Back to Progress

Implementation of the irrigation head for pure CO2

The present document is a summary of deliverable DC2.1 which corresponds to task C2, Agronomic Study and Component Selection. It contains all the information relating to implementation of the irrigation head for pure commercial CO2 dosing in the initial selected plot (plot nº 1) and in the new and final selected plot under study (plot nº 2). All the agronomic values for the correct implementation and the necessary adjustments in the irrigation head have been determined.


Plot nº 1 was selected prior to the beginning of this task. The adjustments needed to adapt the irrigation head with the CO2 metering system were performed. The system was therefore operating successfully so as to start irrigation.

After the beginning of the agronomic tasks included in this action C2, a more appropriate plot was found. This new plot is more conveniently located as it is nearer the ceramic installations under study (EATOMIZADO). The consortium applied NEEMO for a change in the selected plot on the 22nd of November and this one was approved on the 16th of January 2017.

It must be noted that the change in the plot has led to the repetition of tasks concerning irrigation with pure commercial CO2 in P1 and in P2. Nevertheless, the consortium is assuming the costs incurred in P1 and this fact will add more data to the study.

Therefore, at this point we have 2 plots in which the work is being carried out and defined as:

Plot nº1→ Selected plot at the beginning of the Project where the irrigation head has been adapted for commercial CO2 injection, by means of CO2 tanks, and where the corresponding agronomic tests are being carried out. The water used for irrigation comes from “Cota 220 Irrigation Community”. This plot nº1 (P1) is located in the town of Onda, at 6 km from EATOMIZADO’s facilities, and situated in plot 128 of the Industrial Estate 18. It has a total area of 3,310 m2.

To carry out the study, P1 is going to be divided into two areas: area AP1: control area where the usual agronomic works (irrigation and fertilizers addition) are going to be carried out and, area BP1: irrigation will be carried out with carbonated water with pure commercial CO2 together with fertilization. These two plot areas have been selected so as to be as similar as possible, in terms of the size and shape of trees, the soil type or leaf nutrients, in order to obtain reliable and comparable results. The crop of study is citrus, orange, variety Late Navel Late.

Plot nº2 → Selected plot a few months after the beginning of action C2, where the consortium is carrying out C2 and C3 tasks. C3 action corresponds to the injection and dissolution of the CO2 captured from EATOMIZADO in irrigation water. Plot nº2 (P2) is located in the town of Onda, at 800 m from EATOMIZADO’s facilities, and situated in plot 94 of the Industrial Estate 54. It has a total surface area of 8,751 m2 that is going to be divided into three areas: area AP2: control area where the current agronomic works are going to be carried out; area BP2: irrigation will be carried out with carbonated water with pure commercial CO2 together with fertilization; and area CP2: irrigation will be carried out with carbonated water with CO2 captured from EATOMIZADO, together with fertilization.

It must be noted that in this case, the water used for irrigation comes from a well, property of the owner’s P2. The presence of a well is one of the advantages of P2 since having the same source of water will enable the comparison of the 3 experiments to carry out in the plot: irrigation with current water, with water containing pure CO2 and water containing industrial CO2.

So, the objectives set in task C2 are being performed in both P1 and P2. And the objectives set in task C3 will be carried out only in P2.

The first part of this deliverable describes the design, calculation and implementation of the irrigation system corresponding to P1, and the second part the one corresponding to P2.

The present report on agronomic calculations is therefore drafted to determine crop irrigation needs. Water crop needs of the selected irrigation areas will determine the size and the design of the irrigation head. It is worth to mention that all the contents related to the design of experiments, sampling protocol, monitoring of the parameters as well as the results obtained from the CO2 fertirrigation will be gathered and shown in the corresponding deliverable, DC2.2, “Report of agronomic trials”.

Irrigation water needs is the difference between the crop water needs and effective precipitation, the latter being understood as the precipitation actually used by the plant for its growth or making it available for assimilation.

For the calculation of the water requirements of any crop and using the parameters of the FAO (Food and Agriculture Organization of the United Nations), parameters such as reference crop evapotranspiration (ETo) and the crop coefficient (Kc) are required.

Potential evapotranspiration (ETo) is calculated as a function of climatic variables, such as temperature, relative humidity, radiation, insolation, wind and evaporation; while the calculation of the crop coefficient (Kc) must take into account the crop itself, the phenological status at all times as well as its specific crop conditions and local climatic conditions.

The calculated annual evapotranspiration has a value of 619.22 mm/year and represents the amount of water that a crop can evaporate when it is in good water supply conditions and with the soil close to field capacity.

The actual precipitation calculated, based on the data observed at the Onda station, is 122.2 mm/month and represents the amount of soil infiltration water which remains available to the plant roots without drowning and without arriving to be lost by runoff or by deep filtration.

Thus, the net irrigation needs are obtained by the difference between the evapotranspiration of the crop and the effective precipitation and taking into account that for the type of irrigation installation used (by dripping) it is considered an efficiency in the application of irrigation of 90 %, we obtained a value of annual irrigation needs of 590.6 l/m2. This value represents the amount of water that must be supplied by the irrigation system to ensure that the crop receives all the water it needs.

Finally we have calculated the required water volumes according to the total needs for each type of irrigation surface and the surfaces of the same, obtaining that the average needs resulting, taking into account the crops is of 5,906.00 m3/ha and the total needs are up to 977 m3/year in P1 and up to 1723 m3/year in P2 for each of the areas of the plot (control and pure injected CO2).

Irrigation water in P1 comes from the Irrigation Community of Cota 220 with an assigned flow of 12.03 m3/ha and hour. This amount corresponds to the installation of two lines of self-compensating droppers per tree of 3.8 l/h per dropper and separation between 1.00 and 1.25 m according to the citrus plantation frame.

Concerning P2, irrigation water comes from a well, property of the owner’s P2 with a flow of 4500 l/h. The drip irrigation installation has two lines of self-compensating droppers per tree of 3.5 l/h per dropper and the separation distance between trees is of 1.25 m.

The irrigation head has been sized and designed according to the previous established water irrigation needs. The irrigation head has been installed in the area of study and contains the following elements (see plan 05: Irrigation head in plot 1 and plan 07: irrigation head in the new selected plot: P2):

  • Shut-off valve
  • Non-return valve
  • Sucker
  • Pressure gauge
  • CO2 tank
  • Electrovalve
  • Shut-off valve
  • Non-return valve
  • Irrigation scheduler

It must be noted that in the case of P2 the irrigation head contains the elements necessary for the irrigation with water containing industrial CO2, this information will be explained in detail in DC3.2.

All the tests that are being performed with CO2 dissolved in irrigation water are being carried out in a uniform way, that is to say, the dose of CO2 that is being injected is calculated so as not to reach pH values under 6, since lower values are not optimal for citrus crops, and may cause phytotoxicities in trees. The pH of irrigation water is being measured manually.

In P1, the CO2 flow rate that is being injected to reach pH target value is 1 l/min and 3 l/min depending on the addition of fertilizers and will be injected according to the fertilizer and irrigation schedule presented in this deliverable. In the case of P2, the CO2 flow rate that is being injected to reach pH target value of 6.5 is 7.6 l/min. The correct parameters values, such as irrigation days and irrigation time, can be adjusted with the programmer.

The following table shows the different CO2 injection sources, related actions and water origin in each plot.

To conclude, it can be confirmed that all the irrigation trials with pure commercial CO2 in P1 and in P2 are being performed successfully after the installation of the adjusted irrigation head and the CO2 injection system. Irrigation trials started in March 2016 and will end by the end of 2017 in P1. Note that irrigation trials of this task are being carried out in parallel in P2. Technical adjustments of the irrigation head started in January 2017 in P2, after the approval of the change in the plot, and ended in March 2017. Thus, irrigation trials with pure CO2 in P2 started in April 2017.

As regards deliverables, it has been decided that the present deliverable of action C2, describing the adjustments in the Irrigation Head for CO2 dosage (DC2.1), will report performing tasks in P1 and in P2. Likewise, deliverable of action C3, describing the adjustments in the Irrigation Head for industrial CO2 dosage (DC3.2), will report performing tasks in P2. These two deliverables, DC2.1 and DC3.2, give technical information of the irrigation head adjustments and components description. The description of the agronomic study, including sampling protocols and analytical determinations, and the results of the agronomic trials will be described and analysed in detail in the following deliverables expected in June 2018 (DC2.2 and DC3.3).