Understanding how Hydrogene calculates fertilizer recommendations helps you make informed decisions about your nutrient management.

The Calculation Process

Hydrogene follows a systematic approach:

1. Analyze current state (soil/water analysis)
2. Define target state (crop profile)
3. Calculate difference (nutrient gap)
4. Optimize solution (fertilizer selection)
5. Validate results (check for conflicts)

Units and Conversions

Common Units

Unit	Full Name	Used For
ppm	Parts per million	Solution concentrations
mg/L	Milligrams per liter	Same as ppm for water
meq/L	Milliequivalents per liter	Ion balance
mmol/L	Millimoles per liter	Scientific precision

Conversion Formulas

// ppm to mmol/L
mmol = ppm / atomic_weight

// Example: 200 ppm Ca to mmol
mmol_Ca = 200 / 40.08 = 4.99 mmol/L

// meq/L to ppm
ppm = meq × equivalent_weight

Nutrient Gap Analysis

The nutrient gap is calculated as:

Gap = Target - (Current Soil + Water Contribution)

Example Calculation

For Nitrogen in a tomato crop:

Source	N (ppm)
Target Profile	200
Current Soil	45
Water Contribution	5
Gap to Fill	150

Fertilizer Selection Algorithm

Hydrogene uses multi-objective optimization to:

1. Minimize cost while meeting targets
2. Balance ratios between nutrients
3. Avoid antagonisms (nutrient conflicts)
4. Respect solubility limits