Comparison of liquid manure spreading practices on tile drain water quality - Final report

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Foran, Mary Ellen
Blackie, Murray

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Ontario Ministry of the Environment

Abstract

Five liquid manure spreading events have been monitored and compared for their relative bacterial and nutrient loading to the tile drain water on a Perth clay loam soil under conventional tillage. Two events involved the comparison of irrigated swine manure on cropland that had been recently tilled and on cropland that had not been tilled prior to the manure applications. The spreading events took place in May and November 1991. Two events involved the comparison of the irrigation and the injection methods of manure application. These spreading events took place in June and October 1991. The final spreading event involved the comparison of loading from a field tile drain with blocked flow for six days versus a field tile drain with unblocked flow at the time of the application. This spreading event took place in May 1992. Observation chambers and shallow sampling wells were installed in the study area in order to monitor changes in the tile drain water and groundwater quality, respectively. Bacterial parameters tested for in the manure, tile drains, groundwater and soil included fecal coliform, fecal streptococcus, Escherichia coli and the biotracer, nalidixic acid resistant Escherichia coli (EC(NA)). The EC(NA) were introduced with the liquid manure to trace bacterial movement in the soil and water. The chemical parameters tested for in the tile drain water included; biochemical oxygen demand, suspended solids, free ammonia, total kjeldahl nitrogen, nitrate, nitrite, total phosphorus, dissolved reactive phosphorus, pH, chloride, conductivity, and potassium. The chemical parameters tested for in the groundwater included; dissolved organic carbon, ammonia, nitrate, dissolved reactive phosphorus, pH, chloride, conductivity and potassium. Tilling of the land prior to manure application appeared to have decreased the amount of bacteria and nutrient loading to the tile drain water. In May 1991 the unfilled trial was one order of magnitude higher in the calculated bacterial and nutrient loading to the tile drains compared to the tilled trial. At the time of the November spreading event, tile drains were not flowing and no loading to the tile drains was observed. EC(NA) were found at depth in the soil profile for both the tilled and the untilled trials. However, at the 75 cm depth they were present in significantly higher concentrations on the untilled trial compared to the tilled trial. No EC(NA) contamination in the wells was observed in this event. Injecting manure on cropland appeared to have increased the amount of bacterial and nutrient loading to the tile drain water compared to the irrigation method of application. In June 1991 the injection method of application resulted in the bacterial loading to the tile drains being two orders of magnitude higher and the nutrient loading being one order of magnitude higher compared to the irrigation method. Groundwater contamination was found to occur within 5 hours on both the injected (well depth 3.3 m) and the irrigated (well depth 4.1 m) trial. At the time of the October spreading event, tile drains were not flowing and no loading to the tile drains was observed. EC(NA) were found at depth in the soil profile for both the injected and the irrigated trials. However, at the 75 cm depth they were found in significantly higher concentrations on the injected trial compared to the irrigated trial. No EC(NA) contamination was found in the wells. High fecal streptococcus counts were found in the well on the irrigated trial within two days of the manure application and remained high for 12 days. The wells on the irrigated trial were dry at this time. No conclusions regarding the effect of blocking tile drain flow can be made from the May 1992 spreading event. Neither trial resulted in bacterial or nutrient contamination of the tile drain water even though tile drains were flowing. The sampling wells showed no signs of contamination. No soil data was available as no soil samples for bacterial analysis were taken. The 15 mm rain that fell the day prior to the spreading event may have reduced the preferential transport of the manure components. In late November 1991 nitrate and chloride levels increased in all the samples taken from the tile drains and sampling wells compared to the samples taken earlier in the year. The increase can not be attributed solely to the manure applications as fertilizer application and crop residue breakdown may also be contributing factors.

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Ontario Ministry of the Environment
Waste Management Reports

Keywords

manure application, liquid manure, tile drain, water quality, groundwater contamination, bacteria, nutrient loading, conventional tillage, fecal coliform, fecal streptococcus, Escherichia coli, biotracer, nalidixic acid resistant Escherichia coli, cropland

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