Originally Posted by djonkoman
ha nice, that's my uni :p (that course you're doing, does that happen to be a course with a coursecode starting with CSA? had some courses from that chairgroup dealing with stuff like this)
harvest index is just the ratio of harvested product/total biomass.
It's through a certificate platform called edX.org- The three part program is called Sustainable Food Security. In order, I'm taking crop production, systems analysis, and security & access.
so let's say you have a plant that produces 1 kg of dry, aboveground biomass. after trimming and throwing away fanleaves, stalk, stems etc you are left with 500 grams of buds. then your harvest index is 0.5.
I don't really understand how you would calculate it from start to finish, you can only calculate harvest index at the point of harvest(or afterwards), if a plant is in veg you would have a HI of 0 since if you cut down the plant at that point, you would have 0 usefull, harvestible product.
HI also depends on what product you harvest, for example if you would be interested in fibers instead of buds your HI is different for that same plant.
or if you would be making hash, and you only count trichomes as harvestible product instead of total buds including plant matter.
usually only aboveground biomas is included when calculating HI, but it could include underground as well. for example when the harvestible product is underground(like potatoes). so if you read a HI somewhere, you have to read the description well to see what exact formula they used.
I believe I've mis-worded my objective. You're correct, though. What I mean to ask or investigate are the steps, beginning to end/ gigajoule to yield. The program is very detailed but also condensed where math steps are necessary. And I don't think the math is hard but I can't visualize or connect certain steps:
600 joule per m2 per second (Clear day, middle of summer)
40 kg Co2 per HA per Hour (C3 plant, single leaf at normal temperature. 80 kg CO2 per HA per hour assimilated by a closed canopy)
Gross Assimilation Maximum (Amax) (best possible outcome without greenhouse influence or assistance)
Next remove energy spent on respiration
[hazy on this- respiration coefficient .01-.03 kg of assimiliates per kg of standing phytomass. What do I even do with that?]
Net assimilation in kg CO2 per HA per hour
[hazy again- use the assimilation here to drive growth and quantify biomass, I think? But now we've gone from joules to gigajoules per HA per Day...]
It's between net assimilation and yield that I can't wrap my brain around. So when a question like this:
"Tree biomass contains a considerable amount of core wood, that is no longer metabolically active and therefore does not require maintenance respiration. So this implies all other organs require maintenance respiration. The maintenance coefficient of the remaining active tree components amounts to 0.1 ton (CH2O or assimilates)per ton-1 (dry matter) per year. Information collected from a Douglas fir plantation in 1924 and 1983 is given in Table 1. [table given] Q. Express the maintenance coefficient in ton CH2O per ton dry matter per day.
answer with 6 decimals, e.g. 1.234567"
Is posed, my hair blows back.