Fertilizer value and greenhouse gas emissions from solid fraction pig slurry compost pellets

Abstract

19Conversion of pig slurry to pellets is a desirable fertilizer option for farmers who want to 20 mitigate environmental pollution from slurry accumulation. The goals of the current 21 investigation were to determine the fertilizer properties of pig slurry solid fraction (SF) pellets 22 and to assess its potential to enhance soil properties in order to reduce ammonia (NH3) 23 volatilization and greenhouse gas (GHG) emissions. Various parameters influence SF-24 based pellet fertilizer effectiveness: bulking agent use during composting, pellet diameter 25 sizing and soil application type (superficially or incorporated into the soil). Two composts 26 from the same pig slurry SF obtained from a screw press separator were prepared: pig SF 27 compost without a bulking agent (SSFC) and pig SF compost with wood chips as the bulking 28 agent (wood chip compost (WCC)). For each compost type, pellets of two different diameters 29 (6 and 8 mm) were produced. A mesocosm experiment, conducted with maize plants, was 30 used to test the fertilizer value of the considered pellets. In total, three compost fertilizers -31 SSFC, WCC and nitrogen: phosphorus: potassium mineral fertilizer 15 : 15 : 15, plus one 32 unfertilized control treatment -were applied at the same N rate (equivalent to 200 kg/ha) 33 using two different methods (surface and soil incorporation). After 65 days, above-ground 34 biomass, roots and soil samples were collected and analysed. Subsequently, a second 35 mesocosm study was undertaken to measure NH3 and GHG emissions released from pellet 36 fertilization. Ammonia volatilization was determined immediately after pellet application, 37 while carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions were 38 monitored for 57 days. Study results indicated that both pellet types were effective slow-39 release fertilizers for maize. Additionally, three actions seemed to make the nutrients 40 contained in pig SF compost pellets more available to plants: addition of a bulking agent 41 before com-posting, use of small diameter pellets and soil incorporation of the fertilizer. 42 43

Food-Based Composts Provide More Soil Fertility Benefits Than Cow Manure-Based Composts in Sandy Soils

“…In addition, the non-industrial food waste compost had the highest concentrations of resin P. This confirms the greater fertilizer value of food-based composts compared to cow manure-based composts, as food waste is high in N and P, e.g., 3% N and 0.41% P in Graunke and Wilkie [33], whereas screened manure solids are high in fiber and low in nutrients [23]. Despite these properties, other manure solid products may provide more fertility than the ones tested in this study, such as solid fraction pig slurry compost pellets that can provide similar N availability as mineral fertilizers [19].…”

“…Compost processing conditions also increase variability among composts, as composting duration, oxygen availability, moisture [17], and additional processing (e.g., vermicomposting, pelletization) affect nutrient content and other properties [18,19]. These conditions vary considerably among operations, although industrial composting facilities reduce this variability with streamlined protocols that produce a more consistent and stable product [14,18].…”

Impacts of different organic amendments on soil degradation and phytotoxicity of metribuzin

“…Some researchers found that the application of soil organic amendments could increase the persistence of herbicides by increasing the sorption process (Barker and Bryson 2002;Wanner et al 2005). Different studies showed that the addition of organic matter including manures, composts, and plant residues to soils is a widely accepted non-chemical approach for improving the soil characteristics as well as the different crop production (Garcia-Gomez et al 2002;Perez-Murcia et al 2006;Bastida et al 2008;Mehdizadeh et al 2013;Pampuro et al 2017a). Cox et al (2000) concluded that the infertile soils had a minimum effect on herbicide movement; therefore, the presence of organic matter can be considered as an important adsorbent for herbicides.…”

Reuse of Animal Manure: A Case Study on Stakeholders’ Perceptions about Pelletized Compost in Northwestern Italy

“…Despite knowledge of the benefits related to composted animal manure's application on soil quality [19,20], soil fertility [21][22][23], and the environment [24,25], this material was increasingly considered as a waste in the Mediterranean regions of Europe [26]. With reference to Italy, application of composted manure is not a common practice [23].…”

“…With reference to Italy, application of composted manure is not a common practice [23]. In this specific geographic area, slurry storage for subsequent land application is the predominant manure management practice, probably due to its simplicity and low cost [23]. However, this technique carries several environmental pollution risks, such as ammonia and greenhouse gas emissions into the atmosphere, nitrate leaching into groundwater, and phosphorous runoff into surface waters [20,27,28].…”