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Animal manures are land applied in agronomic systems to supply essential crop nutrients and decrease dependency on chemical fertilizers. Liquid manures are traditionally surface broadcast to fields and sometimes incorporated to reduce odor and nutrient losses; however, incorporation is incompatible with no-till agriculture. Subsurface manure injection is a no-till compatible alternative application method which addresses these concerns, but likely changes the dynamics of nutrient cycling. Comparison of the two application methods has yielded mixed results and warrants further research. Therefore, the objectives of this research were to contrast the surface broadcast and subsurface injection of dairy slurry on nitrogen and carbon cycling, crop yield, and biologic responses to proxy soil health. In a forced air-flow laboratory incubation, manure injection reduced ammonia volatilization by 87% and 98% in a sandy loam and clay loam soil, respectively. The increased ammoniacal nitrogen recovery resulted in increases of soil nitrate of 13% for the sandy loam and 26% for the clay loam after 40 days of incubation. Microbial measurements were inconclusive in the laboratory. In 7 site-years of field study, soil nitrate was greater in 7 of 25 measurements under manure injection and 30% higher under injection on average during the corn pre side-dress nitrate test (PSNT) time. Soil nitrate sampling methods were assessed for fields injected with manure; a standard random sampling method had a coefficient of variation (C.V.) of 28% and was as equally repeatable as utilizing an equi-spaced distribution of cores taken across an injection band, C.V. of 30%. Both biological responses, carbon mineralization (C-min) and substrate induced respiration (SIR), were not different between application methods; both were highly variable and C-min was especially intensive logistically. Corn yield showed no consistent response to application method, but probably was not nitrogen limited. In 2 years of field study conducted on a university research farm injection resulted in greater 0-15cm soil nitrate levels than surface broadcast 1 week after application and persisted for 9 additional weeks. In injected plots, nitrate was concentrated in the injection band; nitrate movement was significant only 10cm lateral to the injection band but overall distribution fit well to a second degree polynomial, especially 2 and 4 weeks after application, R2>0.80. Evidence of leaching was observed in one year after receiving considerable rainfall in weeks 1 and 2 after application. When corn grain yield was averaged year over year, injection was 26% greater than the no- manure control, and 15% greater than surface application. Both biological metrics, C-min and microbial biomass, were stratified by depth; C-min was concentrated within the manure band leading to greater mineralization under injected applications. Microbial biomass was significantly higher under injection at the 15-30cm depth. Overall biological response to manure application method was inconclusive, however manure injection is superior to surface application in terms of nitrogen recovery. / Doctor of Philosophy / Animal manures supply nutrients essential to crop growth (notably nitrogen and phosphorous); liquid manures (pigs and dairy cattle) are commonly applied by spraying them on soils before tillage. Where no-tillage is used as a conservation measure subsurface injection can be used as an alternative to leaving manure on the soil surface. The purpose of this research was to assess nutrient cycling, crop yield, and soil health impacts of surface applied and injected dairy manure applications. Manure injection greatly reduces a nitrogen loss pathway, and as a result supplies more plant available nitrogen to the crop. Methods of soil sampling fields using injection were compared and a recommended sampling method was defined. Transport of a form of nitrogen vulnerable to movement in the ground was found to only travel 10cm away from where manure was injected. Transport of this form of nitrogen below the injection area was observed after abundant rainfall. Crop yields were sometimes higher under injection however, yields are also determined by factors other than nitrogen. Soil health was not repeatably improved under one application method, but microbial activity was greater at shallower soil depths.

published_or_final_version / Botany / Master / Master of Philosophy

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Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Fecal contamination is the pollution caused by the microorganisms residing in the intestine of warm blooded animals and humans. Bacteria are the prime cause of contamination of surface waters in the US. The transport of microorganisms into waterways can have detrimental effects on water quality and human health especially if the pathogenic strains are ingested. E. coli is used as an indicator of fecal contamination. Detection of these bacteria in a water body above set limits poses a potential health hazard. Various sources contribute to the bacterial contamination of a water body. The sources need to be identified and quantified for their E. coli content to measure bacteria loads in the waterbody accurately. In many cases, in-situ re-growth is also believed to be a considerable source of E. coli. Also re-growth of E. coli in landscapes due to favorable environmental conditions (e.g., rainfall after dry weather conditions) is one of the major phenomena affecting E. coli concentration in streams. Thus the environmental factors like temperature and soil moisture that influence transport, persistence, re-growth, and survival of E. coli in landscapes were studied. The objective of this study was to identify, characterize and quantify E. coli loads from feces of four different animals and monitor survival, growth and re-growth at four different temperatures and moisture contents over a period of seven days. Findings of this research will aid in Watershed Protection Plan (WPP) development and Total Maximum Daily Load (TMDL) development to address impairment from point and non-point source pollution of E. coli. Wildlife and range cattle manure samples responsible for fecal contamination of Cedar Creek were identified and four fecal sources out of those were quantified for the E. coli concentrations. No significant difference was found upon comparing the E. coli concentration for each species between the genders. Sub-adult cattle demonstrated significantly higher E. coli concentrations than adult cattle. Growth and die-off rates were measured at different temperatures (0degreesC, 10degreesC, 25degreesC, and 50degreesC) and moisture conditions (1%, 25% 56.5% and 83%). E. coli concentrations in cattle and raccoons feces showed highest survivability and growth at 20degreesC out of all the temperatures studied. There was no survival of E. coli from either species at 50degreesC after 24 h. E. coli in cattle and raccoons samples exhibited greater growth at lower, nearly aerobic soil moisture content (25%) for all days compared to nearly anaerobic soil moisture content (83%).

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