11 March 2021

Daisy 6.09 released on all platforms

Changes since 5.88

Changed default value for snow fraction

Now precipitation is considered 100 % snow below 0 °C air temperature, instead of -2 °C, in accordance with standard practice for NMI and DMI.

Calculation of extraterrestrial radiation updated

It should now handle small timesteps better. Still based on FAO56, equation 28. Might cause minor changes to ET0.

Log to 'NUL' to discard output (also on UNIX)

New 'default_h' SoilWater parameter

Is used for initialization if no other value is specified. The value will represent soil surface, and then increase with 1 cm per cm

New 'test-cp.dai' and 'test-scn.dai' sample files

Together, these files demonstrate how to create a hotstart file, and run multiple scenarios based on that.

Optional Michaelis-Menten kinetics for biological degradation

Through the new 'decompose_SMB_pool', 'decompose_SMB_KM' and 'SMB_ref' chemical parameters.

If C is the carbon content in the specified SMB pool, and KM is the value of the 'decompose_SMB_KM' parameter, a SMB effect f_SMB on turnover is calculated as

f_SMB (C) = C / (C + KM)

If decompose_SMB_pool is negative, all SMB pools contribute to C.

Note that (decompose_SMB_pool 0) refers to SMB1, and (decompose_SMB_pool 1) to SMB2.

New 'T_ref' and 'SMB_ref' chemical parameters.

These scale the temperature effect (f_T) on turnover and the SMB effect (f_SMB) on turnover to the specified temperature ('T_ref') or SMB carbon content ('SMB_ref').

T_scale = 1.0 / f_T (T_ref)
SMB_scale = 1.0 / f_SMB (SMB_ref)

The scaled temperature effect (f_Ts) is then

f_Ts (T) = T_scale * f_T (T)

similarly, the scaled SMB effect (f_SMBs) is

f_SMBs (C) = SMB_scale * f_SMB (C)

and it follows that

f_Ts (T_ref) = f_SMBs (SMB_ref) = 1.0

New '-L' switch: supress daisy.log

New 'M_vGBS', 'hypweb', and 'M_BivG' hydraulic models

Note: The 'M_vGBS' and 'hypweb' are not enabled on MacOS yet.

The Millet and Maize parameterization had a too high specific_LAI

Reorganization of chemicals

'base' is new base class for chemicals.
'FOCUS' model decompose mostly follows FOCUS recommendations.
'default' model still exists, and use traditional PLF for abiotic factors.
'nutrient' base class for C and N.
'C' base classes for carbon.
'DOC' parameterization for dissolved organic carbon.
'N' base class for nitrogen
'MIN' base class for mineral nitrogen
'NO3' and 'NH4' as before.
'DON' parameterization for dissolved organic nitrogen.

The base classes are useful for logging:

("Soil chemical" (chemical MIN))

will log all mineral nitrogen in the soil.

The parameterizations in chemistry-base.dai and chemistry.dai has been updated, if you have defined your own pesticides they might need to be updated.

DON/DOC are generated by the experimental 'mulch' module, and not fully supported yet.

New NNI_crit and NNI_pot crop partitioning parameters

These let N status affect partitioning between leaves and stem. Described in the article below.

Added "Winter Wheat JG" parameterization

Described here:

Gyldengren, J. G., Abrahamsen, P., Olesen, J. E., Styczen, M., Hansen, S., & Gislum, R. (2020). Effects of winter wheat N status on assimilate and N partitioning in the mechanistic agroecosystem model DAISY. Journal of Agronomy and Crop Science.

This partitioning is based on new field experiments and knowledge, and utilizes the NNI partitioning described above, the NO3_uptake parameter described further down, as well as the 'Seed' model for initial growth. This also means that the amount of seed needs to be specified when sowing.

(sow "Winter Wheat JG" (seed 180 [kg w.w./ha]))

New 'root_homogeneity' horizon parameter

The value is multiplied to the effective root density for this horizon, affecting water and nitrogen uptake. Is will not affect the
root mass, or rhizodeposition. Set it to a value smaller than 1 to emulate the effect of soil compaction.

New 'top' heatrect model

This force the entire soil profile to have the temperature of the upper boundary, usually the air temperature. Useful for a column experiment where the column is not isolated.

It only works with 2D setups. Use "(Movement rectangle (heat top) ...)" to activate.

New 'litter_washoff_coefficient' chemical parameter

Control washoff from litter layer, analogue to 'canopy_washoff_coefficient'. Default value is 1, corresponding to
chemical being fully dissolved in the water. This should give identical results as in version 5.90 and before.

Made 'with-column' useful for soil tests

(with-column Andeby
  (wait (soil_water_pressure_above (height -10 [cm]) (potential -50 [cm]))))

works now, didn't before.

You can now stop simulation after specified time

(stop_when (walltime (seconds 5)))

You can also specify other time units, e.g.

(stop_when (walltime (hours 2) (minutes 10) (seconds 1) (microseconds 16)))

It can be combined with the simulation time based stop condition

(stop 1988 4 1 1)
(stop_when (walltime (seconds 10)))

the simulation will stop when one of the two conditions are fullfiled.