two patentable extracts from leonardite have shown positive yield and hormone like responses on a number of controlled environment and field grown crops. in 1985, replicated field trials on processing tomatoes produced average yield increases of 10. 5 over untreated controls. trials on cotton during the same year evaluating the use of these materials with and without other growth controlling chemicals produced an average yield increase of 11. 2 unreplicated large field trials on vineyards of differing varieties produced a range of responses in total yield from 3 to 70 with an average increase of 25. in these studies the extract that contains the greatest amount of the humic substances is used as an early season soil treatment, while the other is used as a post emergence foliar spray. based on observations of these and other studies it appears that the extracts, when used singly or in tandem, trigger a flowering response in many species of plants. (edited author abstract) 8 refs