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БългарскиAs it turns out, heat is not the main factor, which depletes soil moisture. Besides temperature, soil moisture losses depend on the solar irradiance, wind speed, relative air humidity, etc. The indicator that take all these factors into account is called evapotranspiration. It measures how many millimeters per square meter we lose due to evaporation from the soil and transpiration from the plant leaves.
Are you familiar with these situations:
“I irrigate, but I still do not get high yield”
It is important to water according to the needs of the plants, not “on a schedule”. As the season progresses and the crops grow, evapotranspiration increases, and with it the necessary irrigation rate. For example, if at the beginning an irrigation of 15 mm/sq. m was sufficient, then in the midst of summer it often turns out that 30 mm/sq. m is needed.
“I don’t have enough water”
When designing any irrigation system, it is very important to know how much water will be needed. During the July heat, moisture loss often reaches 9-10 mm/sq. m per day. This means that a 10 ha (2.5 ac) corn field, for example, requires nearly 1000 cubic meters of water per day.
“Water is not a thing I save from”
Even if the access to water is cheap, overirrigation can also be a problem. For example, it can lead to cracking of table grapes, melons, etc. Furthermore, the excess water leaches the nutrients deep down in the soil. Not only are plants unable to absorb them, this also leads to groundwater pollution.
“It was raining, but the wheat/corn leaves are still rolled up”
If the moisture reserves in the soil decrease and evapotranspiration is high, plants begin to experience water stress. Such situations occur not only in summer, but also during “dry spells” in spring. The reason is that strong winds and low air humidity also lead to water loss. If we cannot irrigate, then in such a situation it is better not to stress the crops further with spraying and fertilizing.
The following charts from Meteobot® show that on May 2nd of this year, evapotranspiration for an automatic meteorological station in North-eastern Bulgaria was nearly 6 mm/sq. m with a maximum daily temperature of 23°C. And on May 5th, the water loss was only 4 mm, even though the maximum temperature had risen to nearly 27°C. The reason was the strong wind on May 2nd, reaching 14 m/s.
Meteobot® weather stations for agriculture calculate reference evapotranspiration (ET0) automatically, using the Penman-Monteith equation. To the standard Meteobot® Pro configuration, you only need to add a solar irradiance sensor (or the so-called pyranometer).
This year, we became a distributor for Bulgaria of the American company Apogee Instruments Inc., a manufacturer of innovative environmental sensors.
If you are a Meteobot® customer, you can order an Apogee SP-110 solar irradiance sensor (pyranometer) at the preferential price of 370 240 EUR (excl. VAT).
The promotion is valid until July 15th, 2025.
To order or for more information, contact us at info@meteobot.com or +359 896 959628