Effects of Stockpiled and Composted Manures on Germination and Initial Growth of Cress (Lepidium sativum)

Seed germination inhibition and plant injuries have been reported following the application of fresh or partially composted livestock wastes to soils. Water extracts from different kinds of composted manures and from stockpiled dairy manure were compared with soil solution and distilled water for their effects on germination, initial plant growth and root development of cress (Lepidium sativum L.). Water extracts from composted and stockpiled dairy manures decreased the rate of germination compared to biomature composted manures. After 120 h of incubation, the number of normal seedlings and the growth of cress radicles were lower when exposed to composted or stockpiled dairy manures than to reference biomature composted manure water extracts, indicating that the dairy manure composted outdoors during autumn and winter was not fully biomature. Other tests such as the optical density (E4/E6) and the amounts of lipids extracted by diethyl ether and by chloroform from manures confirmed the immaturity of composted dairy manure.