nutrients = [
  { formula: "NNO3", name: "Nitrate" },
  { formula: "NNH4", name: "Ammonium" },
  { formula: "P",    name: "Phosphorus" },
  { formula: "K",    name: "Potassium" },
  { formula: "Ca",   name: "Calcium" },
  { formula: "Mg",   name: "Magnesium" },
  { formula: "S",    name: "Sulfur" },
  { formula: "Na",   name: "Sodium" },
  { formula: "Cl",   name: "Chloride" },
  { formula: "Si",   name: "Silicon" },
  { formula: "Fe",   name: "Iron" },
  { formula: "Zn",   name: "Zinc" },
  { formula: "B",    name: "Boron" },
  { formula: "Mn",   name: "Manganese" },
  { formula: "Cu",   name: "Copper" },
  { formula: "Mo",   name: "Molybdenum" }
]

nutrients.each do |attrs|
  Nutrient.find_or_create_by!(attrs)
end