An investigation on weed seed viability during composting process.
2006
Salami, Homeyra | Khalaqani, Javad | Qarah Daghi, Akbar | Rahimiyan, Hamid | Aqa Beygi, Fatemeh
Adding fresh manure to cropland result in an increased weed population from seed present in the manure. Composting process can destroy weed seed viability. In an experiment seed viability of sixteen important weed species in forage fields were investigated during composting process. Seeds enclosed within nylon mesh bags were buried into the two compost piles, at 0.5, 1 and 1.5 meters depths from surface for 4 months in the early of summer, autumn and winter in 2004. Two compost piles made from cow manure and one of them was covered by plastic sheets. Seed packets were removed monthly to test for seed viability. Moisture content of manure was around 70%. The results showed a dependence of weed seed viability loss in compost on composting temperature. Compost piles tended to have hotter temperatures at 0.5 meter (60-70°C) than 1 and 1.5 m. This is probably because the pile was better aerated at 0.5 m. Weed seeds lost their viability at the 0.5 m depth where had the most temperature in comparison to deeper depths. In the covered compost pile, seed viability loss and temperature degree were lower than uncovered compost pile. Almost all of weed species were killed after 2 months exposure at 0.5 m into the uncovered compost piles in summer. However, only viability of Cuscuta monogyna, Gold bachia laevigata, Chenopodium album and Amaranthus retroflexus were decreased after 3 months. Chemical test showed that water content reduced after one month composting. PH value were 7 to 8 and changed in that range. Carbon to nitrogen ratio was between 15- 20 after three months composting process. It was suitable range because it commended to shoud be less than twenty.
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