Soil moisture sensors. Is it really worth
it? Today, everybody is speaking about soil
moisture sensors, but what is it for? And more importantly,
is it a depreciable investment? If you want to know the answer to these
questions, stay with me in this video. Soil moisture sensors We will first explain what a humidity
sensor is. This is a probe that determines:
The volumetric water contain of a soil. Electrical conductivity.
And the temperature of it. To get a better idea,
this is a kind of tube that we are going to
bury into our farm, and it has sensors at different depths. Normally,
the sensors are every 10 cm, and we can
purchase different size of probes, depending on
the depth of our root system in our crop.
For example, if we have trees with a very deep root system, we can install sensors
up to 1.2 meters length. But if the root system in
our crop is smaller, we can install, for example, a 30
cm sensor. And what is the use of this information?
The first thing we are going to know is how much water there is in our soil
and how it is distributed in the profile of the soil.
We are also going to have information of
when this quantity reaches the limit of field capacity, or the permanent
wilting point, that I had already explained to you in a
previous video. You can click on the link here.
This information will allow us to take many decisions regarding irrigation
management (length and frequency), such as:
The moment to start the pump. We can tell our control unit to start the
irrigation pump whenever the water percentage reaches a
certain value. When to stop the pump. Likewise,
we can tell our control unit to stop the pump
whenever the probe sends us a certain humidity value at
X depth. If the salt contained on the ground is too high and we have to
do a washing irrigation, also can be an information received from
the probe. As you can see, there is a lot of
information that we are going to receive, but on top of everything there are a lot
of decisions that we can take and make based
on that information. For example, did you know that
if we exceed the field capacity, and the soil is saturated on water, the
root activity of the plant will be reduced, and it
becomes in a lower water suction rate? That is to say, when we have more water
on the soil, the plant absorbs less water. Amazing, eh?
Ok, I understand that all this kind of information
is not easy to interpret, because in the end what we´re going to have are
graphics. That way, we always recommend having the
support of an agronomist or some technical advice coming from
someone capable of understanding them and
drawing conclusions. It is also a matter of
getting used to working with them, as with
everything, the more time you spend with the probe in your farm,
the better you will understand the performance of your crops
based on the information provided by the sensor.
But believe me, if you want to have full control of your crops, and reduce
as much as possible: The waste of water. The fertilizer.
The pumping energy (so any volume of water that
isn´t pumped, either). And avoid also the pollution the soil.
The definitive solution is the humidity probes.
And now, if you want to know how to install
a humidity sensor, follow me. Here we are, we have come to the
countryside to show you how to install the sensor
in the field. But first, I would like to put you in context.
We are on a newly planted pistachio nuts farm,
of the variety kerman. The total surface of the farm is around
7 hectare, and the type of soil, is a sandy-clay soil.
A while ago, this farmer never considered to plant
any crop on his farm, because of the lack of water.
Just to have an idea, the average precipitation in this area
did not reach more than 350 mm,
more or less. While he can obtain from his well
around 150 mm per year as well. The needs of the pistachio are
around 700 or 750 mm per season.
As you can see, the water margin is quite tight.
But this farmer made his calculation and decided to go forward.
To achieve his goal, he installed a subsurface
drip irrigation system, together with an automated control system.
And now, it´s the moment to install the moisture sensors.
All these elements will allow him to have
total control over the irrigation system and reduce as much as possible
water waste. Indeed, he expects to have nice yields in
this farm now. Just imagine, he changed from one
situation in which he did had no crops in this farm,
to another one, in which he expect to have nice
incomes from this orchard. Let´s see now how to install the sensors.
The first step is to determine how many sensors we need to install
in our farm. And there are three parameters that will help us
to do that. The first one, is the size of the farm.
If our farm is quite small, we can eventually install a single sensor and
it will be representative of the total surface of the farm. But instead of that,
if our farm is too big, we will need to consider installing
many sensors. In this case, we will install
only one. The second one, is the crop. If we have different crops in our farm,
with different water needs, we will need to install, at least, one
sensor for every type of crop. And the third parameter, is the type of soil.
If we have different texture in our soil, in our farm,
we will need to install one sensor for every type of soil.
The second step is to decide the location of the sensors.
At the macro and micro level. In terms of macro level, we need to
consider an area that is representative of the
average of the farm. That means, we do not
take the higher point on the farm that will receive most commonly less
water from the irrigation, as well as from
rainfall. And we will not choose the lowest point on the farm,
that will receive most commonly more water,
either from the irrigation system or from
rainfall. In terms of micro level, we need to choose one tree that is also
representative of the average on the farm. That means, we will not
choose the most vigorous one and neither
the less vigorous of them. Perfect! We choose this area because
it is the most representative of the farm. It´s not the highest
side of the farm nor the lowest. In this area,
we think that this tree is the most representative one
of all of them. Now we will speak about the tools and materials we will use.
The first one is the radio terminal. This terminal will be connected to the
sensor and will send the signal to the control unit.
The second one is the sensor itself, with all the cables that will be connected
to the terminal. And the only tool we will use in this case
is this auger, to make the hole. OK, the first thing we
will need to do is a hole, in order to find where the dripline is
and to determine where is the dripper is. We have a dripper just here.
So we did measure 75 cm, that is the spacing between drippers and we
determined, the next dripper will be here. Then,
we moved 20 cm away from the dripper,
and 60 cm away from the tree. That will give us the place in which we
will have the sensor on the wet bulb and in
the future will be in the root system of the tree as well. We dig the hole
on the selected point. After that, we need to introduce the
sensor, very carefully, until the end.
And then, we will prepare a mixture of fine soil, fine earth
and water. This mixture will help us to fill all the spacing
between the sensor and the soil.Just consider
that to perform well, to give us a good reading of the humidity on the soil, the
sensor should be in total contact with the
earth. Then we connect the cable to the meter, and
we fix the emitter on the pole. Now, thanks to the subsurface drip
irrigation system, the automated control, and the humidity
sensors, this farmer is ready to grow profitable
pistachios in his farm. A farm he used to think it
was unable to grow anything. If you have a farm,
and you are interested in getting advice on how to improve
your yields, just do like this farmer: send us an email. Our team of
specialists will visit you to offer you advice.
Your farm could be the starring of our next video! Soil moisture sensors
