Agronomic Management Scenarios

This is a pre-alpha DRAFT. Changes discussed in PR review should be specified as new issues / discussions.

Purpose

The purpose of this directory is to provide a set of tools that will allow users to specify agronomic management scenarios, optionally with probabilistic inputs that represent uncertainty in historical agronomic practices and/or variability in future scenarios.

General Overview

• Events are specified in one or more scenarios.yaml files.
• The events.R script reads scenarios.yaml and generates JSON files that follow the PEcAn events schema.
• These JSON files can then be used by PEcAn functions to convert them into model-specific formats. For example, PEcAn.SIPNET::write.configs.SIPNET function will read these in and generate SIPNET events.in files.

Scenario Configuration File

The configuration file scenarios.yaml includes the following elements:

• site_id, start_year, and end_year: unique site identifier and range of years to be simulated.
• pecan_events_version: optional schema version (defaults to 0.1.0).
• baseline.events: the baseline event definitions.
• scenarios: per-scenario overrides (only include changes).
• name (optional but recommended): unique identifier for matching overrides to baseline events of the same event_type.

Event definitions use field names from PEcAn events schema where possible, with the following exceptions for end-user convenience:

• Dates are MM-DD strings that get expanded to YYYY-MM-DD for each year. TODO: Make sure this supports YYYY-MM-DD format so events can vary each year.
• Irrigation schedules can be specified as a list under date or as date: {start, every_days, n_events}.

Example:

site_id: herb_site_1
start_year: 2016
end_year: 2024

baseline:
  events:
    - event_type: tillage
      name: tillage_spring
      date: "03-20"
      tillage_eff_0to1: 0.35
    - event_type: fertilization
      name: fertilization_spring
      date: "03-25"
      nh4_n_kg_m2: 0.02
    - event_type: planting
      name: planting_spring
      date: "04-10"
      leaf_c_kg_m2: 0.0034
    - event_type: irrigation
      name: irrigation_growing
      date: ["05-15", "06-15", "07-15", "08-15", "09-01", "09-15"]
      amount_mm: 90
      method: canopy
    - event_type: harvest
      name: harvest_fall
      date: "10-10"
      frac_above_removed_0to1: 0.5
      frac_below_removed_0to1: 0.0

scenarios:
  baseline: {}
  reduced_till:
    events:
      - event_type: tillage
        name: tillage_spring
        tillage_eff_0to1: 0.10

MVP Demonstration

For initial MVP, these files are intended to be reused across all sites to represent management scenarios for herbaceous systems. Future work will:

• Review and revise architecture both for this draft and iteratively.
• Produce site-specific management events for both inventories and projections.
• Generate ensembles representing uncertainty and / or scenario based variance.

Overview

The agronomic management events described below broadly reflect common practices in CA for annual row crops, based on UC ANR and CDFA-FREP guidance.

Scenario	Changes from baseline
baseline	Following conventional practices
compost	Adds compost (0.25 kg C/m2, 0.015 kg N/m2); remove mineral N fertilizer
reduced_till	Reduce tillage intensity to 0.10.
zero_till	No tillage with tillage_eff_0to1 = 0.00.
reduced_irrig_drip	Replace canopy irrigation schedule with 40 drip events (8 mm each, soil method).
stacked	Combine compost, reduced_till, and reduced_irrig treatments.

Details

• baseline

  • Compost: none
  • Tillage: conventional, tillage_eff_0to1 = 0.35
  • Mineral N: 0.020 kg N/m2 per year (200 kg N/ha), pre-plant
  • Irrigation: 6 sprinkler/overhead events (method = "canopy"), 90 mm each, May–September (seasonal total = 540 mm)

• compost

  • Compost: 0.25 kg C/m2 and 0.015 kg N/m2 each year (late February): ~10 tons/acre compost at ~35% C and C:N = 16
  • Mineral N: 0 (orgN replaces mineral N)

• reduced_till

  • Tillage: reduced intensity, tillage_eff_0to1 = 0.10

• zero_till

  • Tillage: no tillage, tillage_eff_0to1 = 0.00

• reduced_irrig_drip

  • Irrigation: drip: 40 applications of 8 mm (~3x/week from May through late August, seasonal total ~320 mm)

• stacked

  • Compost: 0.25 kg C/m2 and 0.015 kg N/m2 per year
  • Tillage: reduced intensity, tillage_eff_0to1 = 0.10
  • Irrigation: as reduced_irrig_drip (40 x 8 mm, soil)

Regenerating Outputs

Produces scenario outputs generated by events.R each file contains a single PEcAn events timeline:

• data/events_baseline.json
• data/events_compost.json
• data/events_reduced_till.json
• data/events_zero_till.json
• data/events_reduced_irrig_drip.json
• data/events_stacked.json

Timing of Events

Annually (2016–2024):

• Compost: Feb 20
• Tillage: Mar 20
• Mineral N: Mar 25
• Planting: Apr 10
• Irrigation:
  • baseline / compost / reduced_till / zero_till:
    • May 15, Jun 15, Jul 15, Aug 15, Sep 1, Sep 15
    • 90 mm each, method = "canopy"
  • reduced_irrig_drip / stacked:
    • 40 events, 8 mm every 3 days starting May 1
• Harvest: Oct 10

All events use site_id = "herb_site_1" and are sorted by date.

References

OM Application

• CDFA Compost Application Rate White Paper

Fertilization

• USDA Nutrient Management in Organic Systems Western States Implementation Guide
• UCANR Fertilization Guidelines

Irrigation

• UCANR Irrigation of Processing Tomatoes
• Inouye "Crop Water Requirements Imperial Valley"