Connect litter pools to soil pools

[jacobcook1995]

Description

This pull request connects the litter pools to the soil pools, so that when litter decays a fraction of it enters the soil. I've also added to the example data so that the litter model can be run as part of vr_run.

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[alexdewar]

I've given this a quick once-over and it seems sensible to me. I'm a little lost on the science here though, so I'm not really able to give a more in-depth review.

[jacobcook1995]

Ahh cheers @alexdewar, I've been adding you and Diego to fairly sciencey pull requests mainly because I want to check that bad code style isn't creeping in, so a once over to check that there isn't anything glaringly bad is very helpful!

[codecov-commenter]

Codecov Report

Merging #281 (2694c07) into develop (7c97493) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop     #281   +/-   ##
========================================
  Coverage    94.25%   94.26%           
========================================
  Files           47       47           
  Lines         1915     1917    +2     
========================================
+ Hits          1805     1807    +2     
  Misses         110      110           

Files Changed	Coverage Δ
virtual_rainforest/models/litter/litter_model.py	100.00% <ø> (ø)
virtual_rainforest/models/soil/carbon.py	100.00% <ø> (ø)
virtual_rainforest/models/soil/constants.py	100.00% <ø> (ø)
virtual_rainforest/models/soil/soil_model.py	100.00% <ø> (ø)
virtual_rainforest/models/litter/constants.py	100.00% <100.00%> (ø)
virtual_rainforest/models/litter/litter_pools.py	100.00% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[vgro]

LGTM! I'm also not very familiar with the soil carbon science, but the general approach looks sensible :-)