Studies in plant nutrition; the effect of some organic supplements on the growth of lettuce in sand culture

The effect on growth and development of lettuce (May King Improved) resulting from the addition of organic supplements to a full inorganic culture solution has been investigated by means of sand cultures.
The addition of an aqueous extract of leaf mould resulted in enhanced growth on both a fresh and dry-weight basis. Shoot and particularly leaf growth were most markedly stimulated so that a higher shoot/root ratio was obtained. The plants receiving leaf-mould extract were also characterized by a slightly higher moisture content.
The addition of either yeast extract or hydrolysed casein did not result in any significant difference in growth as compared with plants receiving only inorganic nutrients.
The results are briefly discussed against the background of a review of the present status of our knowledge of the role of organic materials in the nutrition of higher green plants.