The Effect of Manure Application Method on Nutrient and Microbial Runoff Transport and Soil Biological Health Indicators

Two projects were completed to provide significant new information to the agricultural industry regarding the environmental implications and soil health impacts related to land application of swine manure. The first study reports on the runoff transport of nutrients and microbials as affected by manure application method and time following application. The second study provides information about the effect of application method and time following application on soil health indicators using arthropod abundance and diversity as a biological indicator. The information gained through these studies will provide beneficial information to the pork industry on the impact of manure application method and the timing of application on limiting the movement of manure constituents with runoff while improving soil biological health. The first field study was conducted to measure the effects of manure application method and time following application on runoff transport of nutrients and microbials. Swine slurry was applied to the soil by a commercial applicator in June 2014 using broadcast and injection methods. Simulated rainfall events were applied to the study plots following manure application in June, July, and August 2014. The broadcast treatment resulted in significantly greater dissolved and total phosphorous runoff loads than the injection treatment. Soil erosion was greater for the injection plots than for the broadcast treatment sites. Overland flow rate variation had a significant impact on all measured water quality parameters. Significant reductions in nutrient transport loads were observed on plots where slurry was injected rather than broadcast. Nutrient and microbial transport loads decreased significantly during the 45 days following slurry application for both treatments. The second study was conducted to determine the impact of manure application method and time following application on soil health by examining the chemical and biological responses to the treatments over time. Swine slurry for this study was also applied to field plots in June 2014 by a commercial applicator using broadcast and injection methods. The broadcast treatment resulted in a significant increase in hypogastruridae and isotomidae populations over time. For the broadcast treatment, significant initial increases in nutrient content were observed, while the injection treatment showed very little initial response with much greater increases later in the study. Time following slurry application had a significant impact on all measured soil characteristics and all but one of the arthropod Orders that were quantified. Application method had a significant impact on all measured soil chemical characteristics, but was only significant for the hypogastruridae, isotomidae, and pseudoscorpion populations. Advisor: Amy M. Schmid