As early as 1864 Wolff brought out the need for a systematic tabulation of plant ash analyses and in his book published the best data available at that time. He reported CaO, MgO, K20, Na2O, Fe2O3 , PO3 , SO3 , SiO2 and Cl. But he gave neither the number of analyses nor the source of the samples. Similar data are given by both Leach and Sherman.
Proceedings of the Iowa Academy of Science
©1931 Iowa Academy of Science, Inc.
Wendt, Louise and Wilkinson, John A.
"Quantitative Analysis of Lettuce Ash,"
Proceedings of the Iowa Academy of Science, 38(1), 159-161.
Available at: https://scholarworks.uni.edu/pias/vol38/iss1/18