Animal Waste

Intensive livestock and poultry production results in large volumes of waste that threaten surface- and groundwater quality in the event of waste spills, leakage from waste storage facilities and runoff from fields on which an excessive amount of waste has been applied as fertilizer. Animal waste generally refers to manure but also includes wastewater, urine, bedding, poultry litter and animal carcasses. The most common waste management practices include techniques to (1) limit waste runoff, such as cementing and curbing animal confinement areas or planting grassed buffers around these areas (2) collect and store waste, such as scraping or flushing systems and storage tanks or retention ponds (3) alter or treat waste, such as reformulating feed mixes or composting and (4) utilization of waste, such as organic fertilizer or additive to animal feed (US GAO, 1999).

Rice Straw

Worldwide rice production is about 600 million t per year resulting in 810 million t of rice straw production, according to Food and Agriculture Organization of the United Nations. The most common treatments of rice straw include mulching in rice fields, on-site burning for producing manure or composting. Burning, which is difficult in most existing combustion systems, affects the quality and the environment mainly due to CO2 emission (PUtun et al., 2004). Composting is an attractive treatment of rice straw enhancing plant growth and may be suitable for agricultural applications; however rice straw is rich in C and poor in N and its C/N can vary from 50 to 150 limiting the composting process (Campbell et al., 1995).

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