营养液是溶解的矿物盐的水基混合物，可将所有必需的植物养分直接输送到水培系统中的根部。它取代了土壤的矿物质供应作用。完整的营养液包含所有六种常量营养素（N、P、K、Ca、Mg、S）和植物可利用的离子形式的所有必需微量营养素，并调整到正确的pH范围，以使每种元素保持可溶和可吸收。
关键事实
- Must contain all 17 essential plant nutrients in bioavailable ionic form
- Target EC range varies by crop and growth stage: 0.8–3.5 mS/cm for most crops
- Optimal pH for most hydroponic crops: 5.5–6.5 (different elements absorb best at different sub-ranges)
- Temperature affects dissolved oxygen and nutrient uptake — keep at 18–22°C (65–72°F)
- Must be replaced or topped up regularly as plants absorb nutrients and water at different rates
- Recirculating systems require weekly EC and pH monitoring; top off with plain water not full solution