Saini R, Halverson L J, Lorimor J C
Department of Agronomy, 2537 Agronomy Hall, Iowa State University, Ames, IA 50011-1010, USA.
J Environ Qual. 2003 Sep-Oct;32(5):1865-72. doi: 10.2134/jeq2003.1865.
The time between swine (Sus scrofa) manure application to soil as a crop fertilizer, the first rainfall event, and the frequency of rainfall events should influence leaching potential of fecal pathogens. Soil microcosms were inoculated in the lab with a swine manure isolate of Escherichia coli, strain RS2G, expressing green fluorescent protein, to examine how timing and frequency of rainfall events influences RS2G leaching and survival in soil. Liquid swine manure inoculated with RS2G was applied to intact soil cores (20 cm in diameter x 30 cm long) 4, 8, or 16 d before the first rainfall event (50.8 mm over a 4-h period), and each core received one to three rainfall events. Manure application methods (no-till surface-broadcast, broadcast and incorporated, and tilled before broadcast) had no affect on leaching, although there was greater survival in soils when the manure had been incorporated. Most of the RS2G in the leachate appeared following the first rainfall event and RS2G leaching decreased with increasing time between manure application and the first rainfall, although leachates contained as much as 3.4 to 4.5 log colony forming units (CFU) 100 mL(-1) of RS2G when the first rainfall occurred 16 d after manure application. With increasing frequency of rainfalls there was a decrease in subsequent concentrations of RS2G in the leachate. There was no correlation between leachate RS2G and total coliforms or fecal streptococci concentrations. Soil RS2G numbers were 1 to 10% of the inoculum regardless of the length of time between manure application and the first rainfall. RS2G leaching was mostly influenced by the time between manure application and first rainfall event, and significant leaching and survival in soil was possible even if the first rain occurred 16 d after manure application.
将猪（野猪）粪便作为作物肥料施用到土壤后，首次降雨事件以及降雨事件的频率应会影响粪便病原体的淋溶潜力。在实验室中，用表达绿色荧光蛋白的猪粪便分离大肠杆菌RS2G菌株对土壤微观模型进行接种，以研究降雨事件的时间和频率如何影响RS2G在土壤中的淋溶和存活。在首次降雨事件（4小时内降雨量为50.8毫米）前4、8或16天，将接种了RS2G的液态猪粪施用到完整的土柱（直径20厘米×长30厘米）上，每个土柱接受一到三次降雨事件。尽管将粪便混入土壤时土壤中的存活率更高，但施肥方法（免耕表面撒播、撒播并混入、撒播前翻耕）对淋溶没有影响。渗滤液中的大多数RS2G在首次降雨事件后出现，并且RS2G淋溶随着施肥与首次降雨之间时间的增加而减少，不过当首次降雨在施肥后16天发生时，渗滤液中每100毫升含有多达3.4至4.5个对数菌落形成单位（CFU）的RS2G。随着降雨频率的增加，渗滤液中后续RS2G的浓度降低。渗滤液中的RS2G与总大肠菌群或粪链球菌浓度之间没有相关性。无论施肥与首次降雨之间的时间长短，土壤中的RS2G数量均为接种量的1%至10%。RS2G淋溶主要受施肥与首次降雨事件之间的时间影响，即使首次降雨在施肥后16天发生，RS2G在土壤中也可能大量淋溶和存活。
