Crop growth

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epelde.ane@gmail.com
MOHID Advanced user
Posts: 172
Joined: Thu Jan 01, 1970 00:00

Crop growth

Postby epelde.ane@gmail.com » Mon Sep 09, 2013 09:53

Hi all!

I´m trying to stablish PAST itinerary through heat units but there is something I think I´m missing..

1) in a continuous simulation I´ve set HU fraction to harvest: 0.81 with an efficiency of 0.5. when that ammount is reached the total biomass is reduced from 24000to 10700. shouldnt be reduced to the half? or, harvest efficiency is only a parameter that says how much residue I leave after harvesting? In that case, the difference in biomass would be controlled with crop harvest index, right? And, is there any way of checking how much residue is left? if not, would it be: RESIDUE= (1-(harvest efficiency))* (biomass before harvest-biomass after harvest)?

2)Then, I made one year simulation to decide HU fraction value in order to have 2 harvests in a year. I saw that with 0.2 I would have 2 cuts, but when the past reaches that value it doesnt happen any harvest.. Do you think I´m missing something? maybe because it is a very low value? because in same simulation in other crops, it is ocurring harvest if I set a harvesting date..

Thank you in advance,
Ane

davidbrito
MOHID Advanced user
Posts: 189
Joined: Thu Jan 01, 1970 00:00

Re: Crop growth

Postby davidbrito » Thu Sep 19, 2013 08:40

Hello Ane,


1)
The biomass harvested is Yeld * HarvestEfficiency and
Yeld if OptimalHarvestIndex > 1:

Code: Select all

Yeld    = TotalPlantBiomass * (1. - 1. / (1. + ActualHarvestIndex))


Yeld if OptimalHarvestIndex < 1:

Code: Select all

Yeld    = AerialBiomass * ActualHarvestIndex


And the Actual HarvestIndex:

Code: Select all

 ActualHarvestIndex = (HarvestIndex - MinimumHarvestIndex) *                                                           &
                              (WaterDeficiencyFactor /  (WaterDeficiencyFactor + exp(6.13 - 0.883 * WaterDeficiencyFactor)))  &
                              + MinimumHarvestIndex


So if you have water deficiency you will got different Yeld that just multioplying biomass by efficiency. This is to mimic that if plant is drying more than expected you will not get all the biomass expected.


2) You have to check Harvest HU Accumulated (time serie result in .srv) and check that it passes on 0.2.
If it passes on 0.2 than it should harvest.
Teel me after.


Best Regards,
David

epelde.ane@gmail.com
MOHID Advanced user
Posts: 172
Joined: Thu Jan 01, 1970 00:00

Re: Crop growth

Postby epelde.ane@gmail.com » Thu Sep 19, 2013 17:13

Hi David!
Thanks for the explanations!

I have set HARVEST_PLANTHU : 0.2 for the ID occupied by PAST and accumulated HU go increasing from 0 to almost 0.4, but no reduction in accHU and neither in bomass is shown.. (when harvest operation occur, all the biomass is taken off? and accHU becomes 0?)
In vegetation file is there any keyword to activate only harvest? or is it enough with HARVEST_KILL?

Regards,

davidbrito
MOHID Advanced user
Posts: 189
Joined: Thu Jan 01, 1970 00:00

Re: Crop growth

Postby davidbrito » Thu Oct 17, 2013 13:47

Hello,

the difference between Harvest and Harvest and Kill is done in the vegetation parameters file.
The other accounting on harvest we will see with you.

Best regards,

David


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