Effects of adding humidity and straw to manure for reducing weed seed viability

In order to investigate viability rate of weed seeds in process of dairy cow manure composting, a completely block randomized design with four replications was conducted at Veterinary Research Institute of Tehran University and Weed Seeds Departmentof Iranian Research Institute of plant protection in 2010. Factors included humidity at 2 levels (with and without), adding straw (hydrocarbonic material) at 4 levels (0%, 1%, 2% and 4%) and sampling time of weed seeds at 5 levels (0, 15, 30, 45 and 60 days). The experiment carried out on 13 weed seeds species and percent of viability was measured. Among 13 species of weed seeds, 10 species were total decay. Adding the straw, and sampling time had significantly effects on percent of viability in field bindweed, dodder and yellow sweet clover but adding humidity had only significantly effect on percent of viability of field bindweed. Interaction effect of adding straw and sampling time were significant at three species weeds, soadding 1% straw in 15th day reduced percent of viability. Adding humidity had less effect on percent of viability among these three factors.