far to high DeadWLeaf

[Christof Kluß]

Hi

can someone tell me the source (literature) of the dead leaf weight algorithm?
(Can I reduce this matter without changes in the other yields?)

It seems to be calculated as

DeadWLeaf += WLeaf * 0.333 * CAImRat

with
CAIm = - log (PARrel) / PARext
CAImRat = max (0, (CAI - CAIm) / CAIm)
PARrel - PAR reflectance (should be about 0.06 for maize)
PARext - PAR extinction coefficient (should be about 0.6 for maize)

I get far too much dry matter and nitrogen yield for dead leaves (all other "fractions" fit quite well)

Greetings
Christof

[Per Abrahamsen]

Hi Christof.

You can easily decrease dead leaves yield by increasing the ExfoliationFac parameter, e.g.

  (ExfoliationFac 1.00)

in Prod. Basically, it will make the dead leaves drop down to the ground, where they will be incorporated in the soil by earthworms.

Regards,

Per

Christof

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[Christof Kluß]

Hi Per

excuse me for the very late reply. That will solve the output, but I think, that it will not solve the problem. When I do not want dead leaves at all (or very few) there is no direct way to influence this, correct? (In Maize we have substantially less dead leaves, as simulated. We measured this every 1-2 weeks ... of cource we will have an error because dead material can fall down, but it should not be so high)

If the earthworms eat the "pseudo-dead" leaves... will there be an influence on the soil model?

I am very interessted to understand such details and not "only" the rough description like in your very good articles like
"Modeling Water and Nitrogen Uptake Using a Single-Root Concept: Exemplified by the Use in the Daisy Model". (Just because Daisy is so well documented in principle, that almost no other similar complex model can say of itself. ;))

Best
Christof

[Christof Kluß]

Hi Per,

to make the problem clearer, a graphic. There are more dead Leafes than living leafes, but in our measurements the dead leafes mass is near to zero.

Of course (ExfoliationFac 1.00) will make the graphic better, but its a pity that you can not realy turn off the dying, everything else fits pretty well already without adjustment. ;)

thx

Christof


Am Mittwoch, 3. April 2013 10:40:17 UTC+2 schrieb Per Abrahamsen:

[Christof Kluß]

[Christof Kluß]

the plot