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APSIMInitiative / APSIM710

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APSIM Rotation Managment Question #2183

Open s-aagarwal opened 1 year ago

s-aagarwal commented 1 year ago

I followed along with the Creating a Wheat Lucerne Rotation in APSIM tutorials (https://www.apsim.info/support/apsim-training-manuals/crop-rotations-in-apsim/). Everything worked fine, but I have this one question about it. In the image I attached below I was wondering what was the point of having 2 arcs attached to the Lucerne node. Doesn't canLeave already check for whether the crop is harvestable or not? I was also wondering in general why you would want two arcs coming out of the same node. The image is attached below.

Crop Managment tool

peter-devoil commented 1 year ago

Inside the logic of the "Lucerne Ley Management" component is code to harvest (the crop continues regrowing), and to leave, which harvests, and then kills the crop. This code is hooked up to the actions/events in the rotation manager.

The "canLeave" logic doesnt test whether the crop is ready for harvest, it tests for a) whether the crop is alive, and b) whether the length of time that the crop has been in is greater than the number of years in the ley. So while the rules terminology (leave/enter) is similar to annual crops, the actions for perennials are subtly different.

Looking at the output file shows several harvests, followed by a wheat crop.

s-aagarwal commented 1 year ago

ok so in this case I noticed that the lucerne crop is being grown for 10 years straight and that it always has a crop yield of zero. Based on what you told me I assume that this is because the crop never got officially harvested since the harvest action just made the crop regrow. Also after 10 years, the crop had been in long enough so the leave component then killed the crop. Just clarifying whether this was right or not.

peter-devoil commented 1 year ago

Lucerne is harvested at flowering (for forage), so the grain component (yield) will be zero. The biomass (leaf & stem) should be +ve.

s-aagarwal commented 1 year ago

ok, thank you so much for clarifying. My last question would be why we have this extra arc under the lucerne node checking for harvest, but not under the wheat node.

peter-devoil commented 1 year ago

Wheat is an annual crop harvested for grain and immediately ploughed in afterwards.

Lucerne's a perennial that is harvested for forage ~5-10 times/year, and ploughed in after 10 years.

So the extra arc is the forage harvesting, and as wheat isnt harvested for forage, it doesnt need that operation.