Assertion: fertilizer's trace element | /r/HasProperty | iron
Facets:
Source sentences:
text: Micronutrients, or trace elements, needed in very small amounts, are iron, manganese, zinc, copper, molybdenum, boron, silicon, and chlorine.
text: The main trace elements in fertilizers are calcium, magnesium, iron, copper, manganese, zinc, molybdenum, boron, and sulfur (you can usually purchase these items individually as well).