Ground natural phosphate materials — including milled calcium phosphates, aluminum calcium phosphates, and phosphatic chalk — represent a more processed stage of phosphate ore, with particle size reduction making them more directly usable as direct-application fertilizers or as intermediate inputs for superphosphate and triple superphosphate production. The degree of grinding and P₂O₅ content are the primary commercial specifications that determine value and end-use suitability. Importers should distinguish this heading from chemically processed phosphate fertilizers, which are classified elsewhere in the fertilizer schedule. As with unground phosphate, this heading is designated for import reporting purposes in the US schedule.

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