I.P. O'Halloran

University of Guelph, XIA, Ontario, Canada

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Publications (9)13.69 Total impact

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    Yutao Wang, I.P. O'Halloran, T.Q. Zhang, Q.C. Hu, C.S. Tan
    Soil Science Society of America Journal 03/2015; 79:672-680. DOI:10.2136/sssaj2014.07.0307 · 2.00 Impact Factor
  • Nutrient Cycling in Agroecosystems 12/2014; DOI:10.1007/s10705-014-9643-8 · 1.73 Impact Factor
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    Canadian Journal of Plant Science 11/2014; DOI:10.4141/CJPS-2014-229 · 0.92 Impact Factor
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    ABSTRACT: There has been an increased research interest towards developing appropriate environmental soil P tests for identifying soils sufficiently high in P to be of concern to water quality. The objectives of this study were to evaluate the relationships between various soil test P (STP) measures, and to assess the suitability of these STPs and derived indices of degree of P saturation (DPS) as indicators of soluble P losses (assessed as water extractable P (WEP)) from Ontario soils. A total of 391 surface (0–20 cm) soil samples were collected across the province to represent the diverse physical and chemical properties of agricultural soils in Ontario. Significant relationships were generally found between the tested STPs. Among all measured STPs and DPSs, soil Fe-oxide coated filter paper strip P (FeO-P) and DPSOl (Olsen-P/(Olsen-P + PSI)) had the strongest non-linear relationships with soil WEP concentration (r2 values of 0.88 and 0.82, respectively), suggesting these measures may be useful as indicators of soil P losses for Ontario soils. The soil WEP concentrations were significantly correlated to P extractable by the Olsen and the Mehlich-3 methods (r2 = 0.72 for both extractants). In addition, DPSM3-2 (Mehlich-3 P)/(Mehlich-3 Al + Mehlich-3 Fe) and DPSM3-3 [Mehlich-3 P/(Mehlich-3 Al)] were highly promising indicators of soil P losses for agricultural soils in Ontario.
    Geoderma 11/2014; DOI:10.1016/j.geoderma.2014.11.001 · 2.51 Impact Factor
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    ABSTRACT: Congreves, K. A., Voroney, R. P., O'Halloran, I. P. and Van Eerd, L. L. 2013. Broccoli residue-derived nitrogen immobilization following amendments of organic carbon: An incubation study. Can. J. Soil Sci. 93: 23-31. Cole crops, compared with many other crops, can pose a high risk of N losses after harvest due to substantial quantities of readily mineralizable N in crop residues. Organic C amendments (OCA) may reduce N losses via immobilization; however, the synchrony of OCA decomposition and cole crop residue N mineralization is crucial. A soil incubation study evaluated net N and C mineralization of broccoli residue-derived N or fertilizer-derived N with three OCAs: wheat straw, yard waste, or used cooking oil, to predict N immobilization and the potential to mitigate post-harvest N losses. By the 56th d of incubation, broccoli residue mineralized 67.0 mg N kg(-1). In the broccoli residue-derived N treatments, wheat straw, yard waste, and used cooking oil significantly reduced the quantity of net N mineralization by 16.9, 12.3, and 86.0 mg N kg(-1), respectively. The net N mineralization data were fitted to a first-order exponential model, and the overall trend of OCA was negative, indicating immobilization, whether N was derived from broccoli residue or fertilizer. The order of effect from OCAs on N immobilization corresponded to the order of effect on net C mineralization, where wheat straw and yard waste were lower than used cooking oil. In broccoli residue treatments, compared with fertilizer, higher N immobilization occurred for used cooking oil, and higher net C mineralization occurred for used cooking oil and yard waste. The higher N immobilization and net C mineralization suggest that broccoli residue produced a synergistic effect on the decomposition of used cooking oil. Additionally, both broccoli residue and used cooking oil treatments had synchronous peaks of net C mineralization at 4 d. This study provides evidence to warrant field studies to confirm that the application of organic C, especially used cooking oil, after cole crop harvest may be a beneficial management practice to minimize soil N losses.
    Canadian Journal of Soil Science 02/2013; 93(1):23-31. DOI:10.4141/cjss2011-092 · 1.00 Impact Factor
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    ABSTRACT: A 2 year field experiment evaluated liquid manure application methods on the movement of manure-borne pathogens (Salmonella sp.) and indicator bacteria (Escherichia coli and Clostridium perfringens) to subsurface water. A combination of application methods including surface application, pre-application tillage, and post-application incorporation were applied in a randomized complete block design on an instrumented field site in spring 2007 and 2008. Tile and shallow groundwater were sampled immediately after manure application and after rainfall events. Bacterial enumeration from water samples showed that the surface-applied manure resulted in the highest concentration of E. coli in tile drainage water. Pre-tillage significantly (p < 0.05) reduced the movement of manure-based E. coli and C. perfringens to tile water and to shallow groundwater within 3 days after manure application (DAM) in 2008 and within 10 DAM in 2007. Pre-tillage also decreased the occurrence of Salmonella sp. in tile water samples. Indicator bacteria and pathogens reached nondetectable levels within 50 DAM. The results suggest that tillage before application of liquid swine manure can minimize the movement of bacteria to tile and groundwater, but is effective only for the drainage events immediately after manure application or initial rainfall-associated drainage flows. Furthermore, the study highlights the strong association between bacterial concentrations in subsurface waters and rainfall timing and volume after manure application.
    Canadian Journal of Microbiology 04/2012; 58(5):668-77. DOI:10.1139/w2012-038 · 1.18 Impact Factor
  • Soil Science Society of America Journal 01/2012; 76(1):220. DOI:10.2136/sssaj2011.0175 · 2.00 Impact Factor
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    ABSTRACT: Phosphorus (P) loss from agricultural land in surface runoff can contribute to eutrophication of surface water. This study was conducted to evaluate a range of environmental and agronomic soil P tests as indicators of potential soil surface runoff dissolved reactive P (DRP) losses from Ontario soils. The soil samples (0- to 20-cm depth) were collected from six soil series in Ontario, with 10 sites each to provide a wide range of soil test P (STP) values. Rainfall simulation studies were conducted following the USEPA National P Research Project protocol. The average DRP concentration (DRP30) in runoff water collected over 30 min after the start of runoff increased (p < 0.001) in either a linear or curvilinear manner with increases in levels of various STPs and estimates of degree of soil P saturation (DPS). Among the 16 measurements of STPs and DPSs assessed, DPS(M3) 2 (Mehlich-3 P/[Mehlich-3 Al + Fe]) (r2 = 0.90), DPS(M3)-3 (Mehlich-3 P/Mehlich-3 Al) (r2 = 0.89), and water-extractable P (WEP) (r2 = 0.89) had the strongest overall relationship with runoff DRP30 across all six soil series. The DPS(M3)-2 and DPS(M3)-3 were equally accurate in predicting runoff DRP30 loss. However, DPS(M3)-3 was preferred as its prediction of DRP30 was soil pH insensitive and simpler in analytical procedure, ifa DPS approach is adopted.
    Journal of Environmental Quality 09/2010; 39(5):1771-81. DOI:10.2134/jeq2009.0504 · 2.35 Impact Factor
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