Fertigation in Agriculture

Fertigation combines both fertilization and irrigation. Many plants need supplemental nutrients that are not found in the soil. So, fertilizers are added into an irrigation system. These fertilizers are dissolved completely in irrigation water in advance, kept in stock tanks, and then delivered to soil.

Fertigation is a combination of any of the following: ammonium nitrate, urea, ammonia monoammonium, phosphate, diammonium phosphate, or potassium chloride.

Advantages of Fertigation

• Fertilizer application is more accurate and uniform.
• Fertilizers are applied to specific areas, where they are needed.
• Nutrients are immediately available to plants and uptake of nutrients by roots is improved. (Nutrients and water are supplied near the active root zone through fertigation which results in greater absorption by the crops)
• It reduces the amount of fertilizer utilized and minimizes nutrient losses. Efficiency through fertigation ranges between 80-90 per cent, which helps to save a minimum of 25 percent of nutrients.
• It helps to save water, because plants develop a healthier root system.
• It saves time, labor and energy.
• It reduces soil erosion and water consumption.
• As water and fertilizer are supplied evenly to all the crops through fertigation there is possibility for getting 25-50 per cent higher yield.

Factors to consider for Fertigation

• Fertilizer compatibility with each other
• Fertilizer solubility in water or other media
• Types of fertilizers to be used whether dust, solid, or liquid
• Number of stock tanks
• Injection ratio or injection time
• The use of chelates
• Interaction of fertilizers with water (endothermic reactions, reactions with elements present in water)

Fertigation Methods

There are two fertigation approaches: The Quantitative Fertigation and the Proportional Fertigation. There is of course a simpler method by putting the fertilizer tank above ground and then fertigation takes place through drip lines with gravity. This is not considered here.

The quantitative approach is commonly used in open fields. The grower first decides how much fertilizer has to be applied per area (e.g. kg/ha, lbs/acre). This quantity of fertilizer is then delivered through the irrigation water. A bypass fertilizer tank is a simple method for fertigation in this method. Initially the concentration of nutrient is greater and decreases as water irrigation continues.

The proportional approach is the choice of most persons. Here, a defined quantity of fertilizer stock solution is injected into each unit of water flowing through the irrigation system (lbs/gal).