Multiple harvest time setting for lucerne

[Submarine-666]

Dear experts,

Which management modules/options concerning the alfalfa sowing and harvests should be used? The option “lucerne ley fixed sow harvest at flowering” in the management toolbox only allows for one harvest in one simulation, but actually we had 3-4 harvests every year. I’m wondering which module/option/method do you use for input multiple harvest times in APSIM model?

Kind regards

[peter-devoil]

Hi (from a non-expert)

That component should harvest (at flowering) several times for up to 3 years

If your simulation isn't harvesting, perhaps the met data is so cold it isn't reaching flowering?

[Submarine-666]

Thx for your reply. The module "lucerne ley fixed sow harvest at flowering" only allows users to set harvest time for one once, i.e., there's only one harvest date. However, we actually had severals harvests during the simulation, and unfortunately none of them matched the date we set in UI. I have no idea how to set/input several harves times, and then let them "really happen" in the simulation.

[peter-devoil]

That manager module uses a dynamic rule that harvests the crop when the plant reaches flowering stage. If the lucerne module doesnt simulate flowering at the time of your experiment (very likely), it wont harvest at the same time. But... Harvesting is different from the "date lucerne is to be removed" parameter which kills/ends the crop. Harvesting the crop removes some biomass, rewinds phenology back to a leaf appearance stage, and continues to grow until theplant flowers again. Killing/ending the crop is done to advance into the next crop phase of your farming system.

The script tabs (to the right of the Properties label at the top) can show you the logic implemented by the manager component. The start_of_day tab shows some if/then/else logic that sows the crop on a specific day. The "[]" bits are substituted from the properties tab. Same for the end_of_day tab which has two tests - for harvesting, and ending the crop.

For more info, there's a half written guide to writing manager scripts that should get finished one day.

There is an simpler approach to dynamic rules that you can take: Use an operations schedule to implement your experiment from the journal.

[peter-devoil]

PS the lucerne module gets in a twist if you dont harvest at flowering. If it starts to set "grain", the windback mechanism breaks, and it thinks it's an annual cereal.

[Submarine-666]

Many thanks to your reply and that helps a lot.