[REQ] Best irrigation start time according irrigation duration and weather condition

[alsmaison]

I really appreciate the possibility to define the best irrigation duration. Thank you very much for your work !

As I'm a novice, I have another need to cover. At what time I need to start irrigation and do I need to split it during the day in case of specific weather condition (extreme temperatures) ?

This would be a great addon if you can add also a smart feature for that.

Thanks in advance for your investigation.

[jeroenterheerdt]

interesting - how would you imagine this would work?

[alsmaison]

Please find what ChatGPT gives to me :

There isn't a single, universal mathematical formula to calculate the optimal watering time for plants, as this depends on many factors such as environmental conditions, plant type, soil characteristics, and local climate. However, a more scientific approach can be used to estimate the optimal watering time by considering key parameters.

Variables to Consider:
Temperature (T): Measured in degrees Celsius or Fahrenheit.
Relative Humidity (H): Measured as a percentage (%).
Evapotranspiration Rate (ET): Measures the amount of water evaporated from the soil and transpired by plants, typically in mm/day.
Light Intensity (L): Measured in lux or watts per square meter (W/m²).
Soil Water Retention Capacity (C): The amount of water the soil can hold, expressed in mm or as a percentage.
Estimating the Optimal Watering Time:
A simplified approach could use these variables to estimate the best time of day based on minimizing evaporation and optimizing water absorption by plants. An empirical formula might look like this:

Optimal Time

Adjustments and Complexity:
Arid Regions: If the ET is very high (in arid climates), watering should be done early in the morning.
Seasons: In summer, higher temperatures and evaporation rates mean the optimal time will be earlier compared to winter.
Plant Type: Deep-rooted plants may need watering at different times compared to shallow-rooted ones.
Conclusion:
While this formula may offer an estimation, it is important to test and adjust it based on local conditions and specific observations in your garden. The most reliable approach remains observing the plants and environmental conditions to adjust watering accordingly.

I read also that the water can be made between Point de Rosée and the beginning of the sunshine. It could be interesting to see if the formulat gives by ChatGPT is somewhere around.

[alsmaison]

To define if you need to split your daily water, it could be interested to define maximum water soil capacity. Here is the ChatGPT answer :

there is a formula to estimate the amount of water that soil can absorb before reaching saturation. This quantity depends on the physical properties of the soil, particularly its water retention capacity, depth, and current water content.

Variables to Consider:
Field Capacity (FC): The maximum amount of water the soil can retain after drainage, expressed as a percentage (%) or in mm/m.
Permanent Wilting Point (PWP): The moisture level below which plants can no longer extract water, expressed as a percentage (%) or in mm/m.
Soil Depth (D): The depth of the root zone or the soil layer in question, usually expressed in meters (m).
Current Soil Moisture Content (θ): The amount of water currently in the soil, expressed as a percentage (%) or in mm/m.
Formula to Calculate the Water Amount Before Saturation:
The amount of water that soil can absorb before becoming saturated, denoted as

Adjustments:
Soil Type: Clay soils have a higher field capacity, while sandy soils have a lower capacity. Field capacity is strongly influenced by soil texture.
Soil Condition: If the soil is compacted, it may have reduced water retention capacity, requiring adjustments to the values used.
Conclusion:
This formula allows you to calculate how much water the soil can absorb before reaching saturation, based on its physical properties and current moisture content. It’s a useful tool for avoiding overwatering and preventing drainage and soil saturation problems.

As we can find soil sensor, I think this is possible to apply the formula. Do not hesitate to ask chatGPT to have calculation example (I give you an extraction of it answer)

[alsmaison]

for the hour regarding the Rosée period, you can use the formula describe by ChatGPT :

Here’s how to calculate the exact time of dew formation: (when you have the Dew Point)

This will give you an approximate time for dew formation. Adjust this method based on specific local data and current weather conditions.

Conclusion
The exact time of dew formation is calculated by determining the dew point and modeling the nighttime temperature decline to find when the temperature reaches this point. Results can be adjusted based on local variability and conditions.

[jata1]

wow - there is a lot to consider here. Good research by the way. Thank you and chatGPT too.

What I do is this.

1. use the already working smart irrigation to work out the total watering duration for the day
2. water in the morning before dawn in most cases
3. when it is very hot, watering duration is quite high so I split the watering total with half duration at dawn and the remainder after sunset

[jlrosssc]

All of the research I have done indicates that you are better to water in the morning. I am currently looking at the total requirement and have a condition to use the watering time value as is or divide it up into two or three equals segments with a soak-in time in between. With the new soil saturation parameter included, it should be able to fairly easily incorporate that into the logic so that it does not water beyond the saturation point of the soil without introducing some, soak in times.