We are currently working on a sensoring system which measures soil humidity, temperature, nitrogen, phosphor, potassium and ph level. We are trying to stimulate the efficiency of farming and support local farmers. One of our problems is that we are able to measure the level of humidity in percentages but this does not help farmers enough. Our advice is not accurate when we just compare the level of humidity of different farming fields and do not account for other factors like rainfall, temperature/humidity of the air and maybe even other factors like different crops. My question is: is there a formula that is able to calculate which farming field would need irrigation the most. We would like to be able to calculate every field and give a ranking which field would need irrigation the most, we think this way we could help save water and also stimulate the food supply.
If you think you could help me any way feel free to respond on this post or send me a direct email on [email protected]. Thank you in advance!
Dear Morris,
I'd probably advise to develop a composite index comprimising of at the least the following parameters:
1.) Absolute and relative humidity of ambient air (at ~ 2 m height)
2.) Near-surface soil humidity (~ - 1 cm) - both absolute and relative (if possible in your set-up)
3.) Absolute and relative (again, if technically possible for you...) soil humidity at the lower basis of the A[h] horizon (depending on where you work at perhaps ~ - 30 cm)
4.) Air temperature
5.) Soil temperatures at depths indicated above
6.) Amount of precipitation over last 24-48 h
7.) Evaporation + transpiration = evapotranspiration rate
8.) Duration of sunshine exposure over last 12-24 h
9.) Amount of water/irrigation rewuired by the crop grown (based on statistical data)
Of course, you can weigh the different parameters depending on your specific needs and local conditions.
Best,
Julius
Many factors influence the amount of water consumed by plants. The more important natural influences are climate, water supply, soil, and topography. The climatic factors beheved to have the greatest effect on consumptive use on which data are generally available are temperature, precipitation, humidity, wind movement, and growing season. Irrigation practices, as wefl as kind of crops grown, their stage of growth, and species, also influence the amount of water consumed.
In such cases the irrigation water need (IN) is the difference between the crop water need (ET crop) and that part of the rainfall which is effectively used by the plants (Pe). In formula: IN = ET crop - Pe
. Estimated seasonal consumptive use in inches can be computed from the formula
U=KF
Where U=use of water in inches;
K=empirical seasonal coefficient;
F=sum of the monthly factors (f) for the season (sum of the products of mean monthly temperature (t) in degrees Fahrenheit and monthly percentage of annual daytime hours (p)). The equation for monthly or short-period consumptive use in inches is u=kf
A great question, just in case you've not already seen it, FAO 56, Allen et al, 'Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56', is worth looking at as it includes details of key environmental drivers and the use of crop coefficients.
Soil moisture sensors can be applied to avoid over watering and poor WUE as well as under watering leading to plant stress - specific moisture levels will be dependent on crop and soil type.
- Badges
- Science topic
- Similar topics
- Agricultural Science
- Agronomy