Humidity sensors and probes to control your crops

Within the mechanized or pressurized irrigation methods, drip irrigation superficial irrigation stands out, especially for intensive crops and superintensive.

Mechanized irrigation is the one that needs a mechanism that generates pressure to move the water, unless the tank is at a higher height than the drippers and these are small.

What is irrigation superficial drip?

Drip irrigation is so called because the water runs through a pipe and through a small hole distributes the water to the plant in the form of drops. Fertilizers incorporated into the irrigation water can also be administered.

In the drip you can control its quantity and the time of irrigation as necessary. The distribution is made with a network of PVC or Polyethylene conduction pipes. From each one we can take lateral irrigation hoses with drippers. These drippers form a small accumulation of humid soil next to the plant that we must control in depth, to see if it covers the entire root system.

Therefore, the number of drippers will depend on the type of terrain and the type of crop, also on the size of the root system of the plant, even on the growth of these roots as the plant grows.

This bag-shaped accumulation of water is known as a wet bulb .

Esquema de riego por goteo superficial
Surface drip irrigation scheme. 1-Water tank. 2-Pump. 3-Main hose. 4-Free ground. 5-Moist bulbs around the dropper. 6-Accumulation of salts. 7-Side hose with drippers. 8-Secondary hose. 9-Sensors / probes for humidity, temperature and conductivity.

Types of wet bulbs

The types of wet bulbs depend on the terrain and the number of drippers.

In young trees that have a small root system, a dropper can reach.

If the tree is large and has the largest root system, then it is convenient to put two more separate droppers.

We can see it in the following diagrams.

You can also put a round hose around the tree with several drippers. As the tree grows, its root system increases and the drippers must be displaced from the trunk of the tree.

Depending on the type of terrain we can also have different wet bulbs. In the sandy ones they are more elongated and the water disperses to the subsoil easily. As they become more silty, they become flattened bulbs and there is a greater risk of waterlogging.

Knowing the composition of the soil is one of the key points for drip irrigation, because it influences the wet bulb and the root development of the plant. If the roots do not have moisture nearby, they will try to find it and they will lengthen according to the type of terrain.

Tipos de terreno con bulbo húmedo y salinidad
1-Free ground. 2-Sandy ground. 3-Clay soil. 4- Sensors (probes) of humidity, temperature and conductivity at different depths. 5-Wet bulb. Few salts per washing .. 6-Slight accumulation of salts. 7-High accumulation of salts.

Salinity in surface drip irrigation

One of the problems with surface drip irrigation is the accumulation of salts around the wet bulb. As the plant needs more water, either due to the type of plant or the climate of the area or the type of cultivation, intensive or super-intensive, the problem of the accumulation of salts can occur.

We have already dedicated an article to salinity and the dependency of this problem of the type of irrigation water . This and because it is a problem that is not visible, we are forced to resort to measuring humidity and salinity with agricultural humidity and conductivity probes or sensors .

Advantages of surface drip irrigation

Surface drip irrigation has important advantages to consider:

Riego por goteo en almendros
Drip irrigation controlled by humidity and temperature sensors / probes in almond trees
  • It is very effective and inexpensive. Water and energy are saved.
  • Very advantageous in young plantations with a small root system.
  • Fertilizers can be applied when convenient.
  • It is easy to repair because the drippers are visible.
  • It does not depend on the type of floor for its installation.
  • It is recommended on stony soils because it avoids drilling the ground to install it.
  • It adapts to all types of terrain.
  • Avoid excessive growth of weeds, because we water at the foot of the plant and the drip is introduced in the form of a bag, being little visible to the outside.
  • It has less evaporation than with sprinkler irrigation but more than with buried drip.
  • It is not disturbed by windy weather. The hose goes flush with the ground and can even be anchored to the ground, as we can see in the images.

Drawbacks

  • We have to move the hoses in the first years of planting as the root system enlarges, especially in woody ones.
  • It is annoying when cleaning the plantation and harvesting because the hoses get in the way of the machines.
  • You cannot see how deep the wet bulb reaches.
  • It has more evaporation than the buried one.

Importance of probes in surface drip irrigation

The probes (sensors) installed at different depths, indicate in real time the depth of the wet bulb and the conductive tendency of the soil that will indicate if there is excess or not of salts, with the corresponding damage to the absorption of the water from the plant. The salts tend to compact and make it difficult for the roots to access water and nutrients.

The humidity probes will indicate the water in the subsoil at all times and we will give the plant the water it needs and when it needs it.

To control the irrigation and the needs of the plants, probes are essential. If we do not measure the humidity and the conductive tendency, we do not control the production and the quality of the crop.

Buried drip irrigation is yet another variant of the irrigation methods to which we are dedicating this series of articles with the aim of informing all our customers and followers.

What is buried drip irrigation?

It is an arrangement of underground hoses that irrigate the crop by localized drip and therefore directly to the root system, provided that the design is in accordance with the crop. You need a good irrigation scheme and a quality pumping system.

Riego por goteo enterrado
Buried drip irrigation. 1-Water tank. 2-Pump. 3-Main pipe. 4-Free ground. 5-Wet bulb of each dropper. 6-Salts accumulated by evaporation. 7-Buried pipes. 8-Height of the pipes with respect to the surface. 9-Humidity probe. 10-Conductivity probe.

We are going to develop the advantages and disadvantages of this type of underground drip irrigation.

Advantage

  • The main advantage over surface drip irrigation is that the pipes do not get in the way when carrying out agricultural work.
  • The main advantage over surface drip irrigation is that the pipes do not get in the way when carrying out agricultural work.
  • Not so many weeds appear because the irrigation is very localized and as it is not superficial, the low-rooted grasses do not have moisture to survive.
  • The height of the hoses depends on the type of crop, ranging between 20 and 50 centimeters depending on whether they are horticultural or woody crops.
  • Irrigation is very localized in the root system of the plant, which favors the absorption of water and nutrients.
  • It has a fairly cheap maintenance because the hoses do not deteriorate as much as on the surface.
  • If the system is well installed, the land can be worked without problem with the appropriate machinery.
  • Water is saved if the humidity level is controlled.
  • Subsoil humidity probes are essential.
Bulbos húmedos en riego enterrado
Buried drip irrigation scheme. 1-Root system. 2-Wet bulb in loamy-silty and sandy-loamy soil. 3-Slight accumulation of salts. 4-High accumulation of salts. 5-Buried irrigation. 6-Depth of irrigation. 7-Humidity, temperature and conductivity sensors.

Disadvantages

  • It is not advisable for sowing, because the humidity does not reach the seeds. It can be combined with other methods in case of sowing in land with buried drip.
  • It is also not advisable in young plantations that grow with a very broad root system. In this case we must also combine the two systems, at first surface drip irrigation and later buried drip irrigation.
  • It is very difficult to know the degree of humidity if humidity probes are not installed.
  • It is more difficult to maintain the system because it is not visible. To prevent possible breakages, it is very useful to install flow meters that will alert us to possible breakages by warning of water losses.
  • It is difficult to install on stony ground, because it costs more to make the holes.

Irrigation scheme in two phases, first superficial and then buried

Goteo subterráneo
Surface drip irrigation when the plant is young and underground when it has more root system.

How can we see in the diagram when the plant is young, it has little root system and buried drip irrigation is not convenient.

1-Wet bulb for surface drip irrigation.

2-Young root system.

3-Surface pipe.

4-Two wet bulbs with two pipes because the root system is already wider and a single pipe is enough.

5-Wider root system.

6-Two surface pipes.

7-Adult root system. We can distance two pipes or install buried irrigation.

8-Moist bulbs buried.

9-Buried pipes.

10-Height of the pipes that depend on the type of crop.

11-Moisture sensors in young plants.

12-Probe deeper to detect humidity and salinity.

PlantaeAgro Team

The types of crops that are adapted to buried drip irrigation are:

  • Horticultural.
  • Woody.
  • Gardening and sports fields.

Buried drip irrigation controlled by humidity, temperature and conductivity probes

Humidity probes are essential in underground drip irrigation. Irrigation water control becomes very difficult because the wet bulb is not visible.

The control of water by probes or sensors gives us information in real time of the level of humidity of the subsoil and allows us to program the irrigation according to the needs of the crop.

The conductivity measurement evaluates the accumulated salinity with the advantage that we can correct it before it damages the plant.

The temperature of the subsoil provides us with information on the root state and helps prevent diseases.

Lechugas con goteo enterrado
Lettuce with buried drip irrigation

In the image we can see an intensive field of lettuces with very wide furrows and buried drip irrigation with three pipes per row and six rows of lettuces. The arrangement of the pipes does not impede the cultivation. The plowing and seeding tools have the dimensions adapted to the distance between pipes.

The Plantae technician inspects the plantation to assess the disposition of the humidity and conductivity probes.

Sonda de humedad en plantación de lechuga con goteo enterrado
Humidity and temperature probe in lettuce plantation with buried drip.
Sonda de humedad en lechuga con goteo subterráneo
Humidity and conductivity probe in lettuce with underground drip.
Lechugas con riego controlado por Plantae
Drip buried in lettuce plantation.

Sources:

PlantaeAGRO

Plantaegolf

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