Importance of dew is world wide recognized in rainfed agriculture. But generally we do not consider it in calculation of water use efficiency. How we can add the amount of dew in water use calculation? Kindly answer with authentic source files.
Regards
Sorry Raman I dont know. You may please ask Prof. Ratan Lal, OSU, USA. He is the right person.
Dear Raman,
Why not use a drosometer I see only this means of quantify the amount of dew deposited
With my best regards
Prof Bachir ACHOUR
Since the amount of dew is less compare to Precipitation It is consider negligible. If u want to include it for analysis you need to identify the proposition of Precipitation and Dew. Based on this you can try to derive new formula....
Established methods is not known to me. But you can conceptualized like this. Can keep container which can accumulate /deposit dew and remain in water form in early morning. Estimate the volume on average basis depends upon plot size and calculate the volume of water.
Further to Konstantin's answer. In various topographic niches in arid climates dew is a more regular provider of water for natural vegetation than rain, including the Namib desert (and probably Chilean equivalents) and some of the drier slopes in the Cabo Verde.
I find it hard to imaging that the above would apply to rain-fed crops or pastures. Not only require crops/pastures considerable more water than desert vegetation, but dew seems typical for the colder pre- or post-harvest season (at least in temperate Europe).
Dear Raman,
You can calculate Dewpoint if you know the RH and temperature of that location. For further details please go through the following article.
Lawrence, Mark G., 2005: The relationship between relative humidity and the dewpoint temperature in moist air: A simple conversion and applications. Bull. Amer. Meteor. Soc., 86, 225-233. doi: http;//dx.doi.org/10.1175/BAMS-86-2-225
Zafar
Terry Gillespie at the University of Guelph has done a lot of work with leaf wetness sensors. I don't think he ever used them to quantify dew, but his work might prove helpful. He has too many articles to list here--go to Google Scholar and search for TJ Gillespie.
My 1-cent contribution....
Some years ago I evaluated the water from dew in adult (grain filling phase) plants of black oats (Avena strigosa). The objective of that test was not related to weather or soil water content, but with pesticide spray technologies. What I did: I fully bagged the plants with a big plastic bag (~0.5 m2 each sample); the bag was closed and the plants were cut at the soil level. Immediately I weighed the bags with the plants + water (dew); other weight measure was taken in ~2 hs, after shaking the plants and waiting water evaporation. I did not disturb/touch the plants when bagging them. It was a very simple technique, but with 12 repetitions on average we measured more than 6.000 L/ha of free 'dew-water' in the leaves and culms of oats. There were a lot of water in the plants (anyone entering in the field, exit with completely soaked legs), and I believe it facilitated the measurements.
We did this measurement only for 1 day, but I believe this technique can be repeated, and the 'real' data correlated with data from formulas (used to estimate dew formation & duration), to extrapolate the accumulated water in a full-season, for example.
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