Management rules and external factors - INRA Montpellier

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Management rules and external factors - INRA Montpellier

Rule n°10 : Crop planting decision rule

Title

Time step for examining the rule

Limits of time step for applying the rule

Options

To crop or not to crop

year

Year 1 to tree harvest

Y/N

State variables required for the rule Net margin of crop in alleys for last year (NM crop )

Cost of weed control in tree rows (C weed )

Net margin from cropped area with no crop (Nm nocrop )

Likely consequences known by the

manager

Increased profitability of agroforestry system, if crop rotation is ended

when the rotation becomes uneconomic.

Effect on the tree, effect on future options for growing crops (weed

control), cost of managing the uncropped alley…

State variables required for the rule

Crop yield over time, past expected yield over time, past climate

conditions (to mitigate expected-actual yield discrepancies)

Tree diameter over time, canopy width, lowest branches and machines,

recent history of pruning (intention to prune or thin the stand),

Decision criterion

Economic management rule:

IF NM crop - C weed > NM nocrop THEN Crop ELSE Not Crop

Questions and comments

This rule needs to be elaborated

In the case of dry farming, water saving fallow should be considered as a

crop, not as the end of the cropping system. Therefore, the rotation will

be imposed with a fallow period, and the decision to crop will not be

examined during fallow years. Alternately, the decision to crop could

depend on the water content of the soil at a given date. But this would

mean that the fallow water use can be modelled. We therefore need a

fallow module in the crop model.

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