Advanced Processing of Food Waste Based Digestate for Mitigating Nitrogen Losses in a Winter Wheat Crop

The anaerobic digestion of food waste converts waste products into ‘green’ energy. Additionally, the secondary product from this process is a nutrient-rich digestate, which could provide a viable alternative to synthetically-produced fertilisers. However, like fertilisers, digestate applied to agricultural land can be susceptible to both ammonia (NH3) and nitrous oxide (N2O) losses, having negative environmental impacts, and reducing the amount of N available for crop uptake. Our main aim was to assess potential methods for mitigating N losses from digestate applied to a winter wheat crop and subsequent impact on yield. Plot trials were conducted at two UK sites, England (North Wyke-NW) and Wales (Henfaes-HF), to assess NH3 and N2O losses, yield and N offtake following a single band-spread digestate application. Treatments examined were digestate (D), acidified-digestate (AD), digestate with the nitrification inhibitor DMPP (D+NI), AD with DMPP (AD+NI), and a zero-N control (C). Determination of N losses was conducted using wind tunnels for NH3, and static manual and automatic chambers for N2O. The N offtake in both grain and straw was also measured. Ammonium nitrate (NH4NO3) fertiliser N response plots (from 75 to 300 kg N ha−1) were included to compare yields with the organic N source. Cumulative NH3-N losses were 27.6 % from D and D+NI plots and 1.5 % for AD and AD+NI of the total N applied, a significant reduction of 95 % with acidification. Cumulative N2O losses varied between 0.13 and 0.35 % of the total N applied and were reduced by 50 % with the use of DMPP. Grain yields for the digestate treatments were 7.52 – 9.21 and 7.23 – 9.23 t DM ha−1 at HF and NW, respectively. Yields were greater from the plots receiving acidified‐digestate relative to the non-acidified treatments but the differences were not significant. The yields (as a function of the N applied with each treatment) obtained for the digestate treatments ranged between 84.2 % (D+NI) and 103.6 % (D) of the yields produced by the same N rate from an inorganic source at HF. Advanced processing of digestate reduced N losses providing an environmentally sound option for N-management

Effects of urease and nitrification inhibitors on soil N, nitrifier abundance and activity in a sandy loam soil

Inhibitors of urease and ammonia monooxygenase can limit the rate of conversion of urea to ammonia and ammonia to nitrate, respectively, potentially improving N fertilizer use efficiency and reducing gaseous losses. Winter wheat grown on a sandy soil in the UK was treated with urea fertilizer with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT), the nitrification inhibitor dicyandiamide (DCD) or a combination of both. The effects on soil microbial community diversity, the abundance of genes involved in nitrification and crop yields and net N recovery were compared. The only significant effect on N-cycle genes was a transient reduction in bacterial ammonia monooxygenase abundance following DCD application. However, overall crop yields and net N recovery were significantly lower in the urea treatments compared with an equivalent application of ammonium nitrate fertilizer, and significantly less for urea with DCD than the other urea treatments

Influence of ruminal methane on digesta retention and digestive physiology in non-lactating dairy cattle

Enteric methane (CH4) production is a side-effect of herbivore digestion, but it is unknown whether CH4 itself influences digestive physiology. We investigated the effect of adding CH4 to, or reducing it in, the reticulorumen (RR) in a 4 × 4 Latin square experiment with rumen-fistulated, non-lactating cows, with four treatments: (i) control, (ii) insufflation of CH4 (iCH4), (iii) N via rumen fistula, (iv) reduction of CH4 via administration of bromochloromethane (BCM). DM intake (DMI), apparent total tract digestibility, digesta mean retention times (MRT), rumen motility and chewing activity, spot breath CH4 emission (CH4exhal, litre/kg DMI) as well as CH4 dissolved in rumen fluid (CH4RRf, μg/ml) were measured. Data were analysed using mixed models, including treatment (or, alternatively, CH4exhal or CH4RRf) and DMI relative to body mass0·85 (rDMI) as covariates. rDMI was the lowest on the BCM treatment. CH4exhal was highest for iCH4 and lowest for BCM treatments, whereas only BCM affected (reduced) CH4RRf. After adjusting for rDMI, CH4RRf had a negative association with MRT in the gastrointestinal tract but not in the RR, and negative associations with fibre digestibility and measures of rumination activity. Adjusting for rDMI, CH4exhal had additionally a negative association with particle MRT in the RR and a positive association with rumen motility. Thus, higher rumen levels of CH4 (CH4exhal or CH4RRf) were associated with shorter MRT and increased motility. These findings are tentatively interpreted as a feedback mechanism in the ruminant digestive tract that aims at mitigating CH4 losses by shortening MRT at higher CH4

Inventario de emisiones de amoníaco de la producción pecuaria de las Regiones de Los Lagos y de Los Ríos, Chile

This paper presents the first inventory of ammonia emissions from livestock production in Los Lagos and Los Ríos Regions of Chile. The inventory was focused in this area because is where cattle production is concentrated. This study aimed to quantify the amount of N losses due to ammonia volatilization from livestock production in these regions of the country, and to provide its spatial representation identifying their main sources. Calculations have been carried out for 1997 and 2007, and also projections to 2017 and 2027 were obtained. Calculated emissions were 6097 and 6206 t NH3-N for 1997 and 2007, respectively. Major sources of NH3-N emissions were cattle accounting for more than 85%, followed by horses and pigs. Farm management practices as grazing, housing, manure storage and land spreading of manure accounted for 87%, 9%, 3%, and 2%, respectively, of total annual emissions. Projections suggest that emissions could increase up to 6344 and 6516 t NH3-N for 2017 and 2027, respectively. Emissions are much lower than those reported for developed European countries. However, intensification of cattle production systems may lead to an increase of ammonia emissions which could impact the temperate forest of Southern Chile characterized by low nutrient fluxes.Este artículo presenta el primer inventario de emisiones de amoníaco de la producción pecuaria de las Regiones de Los Lagos y Los Ríos de Chile, porque esta área concentra la producción chilena de ganado bovino. Este estudio tuvo como objetivos cuantificar las pérdidas de N por volatilización de amoníaco emitidas desde la producción animal en estas regiones del país, y proveer su representación espacial identificando las principales fuentes de emisión. Los cálculos fueron realizados para 1997 y 2007; y desde el año base se proyectaron emisiones para los años 2017 y 2027. Las emisiones calculadas fueron 6097 y 6206 t NH3-N para 1997 y 2007, respectivamente. Las principales fuentes de emisión fueron los bovinos con más del 85% de las emisiones, seguido por equinos y porcinos. Prácticas de manejo de las explotaciones pecuarias como el pastoreo, la estabulación de ganado, el almacenamiento y la aplicación de desechos aportaron el 87%, 9%, 3% y 2%, respectivamente, del total de las emisiones anuales. Las proyecciones sugieren que las emisiones pueden alcanzar las 6344 y 6516 t NH3-N para el 2017 y 2027, respectivamente. Estas emisiones son mucho menores que las reportadas por algunos países europeos desarrollados. Sin embargo, la intensificación de los sistemas productivos ganaderos puede conllevar al aumento en las emisiones de amoníaco, las cuales pueden provocar un impacto en los bosques templados del sur de Chile caracterizados por bajos flujos de nutrientes

Pérdidas de nitrógeno bajo diferentes frecuencias e intensidades de pastoreo en un suelo volcánico del sur de Chile

Chilean livestock production systems have intensified over the last years, with increasing amounts of N fertilizer inputs creating the potentiality for environmental damage through N pollution of water and air, so that alternative production strategies have been developed to reduce such environmental impacts. This study assesses N losses under different grazing frequencies and intensities on permanent pasture ( Lolium perenne L., Festuca arundinacea Schreb., Dactylis glomerata L., and Trifolium repens L.) on an Andisol in Southern Chile. Four grazing strategies were evaluated: frequent-heavy (FH), frequent-light (FL), infrequent-heavy (IH), infrequent-light (IL), and a no grazing control (C) treatment, and each with three replicates in a randomized complete block design. Results of the experiment indicate that N leaching losses were greater in the FH treatment (58.7 kg available N ha -1 ; p < 0.05) and with most of the leaching occurring in spring (39%). On average, N ammonia (NH 3 ) losses were 10% greater in the frequent grazing treatments in relation to the infrequent grazing treatments, since there were no significant differences (P ≤ 0.05) among individual grazing events for FH, FL and IH. Results indicate that grazing frequency affects leaching losses while grazing intensity affects ammonia emissions from the grassland. Grazing with dairy cows in Southern Chile should consider this environmental constraint to ensure sustainable production over time.Los sistemas chilenos de producción ganadera se han intensificado en los últimos años con el uso creciente de fertilizantes que aportan nitrógeno (N), creando el potencial de daño ambiental a través de la contaminación del agua y el aire con N, de manera que se han diseñado estrategias alternativas de producción con el objetivo de reducir este potencial impacto. El presente estudio busca determinar las pérdidas de N bajo diferentes frecuencias e intensidades de pastoreo en una pradera permanente ( Lolium perenne L., Festuca arundinacea Schreb., Dactylis glomerata L., y Trifolium repens L.) en un Andisol del sur de Chile. Se evaluaron cuatro estrategias de pastoreo: frecuente-intenso (FH), frecuente-laxo (FL), infrecuente- intenso (IH), infrecuente-laxo (IL), y un control (C) o tratamiento sin pastoreo, cada uno con tres repeticiones en un diseño de bloques completos al azar. Las pérdidas de N por lixiviación fueron mayores en el tratamiento FH (59 kg N disponible ha-1 ; P ≤ 0,05) donde la mayor parte de las pérdidas ocurrieron en la primavera (39%). En promedio, las pérdidas de amoniaco (NH3) fueron 10% más altas en los tratamientos frecuentes en relación a los tratamientos infrecuentes, ya que entre los pastoreos individuales FH, FL e IH no hubo diferencia significativa (P ≤ 0,05). Los resultados indican que la frecuencia de pastoreo afecta las pérdidas por lixiviación mientras que la intensidad del pastoreo afecta las emisiones de amoniaco desde la pradera. El pastoreo con vacas de lechería en el sur de Chile debería considerar estas limitaciones ambientales para asegurar una producción sustentable en el tiempo