[Runzi Agricultural Technology] Are the effects of spraying foliar fertilizers on crops better than those of conventional fertilizers?

Why apply foliar fertilizer? How to improve its effectiveness? Let’s find out together!

I. What is Foliar Fertilizer?

Foliar fertilization is the practice of spraying fertilizer solutions to allow plants to absorb nutrients through their leaves. Fertilizers designed to be applied directly to crop foliage for foliar absorption are called foliar fertilizers.Nutrients enter the plant directly through the leaves, participating in metabolism and organic synthesis, making foliar fertilization faster and more effective than soil fertilization. It is often used to promptly correct nutrient deficiencies in crops. Split applications can be made according to growth stages, seedling conditions, and soil nutrient supply, ensuring normal growth, high yield, and good quality.

II. Why Apply Foliar Fertilizer?

1. Compensate for insufficient root fertilizationWhen root fertilization is inconvenient — such as in late growth stages with declining root activity and nutrient uptake, or under unfavorable soil conditions (excess water, drought, extreme acidity or alkalinity) — foliar application quickly replenishes nutrients to restore growth.

2. Rapid nutrient supplementationWhen crops show nutrient deficiency symptoms, soil fertilization takes time to take effect. Foliar fertilization delivers nutrients directly through leaves to resolve deficiencies immediately.

3. Maximize fertilizer efficiencyFertilizers such as phosphorus, iron, manganese, copper, and zinc are easily fixed in soil when applied to roots, reducing effectiveness. Foliar spraying avoids soil constraints. For deep-rooted fruit trees and crops, foliar application achieves better results than traditional soil fertilization.

4. Cost-effectiveTrace elements are essential but required in very small amounts. For instance, molybdenum fertilizer needs only dozens of grams per mu, making uniform soil application difficult. Studies show boron utilization from foliar spraying is 8.18 times higher than basal soil application, making it far more economical.

5. Reduce soil pollutionHeavy nitrogen application leads to nitrate accumulation in groundwater and vegetables, threatening human health (about 75% of human nitrate intake comes from vegetables). Foliar application reduces soil fertilizer rates, lowering nitrate levels in plants and residual mineral nitrogen in soil. It also avoids increasing soil solution concentration and worsening salinization, protecting both soil and water sources.

III. Advantages of Foliar Application

1. Low dosage, economicalSoil application of micronutrients as base fertilizer requires 0.5–2.0 kg per mu with poor results. Foliar spraying uses only one-fifth the rate, with dilute concentrations, and is easily absorbed by crops.

2. High fertilizer efficiencyNutrients enter through leaf cuticles and stomata without direct soil contact, avoiding fixation and loss of effectiveness.

3. Fast absorption and high efficiencyDirect contact with stems and leaves enables rapid uptake and transport.

4. Easy concentration controlAdjustable application concentrations prevent toxicity and ensure safety.

5. Environmentally friendlyLow application concentrations (usually diluted to 0.1%–0.3%) and small dosages minimize environmental pollution.

IV. How to Improve Foliar Fertilizer Effectiveness

Many farmers believe more fertilizer means better results, even mixing multiple fertilizers for enhanced effects. This is incorrect; proper methods alone can meet crop growth needs.

Highly volatile fertilizers such as ammonia water and ammonium bicarbonate must not be used as foliar fertilizers, as high temperatures can burn leaves. Most micronutrients should not be mixed with pesticides arbitrarily, nor should acidic and alkaline fertilizers be combined blindly. Targeted mixing of fertilizers and pesticides can achieve “one application, multiple benefits”; improper mixing will be counterproductive.