According to studies, foliar fertilization—also known as spray fertilization—supplies the plant with both major and minor nutritional needs through the shoots instead of via the roots.
Tests have revealed that the leaves can absorb all the nutrients the stems and roots do. Furthermore, it is discovered that, generally speaking, nutrient absorption via the leaves is faster and more effective than that via the roots.
When ought one to apply foliar fertilization?
Since plant food is typically taken through the roots, it is observed that foliar fertilizers cannot be totally replaced with ground fertilizers since they are essential for plant growth. With ground fertilizers in some of the following situations, however, foliar fertilization is beneficial and required:
1. It requires effort to get the fertilizer elements required for development even if these elements are readily available in the soil when plants are subjected to critical periods of stress during their development. Furthermore, affecting the quantity and quality of the crop are some elements that might limit the degree to which the plant gains from the nutrients available to it and its incapacity to absorb, assimilate, and move them to various storage locations such as fruits, tubers, roots, branches, and new development. shelf life and marketing. For instance, the quality and type of the soil plants grow in determines most of the factors.
The elements present in sandy and limestone soils are compounds that are difficult to absorb through the roots; hence, tons of fertilizer must be added to these areas to satisfy the demands of the plants under ground fertilizing. Added to alkaline soil with a high calcium carbonate concentration, iron, zinc, and manganese also prove challenging. Variations in environmental and climatic factors.
2. in a way that cannot be absorbed due to the influence of some factors, in particular soil pH, a high degree of which leads to the deposition of elements in the soil, especially phosphorous and trace elements.
3. During vital phases of growth for plants. The plant's demand for potassium rises during the fruiting stage, which runs counter to magnesium given its demand; hence, magnesium has to be sprayed on foliage.
4. When the plant's root activity grounds parts to the pneumatic components. High groundwater levels cause poor soil ventilation, which simplifies irrigation and fertilization with irrigation water.
Root absorption efficiency in the soil is influenced by its high salt concentration. Root infection with soil diseases, particularly nematodes, reduces their absorption of nutrients' efficiency.
The smallness of the plant's root system means that the roots in the seedling must be enlarged to meet the plant's nutritional demands during the first stage of growth, that of seedlings. It does not take up elements from the ground and water. Extreme thirst can lead to root damage, particularly when insects or agricultural equipment cut the roots.
5. Early treatment is needed if symptoms of a deficiency of one or more elements show up in one of the phases of development. 6. Should weeds lower the land's nutrient efficiency, this will affect it overall.
Benefits of foliar fertilizer application
Studies have shown that some crops can obtain about 80% of their element needs through the leaves and stems, and the rest is obtained through the roots.
Most horticultural crops respond better to spray fertilization than ground fertilization. This may be because most lands tend to be alkaline, which reduces the sensitivity of many added elements, such as microelements and phosphorus, to root absorption.
The most essential advantages of foliar fertilization are the following:
1. The percentage of benefit from the nutrients added by spraying on the leaves is higher than by ground application. For example, the percentage of nitrogen added to the ground barely represents 60%, and in the case of phosphorus, it reaches 10-15%.
2. Providing added fertilizers, as small amounts of fertilizer are used compared to ground fertilization. For example, adding iron sulfate at a concentration of 4% at a rate of 120 liters per acre (an acre is 4,200 square meters) led to a significant increase in yield compared to adding about 200 kg of ferrous sulfate per acre on the ground, where the element is fixed in the soil.
3. Overcoming the problems of fertilizing lands that lead to a decrease in the efficiency of fertilizers, whether this is the result of factors that lead to the loss of fertilizer in the form of gas or loss by washing with irrigation water.
Such as nitrogen. Alternatively, determine their movement by stabilizing or precipitating them, such as phosphorus and trace elements. Since the pH of the soil has an apparent effect on the availability of nutrients, as the pH increases, the concentration of most trace elements and phosphorus in the soil solution becomes very low.
4. The speed of supplying the plant with its needs for elements during certain growth stages, such as flowering and fruiting.
The following must be taken into account when spraying:
2. The appropriate growth stage must be chosen for spraying. Spraying should begin once the leaves have matured and can absorb the nutrient solution because the spraying efficiency increases with the total percentage of mature vegetative leaves, especially young ones.
3. Spraying plants when thirsty or under harsh water conditions is not permissible. Therefore, it is not preferable to spray after irrigation.
4. A dispersing material must be added to the spray solution to increase the contact surface between the solution and the surface leaves, which increases the chance of absorbing nutrients through stomata, especially in the leaves, which contain a waxy substance such as garlic, onions, and cabbage.
5. Wash all leaves, including the bottom surfaces of the leaves.
6. When mixed with pesticides, this should not affect the efficiency of food compounds or pesticides.
7. Spraying should not be done when there is wind, rain, or a high temperature to prevent plant harm.
8- One must be careful not to increase concentrations, especially when fertilizing with significant elements, so leaf burning does not occur.
9. Using a non-ionic substance that helps absorb through the plant's stomata is preferable, especially when using chelated fertilizers. One of the cheapest materials is urea fertilizer (46%), used at a concentration of 0.5 per thousand (50 grams per 100 liters of spray solution), which may increase to 2 grams per liter. When combined with the ammonium ion, urea helps with the rapid absorption of phosphorus.
10. The absorption of elements is affected by the pH of the spray solution. The lower the spray solution pH 7, the more it increases the absorption rate of elements, whether in new or immature leaves.
11. Be careful not to use spray water whose salinity exceeds 500 parts per million.
12. One must be careful not to fertilize by spraying before three days have passed since the last pesticide treatment, whether they were added to pesticides in the soil or sprayed on plants.
13. The spraying process must be repeated according to the plant's needs and the appearance of element deficiency symptoms. The plant.
14. Adherence to the concentrations specified on the foliar fertilizer packages is considered.