By: Lior Doron – Crop Management Technology Director
Fertilization is in widespread use by farmers, in order to provide crops the nutrients essential for their growth – both in quality and quantity. Chicken manure and compost are commonly used as fertilizers, as well as readymade products.
The amount of fertilizer that the crop gets determines the quality and quantity of the crop produced. The following figure demonstrates the relationship between the amount of fertilizer to the plant growth and yield. Too little fertilizer under-nourishes the crops, whereas too much wastes expensive fertilizer, pollutes the environment, and in some cases, even poisons the crop. There is a very small area of optimal fertilization.
Traditionally, fertilizer is applied by scattering it over the entire area where the crop grows. But while the purpose of fertilization is to enhance the quality of crops and accelerate their growth, traditional methods often yield negative effects and challenges:
- Wasteful – Scattering fertilizer on the ground, instead of only to the roots, is extremely inefficient and wasteful. Furthermore, with rainwater or flood/furrow irrigation, the fertilizer goes down below the root zone, even before it has a chance to benefit the crop. With fertilizer being extremely expensive, this means unnecessary money down the drain for the farmer.
- Environmentally unfriendly – With rainwater or flood/furrow irrigation, the scattered fertilizer may find its way to the groundwater, severely polluting the underground water resources.
- Detrimental to crops – Scattering fertilizer can result in too little fertilizer reaching the crop, producing deficient and low yield crops (the Visible Deficiency Symptoms area in the above figure). It can also result in excessive fertilization, which can poison the crop (the Visible Toxicity Symptoms area in the above figure). This of course defeats the whole purpose of applying fertilizer.
- Inefficient –There is quite a large area, where adding more fertilizer does not damage the crop, but also does not benefit it (the Luxury area in the above figure). Applying more fertilizer without any improvement in crop yield or quality wastes very expensive fertilizer and pollutes the environment without any purpose at all.
In this article, I will discuss how the combination of drip irrigation and Crop Management Technology (CMT) systems can provide a solution to the challenges mentioned above, enabling the use of fertilizers in an optimized and accurate manner for each specific crop.
CMT Systems with Fertigation Provide Solutions for Traditional Fertilization Challenges
Applying fertilizers with irrigation water (fertigation) enables increased absorption of the nutrients by the plant’s roots. Typically, only part of the fertilizers, which are scattered on the ground, actually reach the roots. Of course, as fertilizers are generally much more expensive than water, using drip irrigation as the means to deliver fertilizers directly to the plants’ roots is of upmost importance. Yet, due to the sensitivity of the crops to the amount of fertilizers that are applied, the delivery of the fertilizers must be controlled and accurate.
Netafim developed a variety of user-friendly crop management technology systems to control the amount of fertilizer administered to crops through fertigation. Using this technology, fertilizer is administered to the crop through the drip irrigation system, and is monitored and controlled by a CMT dosing system. The CMT dosing system directs the grower to work in the Target area (see figure above) and apply the optimal amount of fertilizer, without needlessly wasting money or polluting the environment.
As mentioned in my previous post, Netafim not only provides the systems; it also adds agronomic knowledge based on best practices for each crop and land/climate characteristic. Netafim’s agronomists predefine into the CMT system, the amount of fertilizer required for each type of crop.
As part of the process, the grower pours the exact amount of each type of fertilizer into the system. Depending on the model used, up to eight fertilizers can be applied at once, each in a separate dosing channel. After the system checks that the correct amounts of fertilizers were poured into the machine, the fertigation system injects precise doses of each fertilizer into the irrigation water.
The various fertilizers are thoroughly mixed with the water through a dosing machine in a Mixing Chamber (registered patent of Netafim). This ensures that the concentration of fertilizer in the water is uniform, so that all crops get the same amount of fertilizer.
In open fields, precise fertigation is spread over the entire duration of the irrigation. The controller knows the duration of irrigation, as well as the amount of water and fertilizer required, and can spread the doses of fertilizer throughout the irrigation. The controller also knows the amount of time it takes the water to travel from the fertigation system to the drippers (this depends on the size of the field and the distance from the irrigation room to the field), and takes this into consideration by stopping the fertilization before irrigation ends. This method, called Proportional Fertilization, is very important in order for the fertilizer to be distributed equally to all the crops. The exception is the case of an open field where the quantity per irrigation is around 150-200 mm. In this case, a special short “technical fertigation program” is applied, in order to avoid leaching.
The system monitors and regulates tens of variables, such as amounts of water used, mix of fertilizers and micronutrients, and fertigation parameters.
In greenhouses, it is customary to also take into account the EC (level of electric conductivity) and pH (level of acidity) of the irrigation water, in order to create the best possible nutrient conditions for the crop. The EC level resulting from the fertilizer together with the EC of the water source must not exceed a certain level (different for each crop and type of substrate). Otherwise, the crop will not be able to absorb the water and fertilizer. The controller, together with the fertigation system, knows to keep correct EC and pH levels, while administering the required amounts of fertilizers.
In some cases, field-based sensors provide an extensive outlook of the field, providing information for a wide array of factors, from climate information to soil humidity, plant sensors, and system performance.
Fertigation with a CMT system provides the following solutions for fertilization challenges:
- Economical – Fertilizer is injected directly to the root zone of the plant, where it is needed, instead of being scattered all over the field.
- Efficient – CMT systems know how to direct growers to put exactly the right amount of fertilizer required by the crop to achieve the best possible results. Mixed with water using a dosing machine it results in a stable, homogeneous application and a more uniform distribution throughout the field.
- Environmentally friendly – Fertilizer is not scattered on the ground, and therefore is not washed away and does not pollute the groundwater.
- More and Better Quality Crops – Plants get exactly the right amount of fertilizer. This means that the crop is not poisoned by excessive fertilization, and on the contrary, produces more and better quality.
- Enables separation of fertilizers – The dosing machine has up to eight channels for up to eight different fertilizers, preventing the fertilizers from mixing with each other and making an undesirable chemical reaction.
More and more farmers are benefiting from computer controlled fertigation. In a time where food is becoming scarce, they are managing to grow more and better crops, using less fertilizers. Fertigation with CMT systems has shown a 10-20% and 30-50 % improvement in crop in comparison to applying fertilizer with sprinklers and flooding, respectively.
For more information about CMT systems for fertigation – click here.
If you have any question or comments, please email me – Lior.Doron@netafim.com
Crop Management Technology director at Netafim