stress

Composite stress factors.

A light wrapper module that bundles the water-stress factor TRANRF and the nutrient reduction factor NPKREF into a single growth reducer via the law of the minimum — the more limiting of the two factors governs growth, matching SIMPLACE Lintul5 GROWTH.

This module is deliberately minimal — the substantive computations live in WaterBalance and NutrientDemand. Use StressFactors if you want to swap in a learned alternative via the hybrid API.

StressFactors (Module)

Combine water and nutrient stress into a single growth reducer.

Source code in torchcrop/processes/stress.py

class StressFactors(nn.Module):
    """Combine water and nutrient stress into a single growth reducer."""

    def forward(
        self,
        tranrf: torch.Tensor,
        nstress: torch.Tensor,
    ) -> torch.Tensor:
        """Combine water and nutrient stress into a single growth reducer.

        Args:
            tranrf: Water-stress factor in ``[0, 1]`` from
                `WaterBalance`, shape ``[B]``.
            nstress: Nutrient reduction factor ``NPKREF`` in ``[0, 1]``
                (the ``NLUE``-transformed NPK index), shape ``[B]``.

        Returns:
            Combined stress reducer ``= min(tranrf, nstress)`` in
            ``[0, 1]``, shape ``[B]`` — the **law of the minimum**, so
            the more limiting of water/nutrient stress governs growth
            (matches SIMPLACE ``GROWTH``: ``min(TRANRF, NPKREF)``).
            This is *not* a rate — it is a multiplicative factor that
            scales the gross growth rate ``gtotal`` and therefore
            propagates into every per-organ rate
            (``g_lv``/``g_st``/``g_root``/``g_so``).
        """
        return torch.minimum(tranrf, nstress)

forward(self, tranrf, nstress)

Combine water and nutrient stress into a single growth reducer.

Parameters:

Name	Type	Description	Default
tranrf	torch.Tensor	Water-stress factor in [0, 1] from WaterBalance, shape [B].	required
nstress	torch.Tensor	Nutrient reduction factor NPKREF in [0, 1] (the NLUE-transformed NPK index), shape [B].	required

Returns:

Type	Description
Combined stress reducer ``= min(tranrf, nstress)`` in ``[0, 1]``, shape ``[B]`` — the **law of the minimum**, so the more limiting of water/nutrient stress governs growth (matches SIMPLACE ``GROWTH``	min(TRANRF, NPKREF)). This is not a rate — it is a multiplicative factor that scales the gross growth rate gtotal and therefore propagates into every per-organ rate (g_lv/g_st/g_root/g_so).

Source code in torchcrop/processes/stress.py

def forward(
    self,
    tranrf: torch.Tensor,
    nstress: torch.Tensor,
) -> torch.Tensor:
    """Combine water and nutrient stress into a single growth reducer.

    Args:
        tranrf: Water-stress factor in ``[0, 1]`` from
            `WaterBalance`, shape ``[B]``.
        nstress: Nutrient reduction factor ``NPKREF`` in ``[0, 1]``
            (the ``NLUE``-transformed NPK index), shape ``[B]``.

    Returns:
        Combined stress reducer ``= min(tranrf, nstress)`` in
        ``[0, 1]``, shape ``[B]`` — the **law of the minimum**, so
        the more limiting of water/nutrient stress governs growth
        (matches SIMPLACE ``GROWTH``: ``min(TRANRF, NPKREF)``).
        This is *not* a rate — it is a multiplicative factor that
        scales the gross growth rate ``gtotal`` and therefore
        propagates into every per-organ rate
        (``g_lv``/``g_st``/``g_root``/``g_so``).
    """
    return torch.minimum(tranrf, nstress)