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Old 09-24-2018, 12:25 AM #701
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Old 09-24-2018, 03:56 PM #702
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another nice pic that needs rotation buddy !!!!
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Old 09-24-2018, 06:15 PM #703
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Seriously...




Colas for days. Nice Doka.
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Old 09-24-2018, 06:49 PM #704
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I've started online courses for crop production through Wageningen University.

Having some difficulty understanding a linear path to calculate harvest index from start to finish. Is it cool if I throw some non-mix/nutrients type ideas and questions out here? I'm close to cracking this but I'm missing some connecting pieces. Maybe people can spot flaws in my thinking or math.

If we're keeping this thread to soils/mixes/testing, I can respect that. I'm asking more chemistry/mathematics questions on this one....
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Old 09-24-2018, 07:23 PM #705
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Originally Posted by bsgospel View Post
I've started online courses for crop production through Wageningen University.

Having some difficulty understanding a linear path to calculate harvest index from start to finish. Is it cool if I throw some non-mix/nutrients type ideas and questions out here? I'm close to cracking this but I'm missing some connecting pieces. Maybe people can spot flaws in my thinking or math.

If we're keeping this thread to soils/mixes/testing, I can respect that. I'm asking more chemistry/mathematics questions on this one....
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.

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.
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Old 09-24-2018, 08:26 PM #706
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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.

Quote:
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
-maintenance respiration
-growth respiration
-photorespiration

[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.

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Old 09-24-2018, 09:45 PM #707
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Quote:
Originally Posted by bsgospel View Post
I've started online courses for crop production through Wageningen University.

Having some difficulty understanding a linear path to calculate harvest index from start to finish. Is it cool if I throw some non-mix/nutrients type ideas and questions out here? I'm close to cracking this but I'm missing some connecting pieces. Maybe people can spot flaws in my thinking or math.

If we're keeping this thread to soils/mixes/testing, I can respect that. I'm asking more chemistry/mathematics questions on this one....
Soil management is chemistry and simple math my friend !
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Old 09-24-2018, 10:03 PM #708
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Quote:
Originally Posted by bsgospel View Post
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.



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
-maintenance respiration
-growth respiration
-photorespiration

[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.
I find it extremely problematic to find a single group or single formula or logic to apply to varying plant species, so many unique variables it’s like trying to explain the stock market or human conscious with a single formula. But shit, Einstein came up with a damn simple one for energy didn’t he...

Some interesting pieces above you could apply though for sure. What about variables like weather, bugs, poor inputs, farmer skill, effort etc...

Are you attempting to actually do this, measure and get value, or just for the class? Decades of measurements for any real value I’d bet.

I’ve always thought it to be a hell of a lot easier to pop the seeds then listen to the plants knowing the unknowns will keep me on my toes every year, and every year is unique. Some years are great for toms, cucs, peppers and peaches, next year might be apples, pears, root veggies and so on, some are tough on everything.

Too much or too little rain / weather is by far the biggest item every year for everything.

Measure quality and weight by acreage by plant species tied into profit margins for each, what else really matters when all said and done ?
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Old 09-25-2018, 12:03 AM #709
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So, the class is revolving around core principles of ecology.

First tier is Potential Yield: If you have ideal climate and ideal genetics, these represent the absolute best you can do. You can't have a crop without assimilation of CO2- and your environment has everything to do with this. Maximums and efficiencies have been gathered across all main crops, across the globe. If you aren't fixing CO2 or assimilates to the best of your genetics ability, then you're leaving potential on the table and no water or nutrition can make up for that. In parts of the world where greenhouses, nutrition, and water are no issue and the yield gap between real harvest indexes and projections is small, the next step is to continue breeding for varieties which make the most of storage organs or sinks and use all light and assimilates even more efficiently.

Second tier is then limiting factors, Water and Nutrition: Doesn't really apply to many of us but in parts of the world where yield gaps are high, the breeding takes a backseat to amending the land and providing nutrition.

Third tier is then weeds, pests, human factors/errors, molds, preventing loss and overcoming incidental packaging wear and tear.

So where I'm at to begin is setting a baseline- if everything were perfect, what is the net result of best possible gigajoules and best possible CO2 at the optimum temperature. And there is a way, they have answers for "What was the annual growth rate of the plantation in both years if the gross assimilation rate was 43 tons (CH20) ha-1 y-1 (dry matter per ha per year) in 1924 and 31 tons (CH20) ha-1 y-1 (dry matter per ha per year) in 1983, assuming CVF equals 0.7 g (prod) g-1 (CH20).
answer with 1 decimal" - I'm just not in the groove, yet/I need to re-write all my notes and figure it out. I swear I watched each lecture 4 times and I wasn't prepared to answer these. Must dig deeper....

It's funny you say decades of measurements- they have a crop simulator which contains data from like 10 different crops in seven different countries over the last 25 years or something. You input the country, the crop, the year and the planting date and it shows you the tonnage of potatoes in Poland from 2010, planting on day 105- and broken down by storage organs, stems, leaves, and roots. It's really damn cool.
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Old 09-25-2018, 12:21 AM #710
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Here's a start- Just under Fig. 1

https://www.ncbi.nlm.nih.gov/pmc/art...7462/#MCR238C2
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