Crop production model - Units

Hello.

I am currently using the InVEST crop production model. I was wondering about the units of the nutrients associated with each crop. I am still not sure if the units are tons/year/ha, or metric tons per pixel per year, or nutritional units such as g, mcg, and KJ. I would appreciate if you could clarify.

Thank you very much,
Angelica

Hi @angelica,

According to the Users Guide it looks like units of nutrients are in kilograms/hectare. I’m pulling this from the Users Guide section: Crop Production — InVEST documentation.

I couldn’t find a reference for whether the application rate was annual or not. I’ll report back here if I can find that information.

Best,

Doug

Hello.

Thanks for your reply. Are you referring to this section in the user’s guide?

“To run this model, the user must provide an additional table that corresponds crops with nitrogen, phosphate, and potash application rates (kg/ha) per crop. The model produces modeled and observed crop yields, as well as nutritional value”.

However, I am referring to the results returned from the crop production percentile model (the csv file). I think that the units “kg/ha” in the snippet above is referring to the fertilizers applied in the regression model.

Ah, sorry I misinterpreted your question.

The raster outputs represent the production rate of that crop per pixel in metric tons per pixel per year.

The table aggregates are sums of those rasters, so they should be metric tons per year. Area is also given in that table, so one could calculate metric tons per hectare per year.

Does that help clear things up?

Doug

Thank you, Doug!

Sorry, I still have the question regarding nutrients associated with the crop, like observed vitamin K, protein, zinc, selenium, etc. Are those also metric tons per year? Initially, I thought that the nutrients associated were either in grams or micrograms (depending on the macro/micronutrient) per hectare per year.

So for example, my results from an area of 6,131 ha show production of 28,765 metric tons of apples, and 569,538,878 units of Vitamin K per year. Are those metric tons as well? It seems a lot.

Thank you,
Angelica

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Hi @angelica,

I was able to reach out to one of our science leads on this model and they indicated the following for the nutrient output units:

Protein, Protein (N x 6.25) g
Lipid, Total lipid (g)
Energy, Energy (kj)
Ca, Calcium (mg)
Fe, Iron (mg)
Mg, Magnesium (mg)
Ph, Phosphorus (mg)
K, Potassium (mg)
Na, Sodium (mg)
Zn, Zinc (mg)
Cu, Copper (mg)
Fl, Fluoride F (mcg)
Mn, Manganese (mg)
Se, Selenium (mcg)
VitA, Vitamin A (IU)
betaC, Carotene beta (mcg)
alphaC, Carotene alpha (mcg)
VitE, Vitamin E (alpha-tocopherol) mg
Crypto, Cryptoxanthin beta (mcg)
Lycopene, Lycopene (mcg)
Lutein, Lutein + zeaxanthin (mcg)
betaT, Tocopherol beta (mg)
gammaT, Tocopherol gamma (mg)
deltaT, Tocopherol Delta (mg)
VitC, Vitamin C (mg)
Thiamin, Thiamin (mg)
Riboflavin, Riboflavin (mg)
Niacin, Niacin (mg)
Pantothenic, Pantothenic acid (mg)
VitB6, Vitamin B6 (mg)
Folate, Folate total (mcg)
VitB12, Vitamin B-12 (mcg)
VitK, Vitamin K (mcg)

Let me know if you still have questions related to all this. We’ll look to add more useful information to the Users Guide as well.

Doug

That is what I thought. Thank you, Doug!

And just to make sure, the csv table gives the output per year, right? So going back to the example, it means that I have 569,538,878 mcg of vitamin K in a year? Or 569,538,878 mcg of vitamin K per hectare per year?

I appreciate all your help,
Angelica

Hi @angelica,

I believe that outputs are per year, yes. However, I don’t think they are modified to hectares, so 569,538,878 mcg of vitamin K in a year, is the right way to read those results.

Hopefully that makes sense with the numbers you are seeing!

Doug

Yes, that makes sense now! Thanks again for all your help, Doug.

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