Effect of the pig slurry separation techniques on the characteristics and potential availability of N to plants in the resulting liquid and solid fractions

Solid-liquid separation of slurry is used to obtain a solid (SF) and liquid fraction (LF), both used as organic fertilisers. Previous works showed that the separation technique used influences the composition of the resulting SF but no data are available relative to the LF. Four commonly used separation processes were considered e centrifugation, sieving, enhanced settling by the addition of cationic polyacrylamide (PAM-), and sediment settling as well as a recent sequential process e sieving followed by PAM addition to the resulting LF. The resulting LFs and SFs were comprehensively characterised and the amount of N potentially available for plants after incorporation to soil was also evaluated. Except for slurry that was only sieved which was very similar in composition to whole slurry (WS), the SFs and LFs had, respectively, higher and lower, concentrations of nutrients and organic matter (OM) than the WS. The ratio of ammoniacal to total N in the LFs varied from 0.33 to 0.92 whereas the values in the SFs varied between 0.16 and 0.31. The N:P:K ratio was also significantly influenced by the separation technique. Less than 10% of the total N applied in the WS, SFs or LFs was found to be potentially available for plants and, in some LFs, N immobilisation occurred after soil application. Since separation technique strongly influences nutrient distribution between LF and SF, as well as N speciation, the choice of the technique has to consider the final use of the resulting fractions as well as acquisition and operating costs

Quantification of priming and CO2 emission sources following the application of different slurry particle size fractions to a grassland soil

The highest emissions of CO2 from soils and most pronounced priming effect (PE) from soils generally occur immediately after slurry application. However, the influence of different particle size slurry fractions on net soil C respiration dynamics and PE has not been studied. Therefore, a slurry separation technique based on particle sizes was used in the present study. Six distinct fractions (>2000, 425–2000, 250–425, 150–250, 45–150, 250 μm fractions. The overall contribution of slurry C to total CO2 emissions was higher in smaller slurry particle size treatments in the first days after application. The addition of the various slurry fractions to soil caused both significant positive and negative PEs on the soil organic matter mineralization. The timing and type (positive or negative) of PE depended on the slurry particle size. Clearly, farm based separation pre-treatment leading to two or more fractions with different particle sizes has also the potential to reduce or modify short-term CO2 emissions immediately after slurry application to soil

Assessment of CO2 emissions during acidification, storage and after incorporation to soil of pig slurry

RAMIRAN International ConferenceLarge amounts of pig slurry are produced each year in Portugal leading to environmental problems such as water and air pollution. Previous studies have reported that livestock production is the main source of anthropogenic ammonia (NH3) emissions in Europe (Kai et al., 2008) and an important source of greenhouse gases (Weiske and Petersen, 2006). Effluent treatment has been promoted to improve slurry management and to reduce its environmental impact (Sommer and Hutchings, 2001, Fangueiro et al., 2008a). Solid-liquid separation of slurry is a useful tool at the farm level producing valuable fractions, a liquid that can be used for direct fertilisation and a solid fraction that can be composted (Fangueiro et al., 2008b). Alternatively, acidification of slurry has been proposed to reduce ammonia (NH3) emissions during storage and field application (Kai et al., 2008). Previous works (Misselbrook et al., 2005; Fangueiro et al., 2008a) reported that higher NH3 emissions occurred during storage of liquid fraction of slurry or manure with low dry matter content, probably due to a reduced crust formation that decreases NH3 emissions. Hence, acidification of the liquid fraction of slurry is strongly recommended. Slurry acidification is common practice in The Netherlands and Denmark (Schils et al., 1999; Eriksen et al., 2008) but this technology still needs to be improved to avoid hazards. It is expected that this technology will be used in more countries since the European Directive (2001/81/CE) demands a decrease of atmospheric pollutants such as NH3: targets for lower NH3 emissions have been already set in Spain (Castrillon et al., 2009). Nevertheless, the acidification process leads to significant carbon dioxide (CO2) emissions (Vandré and Clemens, 1997). Such CO2 release is problematic when a closed system of slurry acidification is used (when acidified slurry is flushed back to pig houses) since it may lead to foam formation (Vandré and Clemens, 1997; Borst, 2001). Nevertheless, Fangueiro et al. (2010) reported that acidification of slurry or derived fractions led to a decrease in CO2 emissions following soil addition relative to non acidified materials. The aim of the present work was to measure the CO2 emissions during the acidification process of the liquid fraction of pig slurry and its subsequent impact during storage and after soil incorporation

Effect of dairy effluents pre-treatment on N2O emissions and N-organic degradation after soil application

Nitrous oxide (N2O) is a potent greenhouse gas that plays a key role in climatic forcing contributing to the greenhouse effect by about 4 %, and also contributes to stratospheric ozone depletion. Cattle slurries are commonly applied to agricultural soils, inducing an increase of soil nitrous oxide emissions. Therefore, many procedures were developed for slurry pre-treatment in order to improve soil slurry application and reduce nitrogen losses, namely N2O emissions. The aim of this work was to compare N2O emissions and the kinetic of N organic degradation from treated and untreated cattle-slurry after its incorporation in agricultural soils

Separação de sólidos e nutrientes com PAM e bentonite em chorumes bovinos

A separação de sólidos do chorume e a aplicação de agentes floculantes à fracção líquida obtida constituem processos de tratamento deste efluente pecuário que permitem a obtenção de materiais com características distintas que ampliam as opções de utilização e de gestão do chorume. A redução do teor de sólidos e nutrientes na fracção sobrenadante apresenta vantagens em termos de odores, armazenamento, tratamento, aplicação aos solos e irrigação. Este trabalho teve como objectivo avaliar a utilização dos agentes floculantes poliacrilamida (PAM) e bentonite na remoção de sólidos e nutrientes da fracção líquida do chorume de explorações de bovinicultura leiteira. O trabalho experimental decorreu em Vila do Conde durante 2004, numa exploração de bovinicultura leiteira intensiva. O chorume bruto foi sujeito a separação mecânica de sólidos. Posteriormente a fracção líquida obtida foi bombeada para recipientes, e definiram-se 3 tratamentos com 2 repetições: controlo, adição de 200 mg L -1 de PAM e adição de 2 g L -1 de bentonite. Após a aplicação dos floculantes foram recolhidas amostras às fracções sobrenadante e sedimentada nos tempos 0, 2, 4, 20 e 30 horas. Essas amostras foram analisadas relativamente à concentração de N Kjeldahl, P e K totais, N-NH4 + , P solúvel em água, C orgânico solúvel em água, valor de pH e %MS. A separação mecânica do chorume bruto conduziu a uma eficiência de remoção pela fracção sólida obtida de 22, 25, 44 e 21%, respectivamente, dos teores de N Kjeldahl, P total, P solúvel em água e MS. Quanto à capacidade de remoção dos floculantes, a aplicação de PAM conduziu à eficiência de remoção da fracção sobrenadante de 46, 40, 65, 57 e 40%, respectivamente para o N Kjeldahl, P e K totais, P solúvel em água e MS; e a aplicação de bentonite a remoções de 19, 21, 11, 16 e 12%

Influence of two nitrification inhibitors (DCD and DMPP) on annual ryegrass yield and soil mineral N dynamics after incorporation with cattle slurry

Nitrogen (N) losses through nitrate leaching, occurring after slurry spreading, can be reduced by the use of nitrification inhibitors (NIs) such as dicyandiamide (DCD) and 3,4-dimethyl pyrazole phosphate (DMPP). In the present work, the effects of DCD and DMPP, applied at two rates with cattle slurry, on soil mineral N profiles, annual ryegrass yield, and N uptake were compared under similar pedoclimatic conditions. Both NIs delayed the nitrate formation in soil; however, DMPP ensured that the soil mineral N was predominantly in the ammonium form rather than in the nitrate form for about 100 days, whereas with DCD such effect was observed only during the first 40 days after sowing. Furthermore, the use of NIs led to an increase of the drymatter (DM) yields in a range of 32–54% and of the forage N removal in a range of 34–68% relative to the slurry-only (SO) treatment (without NIs). A DM yield of 8698 kg ha21 was obtained with the DMPP applied at the greater rate against only 7444 kg ha21 obtained with the greater rate of DCD (4767 kg ha21 in the SO treatment). Therefore, it can be concluded that DMPP is more efficient as an NI than DCD when combined with cattle slurr

Carbon and nitrogen mineralization of organic wastes from sugarcane distilleries: vinasse and yeast waste

RAMIRAN International ConferenceIn Madeira Island (Portugal) significant amounts of wastes are generated in sugarcane distilleries, namely vinasse (the remaining fermented must after distillation) and yeast waste (the yeast surplus produced during the alcoholic fermentation). These wastes have high organic loads and low pH, leading to serious environmental problems when released directly into natural watercourses or when poorly managed (Hati et al., 2007). As a solution to avoid expensive treatments, both wastes have been used as soil amendment, since they contain important amounts of plant nutrients and organic matter (Resende et al., 2006; Parnaudeau et al., 2008). Indeed, application to soils of vinasse is a common practice in sugarcane cultivated areas and can fully substitute K and partially P on crops fertilization. Nevertheless, additional mineral nitrogen fertilization is needed when vinasse is spread in the soils (Junior et al., 2007; Oliveira et al., 2009). On the other hand, yeast waste has been considered as an excellent potential source of nitrogen for plant nutrition when applied to soils (Rezende et al., 2004). Thus, combined application of both wastes should ensure a more balanced supply of nutrients to plants. However, scarce information is available on the combine use of both wastes as fertilizer. The main objective of this study is to assess the effect of the combined application to soil of both organic materials (vinasse and yeast waste), and to evaluate its subsequent effects on nitrogen mineralization/immobilization process to supply nitrogen to crops and to preserve/restore soil carbon

Influence of the particle size and animal slurry type on the potential of nitrogen mineralization after soil incorporation

RAMIRAN International ConferenceAnimal manures are rich in organic matter and nutrients, namely nitrogen (N) and, consequently, widely applied to soil as organic fertilizers. However, a large part of the nitrogen contained in animal manures is in the organic form and so not directly available for plants. Indeed, organic N has to be mineralized prior to plant uptake (Rees and Castle, 2002). Several manure characteristics as the C:N ratio (Chadwick et al., 2000), the lignin content (Kristensen, 1996) and the NH4 +/organic N ratio (Beauchamp and Paul, 1989) have been suggested as indicators of the plant-available N. More recently, Fangueiro et al. (2008) showed that the potential of N mineralization (PNM) of cattle slurry is inversely correlated with slurry particle size: finest fractions are the particle-size fractions from which N mineralization occurs in slurries whereas coarser fractions are associated with immobilization. Furthermore, Moller et al. (2002) reported that animal diet and anaerobic decomposition during storage in slurry channels and stores affect the slurry particle size distribution. Such information is of great interest since the finest slurry particle size should infiltrate the soil more easily and quickly relative to the coarser slurry particle size that should remain close to soil surface. Furthermore, mechanical slurry separation is now performed in many pig and dairy farms in order to improve slurry management in terms of nutrients utilization and reducing costs related to slurry storage. Slurry separation by screw press leads to a nutrient rich organic solid fraction (0.7– 3.2 mm particles) that may be composted and a liquid fraction that can be used for fertigation. In the present study, three types of slurry (pig, duck and cattle) were separated into 4 slurry particle size fractions (>2000 um, 2000-500 um, 500-100 um, <100 um) in order to assess the influence of the type of slurry and slurry particle size on the PNM after soil incorporation

Impact of cattle slurry treatment by separation and acidification on gaseous emissions after soil application

Objectives: Cattle-slurry management became a priority in many livestock farms and slurry treatment is used to increase the fertilizer value of slurry and/or minimize its environmental impact. Indeed, significant emissions of ammonia (NH3) and greenhouse gases (GHG) as nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) can occur during and after slurry application to soil. Application of acidified slurry or liquid fraction (LF) obtained by solid-liquid separation are two alternatives to raw slurry application that have proven to be efficient to minimize ammonia emissions. However, few is known about its effect on GHG emissions. The aim of the present work was to assess the efficiency of cattle slurry treatment by acidification and/or solid liquid separation to mitigate ammonia (NH3) and greenhouse gases (GHG) emissions following surface application to a sandy loam soil