Foliar Fertilizer and its Applications

While growing healthy plants, application of plant nutrients in form of fertilizer is a common practice adopted by farmers and growers. And when we say fertilization, it refers to application of plant food in the growing medium (or soil).

The objective is to make the nutrients available to the roots, so that they absorb and transfer them to the remaining plant parts. A concept different to this is providing foliar fertilizer, which promises to give better results than the soil based fertilizers.

In botanical terms, the terms leaves and foliage are used colloquially. They are the main organs responsible for production of food by plants by means of photosynthesis. Thus, a plant nutrient created for leaf feeding is referred to as a foliar fertilizer. As you have seen, soil applied fertilizer is sold in solid granules, or powders in some cases.

In fact, a major concern of using solid fertilizers is their absorption by plant. It is observed that minimal amount of the applied plant food reaches the plants, and the remaining is wasted in the soil. Over time, the unused chemicals are washed down to nearby water bodies and ground water. Thus, these agriculture related wastes lead to pollution of water.

So, when to use foliar fertilizer? If soil pH, waterlogged soil and alike factors are limiting nutrient uptake by the roots, foliar fertilization is the ultimate plant care step. It is best done, when the roots are not able to absorb soil nutrients.

However, it is to be borne in mind that not all nutrients can penetrate the leaf, fruits and upper plant parts. Thus, correct identification and purchasing of plant food should be considered while feeding plants through leaves. Refer to the following information for better understanding about foliar fertilization.

In preparation of liquid fertilizers, specific amounts of the major plant nutrients (nitrogen, phosphorous and potassium, or simply NPK) are combined to get the desired fertilizer type.

Say for example, in production of liquid potash fertilizer, the quantity of potassium is more than nitrogen and phosphorous. Also, there are liquid fertilizers developed for reducing deficiency of calcium, zinc and other trace minerals.

As aforementioned, a foliar fertilizer is created for applying in the foliage. It is sprayed early in the morning or late at night, so that the nutrients are absorbed via the leaf stomata. It can also be added in irrigation system and hydroponic gardening.

Since essential plant nutrients are present in dissolved form, they are available to the plant parts immediately after application. The worrying issue with foliar sprays is increased risk for toxicity, even in slight increase of the recommended dose.

Comparative studies have been done to compare the effectiveness of foliar fertilizer and soil applied fertilizer type in improving plant health.

The results reveal that the former nutrient form is about eight times more effective than solid fertilizer, in terms of dose applied and speed of assimilation. After foliar feeding the plants, a significant increase in respiration, water absorption and cellular activity is observed.

The major advantage with foliar fertilizers is their efficiency, even in low dosage. Since the essential plant nutrients are available shortly after application, these liquid nutrients are beneficial to solve temporary nutrient stress.

In case of solid fertilizers, there are certain factors that affect the availability of nutrients to the root system. For instance, regular watering is necessary after fertilizer application to ensure dissolution of the dry nutrients.

As you now have a brief idea about 'what is foliar feeding', you can use foliar sprays correctly. Based on your gardening project, you can select organic foliar fertilizer (for vegetables and food crops) or chemical based liquid fertilizer for use in ornamental plants.

Remember that the nutrient concentration is usually higher than that of ground applied fertilizers. Thus, check the dose and refer to the manufacturer guidelines before foliar feeding plants.