Mowing and grazing

Biomass losses due to management $M_{ts}$ [kg ha⁻¹] are caused by mowing $MO{W}_{ts}$ [kg ha⁻¹] and grazing $GR{Z}_{ts}$ [kg ha⁻¹]:

$$M_{ts}=MO{W}_{ts}+GR{Z}_{ts}$$

Mowing

The mown biomass $MO{W}_{ts}$ [kg ha⁻¹] is decribed by:

$$MO{W}_{ts}=\frac{max(H_{ts}-CU{T}_t,0)}{H_{ts}}\cdot B_{A,ts}$$

none

API

GrasslandTraitSim.mowing! Function

mowing!(
;
    container,
    mowing_height,
    above_biomass,
    actual_height
)

Simulate the mown biomass of each plant species.

source

Grazing

The grazed biomass $GR{Z}_{ts}$ [kg ha⁻¹] is defined as:

$$\begin{array}{rl}GR{Z}_{ts}& =\frac{{\kappa }_{GRZ}\cdot L{D}_t\cdot (B_{F,t}{)}^2}{({\kappa }_{GRZ}\cdot L{D}_t\cdot {\eta }_{GRZ}{)}^2+(B_{F,t}{)}^2}\cdot \frac{LN{C}_{GRZ,ts}\cdot H_{GRZ,ts}\cdot B_{F,ts}}{\sum _{i=1}^{S}LN{C}_{GRZ,ti}\cdot H_{GRZ,ti}\cdot B_{F,ti}}\\ B_{F,ts}& =max(1-\frac{{\eta }_{GRZ,H}}{H_{ts}},0)\cdot B_{A,ts}\\ B_{F,t}& =\sum _{s=1}^S{B}_{F,ts}\\ LN{C}_{GRZ,ts}& ={\left(\frac{ln{c}_s}{LN{C}_{cwm,t}}\right)}^{{\beta }_{GRZ,lnc}}\\ LN{C}_{cwm,t}& =\sum _{s=1}^S\frac{B_{F,ts}}{B_{F,t}}\cdot ln{c}_s\\ H_{GRZ,ts}& ={\left(\frac{H_{ts}}{H_{cwm,t}}\right)}^{{\beta }_{GRZ,H}}\\ H_{cwm,t}& =\sum _{s=1}^S\frac{B_{F,ts}}{B_{F,t}}\cdot H_{ts}\end{array}$$

The equation is partly based on Moulin et al. (2021).

• ${\kappa }_{GRZ}$ maximum consumption of biomass per livestock and day [kg ha⁻¹]

• ${\eta }_{GRZ}$ controls when the farmer starts to supply additional fooder [-]

• ${\eta }_{GRZ,H}$ plant parts below this height are not accessible to grazers. [m]

• ${\beta }_{GRZ,lnc}$ scales the influence of the leaf nitrogen content on the preference of the grazers [-]

• ${\beta }_{GRZ,H}$ scales the influence of the height on the preference of the grazers [-]

Visualization

• Graphic of the total grazed biomass (first term of the grazing equation)

Livestock Density (LD)	3
Controls when the farmer starts to supply additional fooder (η_GRZ)	2
Consumption per livestock and day (κ_GRZ)	22

API

GrasslandTraitSim.grazing! Function

grazing!(; container, LD, above_biomass, actual_height)

Simulates the removal of biomass by grazing and trampling for each species.

source