The key to selecting fertilizer lies in matching the crop's nutritional requirements and growth stage, while also considering soil conditions to avoid potential issues. Different types of crops have distinct nutritional needs; you can refer to the following guidelines:
Selecting Fertilizer Based on Crop Type
Grain Crops: For rice, use a formula with an N-P-K ratio of 1:0.3:0.8 (e.g., 24-7-19). For corn, apply a balanced compound fertilizer as a base dressing, followed by a high-nitrogen fertilizer during the "large bell" (rapid vegetative growth) stage; since corn is tolerant to chlorine, chlorine-based compound fertilizers can be used.
Leafy Vegetables: Prioritize nitrogen, with an N-P-K ratio of 1:0.2:0.5. For fast-growing leafy greens, follow the principle of "frequent, light applications"-apply quick-acting nitrogen fertilizer once when the plant has 2–3 true leaves and again during the period of vigorous growth.
Fruiting Vegetables: Use an N-P-K ratio of 1:0.4:0.8. Increase phosphorus and potassium before flowering, and focus on potassium supplementation after fruit set and during the fruit-enlargement stage. Also, include secondary and micronutrients like calcium and boron to prevent fruit cracking.
Root and Tuber Crops: Use an N-P-K ratio of 1:0.3:1.5. During the enlargement phase, significantly reduce nitrogen and focus on potassium. For chlorine-sensitive crops (such as potatoes and sweet potatoes), use sulfur-based compound fertilizers to avoid interfering with starch accumulation.
Fruit Trees: For citrus and pomelo, use formulas such as 15-6-12 or 20-7-22, applied in three stages: post-harvest, pre-flowering, and post-blossom. Bananas require high levels of potassium; a specialized 15-6-23 formula is recommended.
Leguminous Crops: Emphasize phosphorus and potassium while limiting nitrogen. Supplement with molybdenum to enhance the nitrogen-fixing activity of root nodules, and avoid excessive nitrogen, which can lead to over-vegetative growth (excessive foliage at the expense of yield).
