Comparison of Nutrient and Metal Loadings with the Application of Swine Manure Slurries and Their Liquid Separates to Soils

Abstract

The accumulation of phosphorus (P) and metals is a serious concern with the continuous application of manure to agricultural soils. Solid-liquid separation of swine slurry is a promising approach to reduce P and metal loadings through application of separated liquid (SL) as a nutrient source. However, little information is available on nutrient and metal loadings with the application of SL compared with unseparated raw manure (RM). We analyzed element concentrations and calculated nutrient and metal loadings for RM and their respective SL applications, considering an application rate of 100 kg total nitrogen (N) ha -1. Samples of SL were obtained through three separation techniques: (i) centrifugation without a flocculant, (ii) centrifugation with a flocculant, and (iii) rotary press with a flocculant. Irrespective of separation technique, calculated P loadings with the application of SL were only 50 to 70% of that of RM at equivalent rates of total N yet exceeded crop removal rate. In contrast, calculated K and Na loadings with SL application were significantly greater than with RM, indicating a possible build-up of K and Na in soil. Calculated Ca and Mg loadings were significantly greater with RM than with SL. Loadings of Al, As, Ba, Cd, Cr, Fe, Mn, Ni, Pb, Sn, Se, Ti, and V were low, whereas Cu and Zn loadings were above crop removal rates for RM and SL. For solidliquid separation to provide a lasting solution to the problem of P and metal accumulation, the SL must be supplemented with commercial N fertilizer to meet crop N demand. A pplication of swine slurry to agricultural soils as a nutrient source is a commonly practiced option in recycling livestock manure and in reducing synthetic fertilizer inputs for crop production (Choudhary et al., 1996;Edmeades, 2003;Penha et al., 2015). However, long-term applications of swine manure, which are often based on crop nitrogen (N) requirements in Canada, may result in an accumulation of nutrients other than N and non-nutrient metals in soils, which may lead to crop toxicity and environmental problems (Gräber et al., 2005;Møller et al., 2007;Penha et al., 2015;Schoenau and Davis, 2006). Phosphorus (P) is of particular concern because the build-up of P in soils may increase P losses from soils through runoff and leaching (Allen and Mallarino, 2008;Kumaragamage et al., 2011) to waterways, triggering eutrophication, a process primarily controlled by dissolved P concentrations in freshwater (Schindler, 1977). Because inorganic salts are commonly added to animal feed, manures usually contain high concentrations of salts. An increase in soil salinity with continuous application of manure (Li-Xian et al., 2007;Schlegel et al., 2015) can deteriorate soil quality and negatively affect crop growth, which has been of little concern until recently. Micronutrients such as manganese (Mn), copper (Cu), and zinc (Zn), which are routinely added to livestock feed to fulfill nutritional needs and for the prevention of diseases, are required in small amounts by plants and thus m...

Seven years of pig slurry fertilization: impacts on soil chemical properties and the element content of winter barley plants

“…From 2004 to 2007, the application of slurries increased soil concentrations around 1.3 mg Zn kg −1 soil for every 1 kg Zn ha −1 applied, and 0.4 mg Cu kg −1 soil for every 1 kg Cu ha −1 applied (Tables 2 and 4 ), although the amount (kg ha −1 ) of Cu applied (from 2004 to 2007) was around four times less than that of Zn (Table 2 ). These increases are consistent with the results obtained by Kumaragamage et al ( 2016 ), and the mean concentrations of 79.1 mg Zn kg −1 and 22.6 mg Cu kg −1 obtained in 2007 are within the ranges proposed by Barber ( 1995 ) (10–300 mg kg −1 for Zn and 1–50 mg kg −1 for Cu). The total increases are the result of the adsorption of these elements in soils at high pH into positions from which they are not readily displaceable.…”

Evaluation of Physicochemical Separation Characteristics of Pig Manure According to the Type of Solid-Liquid Separator Processes

“…They also show that the Centrifuge (+coagulation agent) had the highest reduction of EC. The near-neutral pH (6.7 to 7.2 units) and widely varied EC (4.9-17.0 mS/cm) are also reflected in studies by Kumaragamage et al (2016) [21] and Vanotti et al (2018) [14]. However, the samples that used coagulation agents showed a little increment in pH that because of the chemical compositions of the coagulant agents but stayed near neutral [11,13,20].…”

Aerated Fluidized Bed Treatment for Phosphate Recovery from Dairy and Swine Wastewater

“…10,11 In some soil types such an application may result in a reduction in crop yield due to excess PO 4 −P, salinity, and micronutrient accumulation over time. 12,13 Excess nutrients in soils degrade water quality through eutrophication of surface waters via runoff, and leaching into groundwater by nitrification. 14,15 Agricultural wastewater can be treated for nutrient recovery by an aerated fluidized bed reactor (aerated-FBR) method that precipitates PO 4 −P and NH 4 −N as struvite (MgNH 4 PO 4 • 6H 2 O), a viable slow release fertilizer.…”

“…Thus, all of their liquid wastes are contained in lagoons or storage/settling tanks, and are commonly discharged to topsoil as fertilizer through spraying. , Wastewater discharged in this manner, as part of a nutrient management plan, has limited benefit as fertilizer because application is imprecise, and the nutrients are not in slow release form . Effluent spraying also results in unnecessary water losses and contributes to greenhouse gas emissions. , In some soil types such an application may result in a reduction in crop yield due to excess PO 4 –P, salinity, and micronutrient accumulation over time. , Excess nutrients in soils degrade water quality through eutrophication of surface waters via runoff, and leaching into groundwater by nitrification. , …”