title: Nutrient loads of small-scale swine manure composting to groundwater and its prevention by covering: a case study.
abstract: Small-scale composting is applied to recycle manure and biomass around the globe. Piles frequently site outside near field where bio-waste comes or compost goes within developing rural regions. However, little equipment or policy besides cover of common materials addressed concerns about its exposure to rainfall and subsequent leachate towards groundwater. In addition, little is known about its nutrient load to groundwater and covers' effect on nutrient unloading. Differently covered swine manure piles were composted outdoors with exposure to rain, then columns consisted of resultant compost of varying maturing age and soil were leached by simulated rainfall. Leachate TN, NH4 (+)-N, NO3 (-)-N, TP, and DP were modeled by regression analysis, and further, integral of quadratic curve or nutrient load index (NLI) was designated as proxy for nutrient load. Log response ratio was employed to qualify covers' effect on nutrient unloading. This case raised higher concern about leachate NH4 (+)-N than NO3 (-)-N for former's lower category in groundwater quality standard. The integrated NLIs or general nutrient load for six intervals, averagely divided from composting day of 60-120, decreased by 31, 37, 45, 56, and 73 % consecutively. Covers could unload nutrient to underground and function better to prevent P than N from leaching. Capabilities of piles covered by rice straw (CR) and soil (CS) to unload respectively are 77 and 72 % of by film (CF).
authors.affiliation: Resources and Environment College, Southwest University, No.1 Tiansheng Road, Chongqing, 400716, China.|Three Gorges Reservoir Area Key Laboratory of the Ministry of Education, No.2 Tiansheng Road, Chongqing, 400716, China.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Resources and Environment College, Southwest University, No.1 Tiansheng Road, Chongqing, 400716, China.|Three Gorges Reservoir Area Key Laboratory of the Ministry of Education, No.2 Tiansheng Road, Chongqing, 400716, China.
authors.forename: Junjing
authors.initials: J
authors.lastname: Qiao
authors.affiliation: Resources and Environment College, Southwest University, No.1 Tiansheng Road, Chongqing, 400716, China. swuboxfore@sina.cn.|Three Gorges Reservoir Area Key Laboratory of the Ministry of Education, No.2 Tiansheng Road, Chongqing, 400716, China. swuboxfore@sina.cn.
authors.forename: Yucheng
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Resources and Environment College, Southwest University, No.1 Tiansheng Road, Chongqing, 400716, China.|Three Gorges Reservoir Area Key Laboratory of the Ministry of Education, No.2 Tiansheng Road, Chongqing, 400716, China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000818:Animals; D060587:Groundwater / Q000032:analysis*; D008372:Manure / Q000032:analysis; D012275:Oryza / Q000737:chemistry; D035261:Plant Components, Aerial / Q000737:chemistry; D011891:Rain; D012987:Soil / Q000737:chemistry*; D013552:Swine; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008372:Manure; D012987:Soil; D014874:Water Pollutants, Chemical
keywords: Compost leachate; Composting cover; Groundwater; Nutrient load effect quantification; Swine manure