Complex sentence: Traditional potash sources included applying ash to the land and ploughing in crop residues after the harvest, and artificial potash fertilisers were not used until deposits of potash salts were discovered in Germany in 1861.
Split into simpler sentences: Traditional potash sources included applying ash to the land and ploughing in crop residues after the harvest. Artificial potash fertilisers were not used until deposits of potash salts were discovered in Germany in 1861.