Blog entry 2:
Interception
is close connected to transpiration. Generally, the intercepted water gets lost
mostly because it doesn’t seep into the ground but stays at the surface of the
leaf and gets evaporated. Therefore the water loss is due to the eventual
evaporation.
Methods
The interception
loss of irrigated water is usually measured by subtracting the rainfall below
the canopy form the rainfall above the canopy (Lazerjan,
2015). Another way to quantify evaporation
is to subtract transpiration from evapotranspiration (Odhiambo
& Irmak, 2015) or to compare the run off and the
seeped water with the original irrigated water. However, to measure the
evaporation, it is important to ensure that the evaporation from the ground is
excluded.
A method to measure the transpiration is the Li-6400XT
of Licor (“LI-6400XT
Portable Photosynthesis System - LI-COR Environmental,” n.d.). The advantages is that the
measurement is right on the leaf. This device is used for measuring photosynthesis
and also the concentration of CO2 and the of transpiration. By
subtracting transpiration rate from evapotranspiration rate, we get evaporation
rate. This evaporation rate still consists of leaf and ground evaporation.
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A
possibility way to measure the run off is to irrigate potters in two different
ways. On way is from above upon the canopy and the other way is directly upon
the ground of the potter. Eventually,
the amount of water which flows through the potter into a vessel will be
compared. The difference between these two methods is probably
because of the evaporated water from the leaves. It is supposed that the vessels of on-ground-irrigated potters will
catch more water. However, this methode should be implement with various
periods of time of irrigation. It could make a difference whether the
irrigation rate is small but during the whole day constant or whether the
plants get irrigated only a few times a day with a bigger amount of water.
Results
The Li-6400XT gives us the amount of water containing in the air. The results of the run off-methode will show basically
whether there is a difference of the amount of water or not. The evaporation and therefore the size of the difference is due to the different temperature
and air humidity during the whole year probably very erratic. Measuring in just
one week is too short to get results on a big scale.
Bibliography
Lazerjan, M.
S. (2015). First attempt to measure rainfall canopy interception loss,
throughfall, and stemflow in Juglans regia Linn and Cup. Sempervirens L. Var.
fastigiata in the north of Iran. Laurier Institute for Water Sciences, 9,
60–78. Retrieved from
https://www.mendeley.com/research/first-attempt-measure-rainfall-canopy-interception-loss-throughfall-stemflow-juglans-regia-linn-cup/?utm_source=desktop&utm_medium=1.16.1&utm_campaign=open_catalog&userDocumentId={34290f73-466d-413c-b069-bada6ac8d456}
LI-6400XT
Portable Photosynthesis System - LI-COR Environmental. (n.d.). Retrieved April
8, 2016, from https://www.licor.com/env/products/photosynthesis/LI-6400XT/
Odhiambo, L.
O., & Irmak, S. (2015). Relative Evaporative Losses and Water Balance in
Subsurface Drip and Center Pivot–Irrigated Soybean Fields. Journal of
Irrigation and Drainage Engineering, 141(11), 04015020.
http://doi.org/10.1061/(ASCE)IR.1943-4774.0000907
Table of
figures
Abbildung 1:Li-6400XT of Licor
(www.licor.com)
