How to make automatic watering in a greenhouse

Recommendation points

• Storage tank: how much plants drink
• What watering methods can be automated
• Main pipelines
• Automation equipment
• Field trials

Watering takes almost a third of the gardener’s time. It is tedious and not always possible. But time does not stand still, and technologies are actively developing. We suggest organizing an automatic irrigation system in your greenhouse. Let’s look at the equipment and automation schemes for irrigation.

Storage tank: how much plants drink

For most plants, it is optimal when alternating wetting and drying of the soil occurs during the day. Plants in this mode receive water in a timely manner, at the same time, unhindered reproduction of pathogenic organics does not occur in the soil. What is really important for proper irrigation is the presence of loose soil and its timely aeration, the rest will be handled by an advanced automatic irrigation system.

The irrigation rates for each specific crop are indicated by the seed producer. For cucumbers, this is about 10-15 liters under a bush every third day, adult fruiting tomatoes are watered by 30-35 liters, but only once a week. The amount of water is determined by several more factors: temperature, air humidity, growth period and genetic characteristics of the variety..

Another key parameter is soil wetting depth. You should be reliably aware of the time it takes for water to seep deep into the soil by 20 or 50 cm for different crops, without having time to dry out. We are talking here about both the throughput of the irrigation system and the type of soil, the method of irrigation (rain, drip, subsurface) and the desired sizes of wetted areas, individually for each bush or for the entire garden as a whole..

Based on the amount of water consumed, you will determine the amount that should be applied to the soil over a certain period of time. Considering that it takes about 10-15 hours for the soil to dry out, this amount can be divided into several stages, if in each of them the soil has time to get wet to the required depth. A similar calculation must be carried out separately for each bed or group of beds that require a one-time application of water in the amount of 150-200 liters. A tank of such a capacity must be installed under the ceiling of the greenhouse, in the case of water intake from a well or well, it is necessary to embed a heating element with a thermostat into the container.

What watering methods can be automated

In principle, any droppers, sprinklers and foggers can be operated automatically. A completely different question is exactly what kind of irrigation your crops need. In general, we can say that the introduction of water under the stem by the drip method is preferable for absolutely all types of plants and is the main source of moisture for them..

Sprinkler systems are used as a method of creating a suitable microclimate for the legume and pumpkin family – many varieties are very positive about moisture on the leaves. At the same time, a constantly waterlogged atmosphere and drops of moisture provoke the rapid development of late blight on crops of the Solanaceae family, although periodic crown moistening is simply necessary for some varieties.

Fogging agents are indispensable for growing flowers, spicy and medicinal herbs, for which dry air is destructive. In general, fog systems are included in a separate humidification system, although you will soon see that they can also work as part of a main irrigation system..

Main pipelines

The essence of the main wiring is simple: with a 32 mm HDPE pipe, it is required to extend a line along key points that serve as the beginning of individual irrigation areas with a one-time discharge of water comparable to the tank capacity. This requirement is due to the logic of the system’s operation: the filled container is drained to irrigate a specific area, then the existing pipeline branch is closed, the container is refilled, the water is prepared (heated, fertigated) and discharged into the next irrigation sector – everything according to the established schedule.

The change in the direction of flow in the system is carried out by switching the electric valves. At least one of them must be installed at each line connection point. By the way, the more branches you have from the line, the easier and more accurate you will be to regulate the amount of irrigation water. In other words, no one bothers you to empty the tank on the same area several times, or vice versa – to water several from one container at once. Please note that over time, the irrigation calendar can change significantly, the described system is capable of operating non-stop, watering something all the time.

From each electric tap, a branch pipe with an internal diameter of 20 mm or so is extended along the irrigation area. It is used to cut in fittings or piercing fittings of irrigation fittings. These can be drip tapes, flexible tubing, or rain sprinklers..

Difference of sprinkling and fogging systems from drip systems in high working pressure. Accordingly, it will be necessary to supply the piping with a pump of 150-200 W and think over its switching with a mini-contactor.

Automation equipment

An electrically controlled shut-off valve will be the most expensive purchase for a greenhouse. The average price of an electric ball valve with fittings for HDPE will be from 2 thousand rubles and more. But there is always an opportunity to get by with more budgetary funds:

1. Tee HDPE 32 mm with 3/4 “female thread – about 100 rubles.
2. Electromagnetic valve for washing machines – up to 300 rubles.

The problem with these valves is that their outlet is a fitting for a rubber or silicone tube with an internal diameter of up to 10–12 mm. Perhaps it makes sense to install such a reinforcement for every 8-10 bushes, followed by laying a garland of calibrated droppers. The same tube can be used to connect one drip tape up to 20 meters long. Even in a greenhouse with an area of ​​up to a couple of hundred square meters, a dozen of such valves will be enough to automate irrigation..

In larger greenhouses, solenoid valves in a plastic body with a 1/2 “female pipe thread at both ends can be of great help. Such valves can already be installed at the beginning of each branch from the main, but their throughput is not too high. more than 150 liters of water at a time, which is typical for very large greenhouses, you should still install full-size valves for threaded connections 3/4 “and higher with a corresponding extension of the pipe cross-section.

Modern technology offers plenty of ways to control valve switching. The easiest for the average person is to build a system based on programmable relays OWEN PR-200. They are easy to set up and can switch up to eight electrical devices with a total power of up to 1 kW. Issue price – 6 thousand rubles.

If you take the time to study the Arduino IDE, you will master the basic principles of building a freely programmable automation complex that will be two heads taller than any typical solution. It is about drawing up daily and weekly watering calendars, which take into account not only the time of day, but also temperature, humidity and atmospheric pressure. Being a fairly low-cost platform (a board and relay modules for 16-20 devices will cost about 5 thousand rubles), Arduino makes it possible to automate lighting, ventilation, heating and irrigation water preparation at the same time.

Field trials

The installation of the system should be completed a couple of weeks before planting seedlings or sowing seeds. During this time, a number of test runs are performed, designed to fine-tune the system and pre-moisten the soil.

At each test watering, check the depth and area of ​​the soil to be wetted, if necessary, equip the system with valve regulators. Good harvest!