Release of fixed ammonium from soils and rocks by ball milling

Abstract
Fixed ammonium can be released from rocks and soils by prolonged ball milling (100 hr). The release was shown by a decrease in fixed ammonium levels in milled samples compared to non‐milled soils. Secondary clay minerals were disrupted by milling. Organic nitrogen containing materials did not release significant amounts of exchangeable ammonium during 100 hr of ball milling.