Practically, any garden or orchard of value, in the long run will tend to have an automatic irrigation that works with pressure systems. It is the most efficient and comfortable for the horticulturist. Even if it is not present, rest knowing that the plants are hydrating with an irrigation that you have programmed yourself and that it is carried out in a religious way. This is automated pressure irrigation.

THEORY AND PRACTICE OF PRESSURE IRRIGATION 

The concept of pressure irrigation is simple. It is to provide energy to “dead water”. When we speak of dead waters, they are not those that have lost their chemical qualities and are not suitable for irrigation, but rather they refer to waters that are stagnant.

The objective of pressure irrigation is to allow water to be carried from one specific area to another that would not otherwise be possible.

Keep in mind that most of the time we have “dead water” in a reservoir or swamp, or directly in a well or aquifer. In any case, we have to solve this difference in height by providing potential energy and then kinetic energy.

 THE PRESSURE IRRIGATION SYSTEM

In order to carry out automated or pressure irrigation that allows water to be carried to any part of our garden (including the orchard), we must be clear about how this type of irrigation works and the parts of which it is formed. We are going to talk about some basics.

 FLOW

Flow comes in function of two things. On the one hand, the amount of water that the source can provide you, be it a reservoir, a well or a source connected to urban power. On the other, the amount of moisture your plants need.

It would not make much sense to size a pressure irrigation installation with a pressure and flow greater than that required by your crops. In the same way and otherwise, you cannot afford to design something that does not match the water needs of the plants.

We can see many dimensions in the flow : L / s (liters per second), L / min (liters per minute), L / h (liters per hour) and m ³ / h (cubic meters per hour). There are more ways but they are not as common.

For example, the pump that drives and provides energy to the water will be measured in L / som ³ / h. Instead, the flow rate provided by a single dripper will be measured in something that has smaller ratios, either L / h or L / min.

 DO YOU WANT TO KNOW WHAT FLOW A TAP OR WATER OUTLET GIVES YOU?

As we already saw when it comes to knowing the pH of the soil , there are homemade ways to obtain results, in this case it is not necessary to spend any money to know the flow of a water source.

We take a bucket of known measurements, or a 5, 8 liter bottle. We fill it with the tap fully open and measure the time it took to fill. We do it a couple more times and we average the times.

Imagine that you have filled a 5 liter water bottle in 10 seconds,

This tap will provide you with a maximum flow of 0.5 L / s

0,5 L / s = 0,0005 m ³ / s = 0,03 m ³ / h = 1,8 m ³ / h

THE PRESSURE

Pressure is just as important as flow. It is the base that provides movement to the flow, so that higher pressure, higher flow.

In particular and to maintain a small garden , the pressure should not concern us more than guaranteeing the minimum so that the last dripper, the one furthest from the origin of the installation and, possibly, the most obstructed, can water with the flow to the one that has been manufactured.

Keep in mind that each irrigation element provides a loss of pressure, be it directional changes, parts and valves, drippers, sprinklers, etc. To give you an idea, the minimum pressure according to the irrigation system goes in ascending order according to this classification

Drip irrigation <Drip irrigation <Sprinkler irrigation 

As for sizing , you will hear about mca (meters per column of water), bars, atmospheres and others. The kilogram is already out of date although we constantly have to hear it.

To give you an idea, the equivalent and approximate measurements are:

1 atm = 1 kg/cm²= 10 m.c.a. = 0,1 Mpa = 1 bar

Therefore, a good garden designer has to take into account all the losses incurred and to have (for a future approach). The number of pieces that the installation will carry, the direction changes, the slope, the diameter of the pipes and the total length of the installation must be taken into account. Once this is known, the appropriate calculations are made to know the minimum pressure necessary. From this, the best engine is chosen or the water company is hired, the pressure you want and need.

 WHAT HAPPENS WHEN MY GARDEN IS VERY LARGE AND THE FLOW AND PRESSURE I HAVE VERY LOW?

Well no, you won’t have to spend a lot of money to get an impressive installation upgrade, or buy very powerful pumps or a long etc.

We will use sectorization.

If it is not possible to water a garden in a single irrigation cycle (most of the time this happens), we will have to sectorize. It is an economical and very useful measure, especially when we have different species that do not solve the same water consumption.

Imagine that in SECTOR A you have a rockery garden with xerophytic species and cacti, and in SECTOR B you have a garden with herbaceous plants. Logically you will have to sectorize. The garden should be watered more frequently than the rockery.

 WHAT ELEMENTS ARE PART OF A PRESSURE IRRIGATION EQUIPMENT?

We start from an irrigation head where all the essential parts will be found for the start-up of the installation. We have a filtering equipment, the pumping equipment and, optionally, the fertilizers.

 FILTERING EQUIPMENT

We cannot forget the importance of water filtration. If it comes from a reservoir or from a well, it will often go with inert and organic particles that will deteriorate all the installed elements. Even coming from the municipal network, it comes with particles that reduce the life of all machinery.

Among the most popular filters, we can find 3:

• Ring filter
• Mesh filter
• Sand filter

Between the ring filter and the mesh filter there is not much difference, speaking in terms of user, and both are used for the same water sources. Instead, the sand filter is used when the water is very dirty and has many suspended particles.

 PUMPING EQUIPMENT

We already have half of the pumping team talked about. It is influenced by both pressure and flow. However, there are many things to consider when choosing the best pumping equipment, which is why, in most cases, you will have to call on an expert.

Within the pumping group, either electric or by combustion, we can find the following types:

VERTICAL PUMPING EQUIPMENT

They are not the most common, but they have a very interesting application. Extracting water from wells or underground and narrow environments. They require a high lift height, especially for deep wells, where they are typically placed in series.

HORIZONTAL PUMPING EQUIPMENT

Either because there is a reservoir or because the water that comes to you from the hydraulic company does not have enough pressure to water your garden, you will need a pump of this type. They are horizontal, as the name says, and can be installed in series or in parallel.

 CREDITORS OR FERTIGATORS

If we have a localized irrigation system, a good idea is to have a fertilizer spreader at the head , in case one day we want to apply some fertilizer that is evenly distributed throughout all the outlets. It is an element to consider if we want to avoid having to pay all the plants in our garden or garden individually.

 THE DISTRIBUTION NETWORK

This part is also very interesting. Once we have the iron head with everything ready, it is time to distribute all the pipes, PVC (polyvinyl chloride) or PE (polyethylene).

Well, we have said these two because they are the most common, cheapest and most efficient , but that does not mean that you can choose other materials that are on the market.

 WHEN IS ONE OR THE OTHER USED?

The ones that you will see normally, removing the exudative irrigation , which is a special porous material, are the PE pipes . These are the small diameter ones (less than 30 mm), which can be bent and have a soft touch. For larger diameter pipes, those that are located in the head and form the primary or secondary pipes, are usually made of PVC (diameters of 50 mm or more) and are usually buried in trenches. If not, they need a special paint to protect them from the sun.

 OTHER ELEMENTS OF THE INSTALLATION

Although this article is already getting long, we cannot go without talking about the pieces that are also part of the pressure irrigation installation .

In this part we can find elements such as threaded joints, connectors, multi-piece links, plugs, T, elbows of different angles, etc.

Among other more specialized pieces there are also suction cups (evacuate or introduce the air inside the pipes, to avoid overpressure or depression), valves to avoid or reduce the passage of water flow, pressure and flow meters (manometers), etc.

 WAIT… WHAT ABOUT DRIPPERS, SPRINKLERS AND SO ON?

Sure! We forgot a fundamental part of the installation. We have the irrigation head, all the important parts, the filters, the pumping equipment, the spreader, the distribution of pipes, etc. And we have no water outlet!

They are known as emitters and we can find them in a thousand and one ways, shapes, sizes and colors.

 DROPPERS

The best known are drippers, and they have different flow rates, depending on where we place them for herbaceous or trees. There are 3, 8 and up to 16 L / h, including dripper rings to surround a large tree and homogenize the wet bulb in an ideal way.

We can find 3 types :

• Integrated: you buy them like this and there is nothing more to do. They have a previously set separation so they are ideal for a homogeneous extension of plants.
• Inserted: where you want to put a dropper, you cut the pipe and insert them.
• Pricked: by means of a skewer or punch, as it is known in slang in agriculture, a hole is made and the dropper is inserted.

But then, to add more complexity , we find those that are regulated based on the pressure and not only on the disposition, as we have seen.

• Self-compensating: the flow hardly changes
• Non-compensating: the flow output depends on the pressure in the pipe.

 SPRINKLERS

 If you want to know this system and look at it from another point of view, here is a link to an article of ours  where we tell the peculiarities of this form of irrigation that is so similar to that carried out by nature.

 EXUDATIVE IRRIGATION

Little can we say that we have not already said about this modern irrigation system . In order not to repeat ourselves, we leave you the link so that you can take a look at it. Highly recommended!