The fertilizer industry developed alongside agriculture. As the role of different nutrients (not limited to NPK) was recognized, application of single nutrient fertilizers became impractical, and farmers needed compound fertilizers. Small-scale regional fertilizer mixers were becoming uncompetitive with large-scale bulk producers, resulting in ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.