading it evenly.7. Why should potash be used in rice cultivation? What types of potash are available?
Potash is essential because rice consumes large amounts of potassium, and potassium-deficient soils are becoming more common. Applying potash significantly increases yield. Common types include potassium chloride (KCl), potassium sulfate (Kâ‚‚SOâ‚„), and wood ash.8. What are the typical fertilization methods used in rice areas today?
Rice fertilization generally includes base fertilizer and top dressing. Base fertilizer is applied before transplanting, often combined with organic and chemical fertilizers. Top dressing occurs after transplanting and includes green manure, tiller fertilizer, panicle fertilizer, and grain fertilizer.9. Why is layered fertilization important?
Deep application of chemical fertilizers improves nutrient stability and utilization. Studies show that deep application of ammonium bicarbonate increases yield by 13-19% compared to surface application. It reduces nitrogen loss, improves root absorption, and ensures a steady supply of nutrients over 40-50 days, enhancing grain quality and yield.10. How should base fertilizer and tiller fertilizer be applied?
Apply base fertilizer in three stages based on the plant's needs. First, 5–7 days after transplanting, use 5.5 kg of ammonium sulfate along with some superphosphate and zinc sulfate. Reapply every 10–20 days, and ensure a final application 5–10 days before the end of the tillering phase to maintain balance and promote healthy growth.Articulated Bolt, also known as fisheye bolt abroad, follows DIN444 standard. Refined eyelet bolt, with smooth spherical surface, high thread accuracy, and thread specification of M6 to M64.
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