Units

Units

Consistent units are what make the small-scale question answerable across crops. This page fixes the conventions; use them everywhere — narrative, structured data, and experiment records.

Base units

Quantity	Unit	Notes
Length / spacing	cm (centimeters)	state width × depth for planting; intra-row × inter-row for density
Area	m² (square meters)	ha (hectares) for large scale; 1 ha = 10,000 m²
Mass	g (grams), kg (kilograms)	seed/plant: g; plot or bag quantity: kg
Yield	kg/m² and kg/ha	see conversion rules below
Temperature	°C	min_c / max_c / optimal_c
Water	mm or L/m²	1 mm rain = 1 L/m². State as seasonal total + peak weekly
Seeding rate	kg/ha and g/m²
Density	plants/m²
Moisture	% (weight basis)	seed moisture content, % fresh weight

Yield scales (PRD §12)

Yield should be expressed at multiple scales where possible:

g / plant
g / m²
kg / 10 m²
kg / 100 m²
kg / 1,000 m²
kg / hectare

Choose the scale that matches the claim and is least misleading; always give the area the number refers to.

Conversions (memorize these)

• Area: 1 ha = 10,000 m² · 1,000 m² = 0.1 ha · 100 m² = 1 a (are-ish, but we just say 100 m²).
• Yield per area:
  • 1 g/m² = 10 kg/ha (and 1 kg/ha = 0.1 g/m²).
  • Example: 1,200 kg/ha = 120 g/m² = 0.12 kg/m².
  • Per plot scale: 120 g/m² × 10 m² = 1.2 kg / 10 m²; × 100 = 12 kg / 100 m².
• Water: 1 mm rainfall = 1 L/m² — a 300 mm season on 100 m² = 30,000 L = 30 m³.
• Density: seeding rate (kg/ha) to plants/ha depends on 1,000-seed weight and germination; note the thousand-seed weight (g) whenever translating.
• Moisture conversions: storage-safe thresholds are more meaningful than raw numbers; always state basis (wet basis if not specified).

Structured data conventions

In data/crops/*.yaml:

• Temperatures: optimal_min_c, optimal_max_c, germination_min_c, frost_tolerant.
• Spacing: spacing_cm.min/.max, row_spacing_cm.min/.max.
• Yield: typical_g_m2.min/.max plus optional kg_ha range with provenance.
• Values without evidence: null or unknown — never invent.

Reporting practical quantities

For the human-scale question, report the quantities a practitioner actually handles:

• Area of a “small plot” (a garden bed, a 20 m² bed)
• Weight of harvestable product (g/kg)
• Labor time (h per kg, h per m²) — separate from yield
• Equipment needed (hand tools, containers)

Rounding and significant figures

• Field-scale agronomy: round to 1 significant figure in %/kg/ha advice where evidence is Moderate or less (e.g., “≈120 g/m²”, not “121.3 g/m²”).
• Original experiments: keep raw measurements unrounded in the record; round only in interpretation.

Not-your-problem units

• Do not silently convert U.S. customary without showing the metric value (state both, metric first). Example: “≈45 cm (≈18 in)”.
• Do not embed locale assumptions (e.g., USDA climate zones) without translations. Prefer explicit temperature ranges.