Application Techniques For Water-Soluble Fertilizers
Water-soluble fertilizers offer significant advantages in terms of improving fertilizer utilization efficiency, conserving agricultural water, reducing environmental pollution, enhancing crop quality, and saving labor. However, when applying them, one should master the following techniques based on their specific characteristics:
Avoid direct application; use a two-step dilution method
Water-soluble fertilizers have higher nutrient concentrations than standard compound fertilizers, meaning lower application rates are required. Direct application can easily cause root damage or "fertilizer burn," leading to stunted or weak seedlings. A two-step dilution process not only ensures uniform application but also improves nutrient utilization efficiency.
Apply small amounts frequently
Because water-soluble fertilizers act quickly and do not persist long in the soil, the principle of "little and often" is crucial. This aligns with the plant root system's need for continuous nutrient uptake and minimizes leaching losses associated with heavy, one-time applications. Generally, the application rate is 3–6 kg per mu (approx. 0.2–0.4 kg per 100 m²) per application.
Ensure nutrient balance
Water-soluble fertilizers are typically applied via soil drenching, foliar spraying, or injection into irrigation systems (such as drip or sprinkler irrigation). It is important to note that with drip irrigation, dense root growth reduces reliance on soil-based nutrients, making the crop more dependent on nutrients supplied through the irrigation system itself. An unbalanced fertilizer formula can hinder crop growth. Furthermore, water-soluble fertilizers should never be applied using traditional flood irrigation or free-flowing water methods, as this leads to waste and uneven distribution.
Use in combination with other fertilizers
Water-soluble fertilizers are fast-acting and generally serve only as top-dressing; they cannot replace conventional fertilizers in standard agricultural production. A balanced approach-combining base fertilizers with top-dressing, organic with inorganic fertilizers, and water-soluble with conventional fertilizers-helps reduce costs and maximizes the specific benefits of each fertilizer type.
Apply alone or mix only with non-alkaline pesticides
Farmers often use foliar sprays of water-soluble fertilizer to alleviate nutrient deficiencies or poor root growth in vegetables. However, it is advisable to apply these fertilizers alone or mix them only with non-alkaline pesticides. Mixing with alkaline substances can cause metal ions to react and precipitate, potentially leading to leaf damage from the fertilizer or pesticide.
Avoid Excessive Irrigation
When irrigating primarily for fertilization, apply only enough water to moisten the root zone. Root zone depths vary significantly among crops; you can determine the specific depth by digging into the soil with a spade. Excessive irrigation not only wastes water but also causes nutrients to leach below the root zone-rendering them inaccessible to the crop and wasting fertilizer. This is particularly true for urea and nitrate-based nitrogen fertilizers (such as potassium nitrate, calcium ammonium nitrate, nitro-phosphate fertilizers, and water-soluble fertilizers containing nitrate nitrogen), which are highly susceptible to loss via water runoff or leaching.
Prevent Surface Salt Accumulation
Long-term use of drip fertigation in greenhouses or polytunnels can lead to salt accumulation on the soil surface, which hinders root growth. Drip irrigation beneath plastic mulch can be employed to inhibit the migration of salts to the soil surface.
