Cattle Slurry Application Research Articles

Nitrogen oxides and ozone fluxes from an oilseed-rape management cycle: the influence of cattle slurry application

Abstract. This study reports NO, NO2 and O3 mixing ratios and flux measurements using the eddy covariance method during a 7-month period over an oilseed-rape field, spanning an organic and a mineral fertilisation event. Cumulated NO emissions during the whole period were in agreement with previous studies and showed quite low emissions of 0.26 kg N ha−1 with an emission factor of 0.27 %, estimated as the ratio between total N emitted in the form of NO and total N input. The NO emissions were higher following organic fertilisation in August due to conditions favouring nitrification (soil water content around 20 % and high temperatures), while mineral fertilisation in February did not result in high emissions. The ozone deposition velocity increased significantly after organic fertilisation. The analysis of the chemical and turbulent transport times showed that reactions between NO, NO2 and O3 below the measurement height occurred constantly throughout the 7-month period. Following organic fertilisation, the NO ground fluxes were 30 % larger than the NO fluxes at the measurement height (3.2 m), while the NO2 fluxes switched from deposition to emission during certain periods, being negative at the surface and positive at the measurement height. This phenomenon of apparent NO2 emissions appears to be significant during strong NO emissions and high O3 ambient mixing ratios, even on a bare soil during August.

Water flow in soil from organic dairy rotations

SUMMARYManaged grasslands are characterized by rotations of leys and arable crops. The regime of water flow evolves during the leys because of earthworm and root activity, climate and agricultural practices (fertilizer, cutting and cattle trampling). The effects of duration of the leys, cattle trampling and fertilizer practice on the movement of water through sandy loam soil profiles were investigated in managed grassland of a dairy operation. Experiments using tracer chemicals were performed, with or without cattle slurry application, with cutting or grazing, in the 1st and the 3rd year of ley, and in winter rye. Each plot was irrigated for an hour with 18·5 mm of water containing a conservative tracer, potassium bromide; 24 h after irrigation, macropores >1 mm were recorded visually on a horizontal plan of 0·7 m2 at five depths (10, 30, 40, 70 and 100 cm). The bromide (Br−) concentration in soil was also analysed at these depths and the density of the different earthworm species were recorded. The density of macropores was not directly influenced by the factors investigated. The abundance of anecic earthworms was larger after 3 years of ley and was not affected by grazing (trampling or dung pat deposits) or fertilizer practice. The water infiltration estimated from the Br− concentration was not influenced by fertilizer practice and was reduced after 3 years of ley due to settlement, but was greater than that for the arable phase of the rotation. As shown by Br− concentration, preferential flow was induced by the grazing regime. Infiltrating water may bypass the soil matrix under similar or more extreme conditions than in the current experiment. Such hydraulic functioning in the grazing regime is expected to reduce the risk of leaching of nitrate contained in soil water.

Cattle slurry acidification and application method can improve initial phosphorus availability for maize

Background and aimsThe utilization of phosphorus (P) in cattle slurry as a starter fertilizer in maize cropping is poor. To improve this and to obviate the use of additional mineral starter-P fertilization, we examined if slurry acidification, placement strategy and application time could increase maize yield and phosphorus uptake (PU) in the early growth stages.MethodsIn a climate-controlled pot experiment, untreated (pH 6.5) and acidified (pH 5.5 or pH 3.8) cattle slurry was injected in narrow or broad bands two or 30 days before sowing of maize on a coarse sandy and a sandy loam soil and compared with mineral P fertilizer.ResultsAfter broad band slurry injection, the P concentration in maize tissues at the five-leaf stage and the dry matter yield at the seven-leaf stage were equal to or higher than the mineral P fertilizer treatment. Treatments with strongly acidified slurry (pH 3.8) had 49% higher PU at the seven-leaf stage compared to untreated slurry, but only on the sandy soil, suggesting an indirect pH effect on PU. Application time had no effect.ConclusionBroad band slurry injection or strong acidification can improve early-stage growth of maize and potentially obviate the use of mineral P.

Farm compost amendment and non-inversion tillage improve soil quality without increasing the risk for N and P leaching

Farmers have to combine several measures to balance carbon contents in the top soil to preserve soil quality but potentially increasing the risk for N and P losses by leaching. We studied the effect of a combination of several measures on topsoil C content, nutrient leaching and soil quality in a multi-year field trial. Soil quality was defined as the result of the interaction between chemical, physical and biological soil characteristics, and included an assessment of disease suppressiveness as well. Initially, the soil had a suboptimal C content (i.e. 0.81%). Soil organic carbon (SOC) levels were maintained and slightly increased by applying slurry and good agricultural practices such as the use of cover crops and the incorporation of cereal straw (on average +0.04 percentage point). Only with a yearly extra plant-based farm compost amendment SOC levels were substantially increased after a period of four years (on average +0.17 percentage point). This application of 8.3 Mg C ha−1 also improved chemical, physical and biological soil quality. Our research demonstrates that farmers can use compost, for at least 4 years, on top of cattle or pig slurry application to soils with suboptimal C levels to increase C content in the top soil, without inducing higher N and P leaching. Repeated compost application increased the microbial biomass (measured by means of PLFA) and disease suppressiveness against Botrytis cinerea on lettuce. There was no effect on the abundance of the plant-parasitic nematode Pratylenchus penetrans in the soil, nor on disease severity caused by Dickeya solani, Streptomyces scabies and Rhizoctonia solani after a potato cropping. Differences between tillage practices were most obvious in the 0–10cm soil layer as non-inversion tillage (compared to ploughing) resulted in an increase in SOC, Total N, hot-water extractable C and P, plant-available P and K, aggregate stability, earthworm abundance and bacterial and fungal populations in this layer.

Poplar short rotation coppice is not a first choice crop for cattle slurry fertilization: Biomass yield and nitrogen-use efficiency

Little is known about the effect of cattle slurry fertilization on poplar short rotation coppice (SRC). This study addresses the following research questions: (i) is the biomass productivity of poplar SRC responsive to slurry application? (ii) what is the efficiency with which poplar SRC utilizes the N applied in the form of cattle slurry? (iii) does the ratio of carbon (C) to N (C/N) in harvested dry matter vary with rates of N fertilization? Fertilization treatments were: (i) no fertilization (control); (ii) cattle slurry 10mm, i.e. 10Lm−2 (CS10); (iii) cattle slurry 20mm, i.e. 20Lm−2 (CS20); and (iv) industrial fertilizers, consisting in 120kgNha−1 in the form of urea and 120kg P2O5 in the form of superphosphate (IF). The agronomic efficiency of applied N (AEN) varied from 5 to 14kg yield dry matter per kg N applied. The recovery efficiency of applied N (REN, kg N uptake per kg N applied) was merely 7.3–10.6%. The physiological efficiency of N uptake (PEN) was 79–123kg yield dry matter per kg N uptake. The threshold of 0.6% N, which is considered the guide value for high-quality biomass feedstock for combustion, was exceeded with the treatment CS20 in the first harvest cycle. Overall, our findings suggest that poplar SRC is not a first choice crop for cattle slurry application. In fact, N supply determined poor agronomic efficiency, a modest fraction of the N applied was recovered by the crop, and the rise of N concentration in the harvested biomass was detrimental for the quality of the feedstock product for combustion.

Ammonia emission after slurry application to grassland in Switzerland

Abstract Loss of ammonia (NH3) after field application of livestock slurry contributes between 30% and 50% of agricultural NH3 emissions from European countries. The objectives of this study were to re-evaluate NH3 emissions following application of cattle and pig slurry to grassland in Switzerland and to investigate the effectiveness of abatement techniques. In 17 field experiments, NH3 emissions were determined with a micrometeorological approach, relating the emission to the measured concentration by means of atmospheric dispersion modelling. The cattle slurry applied exhibited an average dry matter content of 3.3% (range between 1.0% and 6.7% dry matter). The emission after application of cattle slurry spread with a splash plate (referred to as reference technique) ranged from 10% to 47% of applied Total Ammoniacal Nitrogen (% of TAN) and averaged to 25% of TAN. This range of losses is lower by approx. a factor of two compared to measurements from earlier Swiss experiments. Applications with trailing hose and trailing shoe systems yielded an average reduction of 51% and 53%, respectively, relative to the reference technique. A regression analysis showed that the dry matter content of the slurry and the air temperature are important drivers for NH3 emission.

Changes in P fractions after long-term application of biogas slurry to soils under organic farming

In the present field study, the effects of applying biogas slurry for 25 years on soil microbiological and soil chemical properties were investigated in comparison with the application of raw cattle slurry. An on-farm research approach was used with pairwise comparison of neighboring fields, taking samples at a high spatial resolution from two biodynamic farms down to 10 cm. Texture, soil organic C (SOC), total N and P, microbial biomass C, N, and P as well as P fractions were determined by different extraction procedures. Application of biogas slurry had no significant effects on SOC, total N, or microbial biomass C, N, and P. Clay and pH effects outweighed site-specific differences for most properties. Biogas slurry increased the fractions of plant-available inorganic phosphate (+66 % more Olson-Pi) and of Ca-associated phosphates (+40 % 1 M HCl-Pi) at the expense of hardly soluble Fe and Al phosphates (-25 % 6 M HCl-Pi). This is in line with the observation that biogas slurry contains significantly more H2O-Pi and 1 M HCl-Pi than raw slurry. The long-term application of biogas slurry had no negative impacts on any of the soil properties analyzed.

Nutrient, metal and microbial loss in surface runoff following treated sludge and dairy cattle slurry application to an Irish grassland soil

Treated municipal sewage sludge (“biosolids”) and dairy cattle slurry (DCS) may be applied to agricultural land as an organic fertiliser. This study investigates losses of nutrients in runoff water (nitrogen (N) and phosphorus (P)), metals (copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr)), and microbial indicators of pollution (total and faecal coliforms) arising from the land application of four types of treated biosolids and DCS to field micro-plots at three time intervals (24, 48, 360h) after application. Losses from biosolids-amended plots or DCS-amended plots followed a general trend of highest losses occurring during the first rainfall event and reduced losses in the subsequent events. However, with the exception of total and faecal coliforms and some metals (Ni, Cu), the greatest losses were from the DCS-amended plots. For example, average losses over the three rainfall events for dissolved reactive phosphorus and ammonium-nitrogen from DCS-amended plots were 5 and 11.2mgL−1, respectively, which were in excess of the losses from the biosolids plots. When compared with slurry treatments, for the parameters monitored biosolids generally do not pose a greater risk in terms of losses along the runoff pathway. This finding has important policy implications, as it shows that concern related to the reuse of biosolids as a soil fertiliser, mainly related to contaminant losses upon land application, may be unfounded.

Effect of cattle slurry on soil and herbage chemical properties, yield, nutrient balance and plant species composition of moderately dry Arrhenatherion grassland

There is increasing pressure to apply cattle slurry on Arrhenatherion grasslands in Central Europe, but intensive manuring can decrease their natural value. We searched for an N application rate which represents an acceptable compromise between farming requirements for high soil fertility and adequate herbage production, environmental protection requirements for balanced applications of nutrients and nature conservation requirements for species-rich grasslands. We applied different annual rates of cattle slurry (0, 60, 120, 180, 240kg Nha−1) on moderately dry Arrhenatherion grasslands over six years.Slurry application positively affected soil fertility by increasing pH, as well as P, K and Mg availability, without any effect on organic C and the total N content. The mean annual herbage yield was 2.58, 3.56, 4.40, 5.75 and 6.09tha−1 in 0, 60, 120, 180 and 240 treatments, respectively. Concentrations of N, P and K in herbage slightly increased with slurry application, while the concentration of Ca decreased. There was no surplus of N, K and Ca up to an N application rate of 120kgha−1, and there was only a slight surplus of P and Mg. In S3 and S4 treatments, the main change in vegetation was an increase in graminoids cover, accompanied by a decrease in the cover of legumes and short forbs, without any significant effect on the species richness of vascular plants. Slurry application at annual rates up to 120Nha−1 seems to be an acceptable compromise, and we recommend setting this limit for application of cattle slurry on Arrhenatherion grasslands.

The Effect of Chemical Amendments Used for Phosphorus Abatement on Greenhouse Gas and Ammonia Emissions from Dairy Cattle Slurry: Synergies and Pollution Swapping

Land application of cattle slurry can result in incidental and chronic phosphorus (P) loss to waterbodies, leading to eutrophication. Chemical amendment of slurry has been proposed as a management practice, allowing slurry nutrients to remain available to plants whilst mitigating P losses in runoff. The effectiveness of amendments is well understood but their impacts on other loss pathways (so-called ‘pollution swapping’ potential) and therefore the feasibility of using such amendments has not been examined to date. The aim of this laboratory scale study was to determine how the chemical amendment of slurry affects losses of NH3, CH4, N2O, and CO2. Alum, FeCl2, Polyaluminium chloride (PAC)- and biochar reduced NH3 emissions by 92, 54, 65 and 77% compared to the slurry control, while lime increased emissions by 114%. Cumulative N2O emissions of cattle slurry increased when amended with alum and FeCl2 by 202% and 154% compared to the slurry only treatment. Lime, PAC and biochar resulted in a reduction of 44, 29 and 63% in cumulative N2O loss compared to the slurry only treatment. Addition of amendments to slurry did not significantly affect soil CO2 release during the study while CH4 emissions followed a similar trend for all of the amended slurries applied, with an initial increase in losses followed by a rapid decrease for the duration of the study. All of the amendments examined reduced the initial peak in CH4 emissions compared to the slurry only treatment. There was no significant effect of slurry amendments on global warming potential (GWP) caused by slurry land application, with the exception of biochar. After considering pollution swapping in conjunction with amendment effectiveness, the amendments recommended for further field study are PAC, alum and lime. This study has also shown that biochar has potential to reduce GHG losses arising from slurry application.

Investigating sources and sinks for ammonia exchanges between the atmosphere and a wheat canopy following slurry application with trailing hose

Ammonia exchanges between the atmosphere and terrestrial ecosystems are composed of several pathways including exchange with the soil, the litter, the plant surfaces (cuticle) and through the stomata. In this study, the fate of nitrogen in the different pools (soil and plant) was analyzed with the aim of determining the sources and sink of atmospheric ammonia after slurry application on a wheat canopy. To do this, we measured ammonia exchanges between a winter wheat canopy and the atmosphere following cattle slurry application with a trailing hose. From 12 March to 8 April in Grignon near Paris, France, the ammonia fluxes ranged from an emission peak of 54,300 NH3 ngm−2s−1 on the day of slurry application (with a median during the first 24h of 5990 NH3 ngm−2s−1) to a deposition flux of −600 NH3 ngm−2s−1 (with a median during the last period of −16 NH3 ngm−2s−1). The ammonia compensation points were evaluated for apoplasm, foliar bulk, root bulk and litter bulk tissue, as well as for soil surface. Ammonia emission potentials defined by the ratios between the concentration in [NH4+] and [H+] for each N ecosystem pool were in the same order of magnitude for the plant decomposed in apoplastic liquid, green leaf bulk tissue and cuticle, respectively, averaging at 73, 160 and 120; in green leaf bulk tissues, the emission potential decreased gradually from 230 to 78 during the period after slurry application, while in the dead leaf bulk tissues considered as litter, the emission potential reached a maximum of 50,200 after application stabilized at around 20000. The dynamic of the emission potential for roots was similar to the ammonium concentration in the first two centimeters of the soil, with a maximum of 820 reached two days after application and a minimum of 44 reached three weeks later. The surfatm-NH3 model interpreted the emission and deposition fluxes by testing soil surface resistance. We conclude that emission of the first day application was driven by climatic conditions and ammonia concentration at the soil surface, with no surface resistance and with only soil surface emission potential. On the next three days, the ammonia emission originated from the soil surface with the growth of a dry surface layer inducing surface resistance and regulated by slurry infiltration. The following days need a more detailed description of soil surface processes and the integration of vegetation exchanges (stomatal and cuticle pathways), particularly in the last period, in order to explain the ammonia deposition.

Cattle Slurry Fertilization to Giant Reed (Arundo donax L.): Biomass Yield and Nitrogen Use Efficiency

Although giant reed (Arundo donax L.) is regarded as a promising energy crop for Mediterranean environments, its efficiency in utilizing nitrogen (N) fertilizers is still largely unexplored. This study addresses the following research questions: (i) What is the effect of cattle slurry application on giant reed productivity? (ii) does giant reed use efficiently the N applied in the form of cattle slurry? (iii) does the ratio of carbon (C) to N (C/N) in harvested biomass vary with rates N supply? To explore these questions, a field experiment was carried out over 5 years in the low Po Valley, Northern Italy. Fertilization treatments annually applied were the following: (i) no fertilization (control); (ii) cattle slurry 10 mm, i.e., 10 L m−2 (CS10); and (iii) cattle slurry 20 mm, i.e., 20 L m−2 (CS20). Compared to the control, the cattle slurry supply substantially increased yield and yield stability of giant reed. The physiological efficiency of applied N (PEN) was 216 kg aboveground DM per kg N uptake for the favorable years 2009, 2010, and 2011. Giant reed produced a lot of biomass per kg of N uptake, therefore limiting the amount of fertilizers needed for its cultivation. The recovery efficiency of applied N (REN) varied from 0.12 to 0.39. The agronomic efficiency of applied N (AEN) varied from 18 to 51 kg aboveground DM per kg N applied, with considerable year-to-year variation. Finally, the N content of harvested biomass always remained below the threshold of 0.6 % N, which is considered the guide value for high-quality biomass feedstock for combustion.

Single and combined application of two-phase olive mill waste and dairy cattle slurry to soil: Short-term effects on N and C dynamics

Two-phase olive mill waste (TPOMW) and dairy cattle slurry (CS) are two organic materials with low economic value and limited potential for reutilization despite their high concentrations of nitrogen (N) and organic matter. A laboratory incubation for ca. 100 d was performed to assess the short-term N and carbon (C) dynamics in a soil amended with TPOMW, CS and a mixture of both materials in order to: (i) explore the potential benefits of mixing TPOMW with CS to promote mineral N immobilization and avoid nitrate leaching, and (ii) assess the potential for increased soil C stocks after TPOMW, CS or TPOMW+CS application. Our results clearly showed that the combined application of TPOMW+CS caused N immobilization; hence, it contributes to tying up the applied N, resulting in a decrease of critical N leaching, which is usually observed after CS application. No clear N mineralization was observed in the TPOMW+CS treatment during the incubation period.It appears that an application of 30 Mg ha−1 of TPOMW is enough to decrease net N mineralization from applied CS, as the C:N ratio of the mixture TPOMW+CS is 27. More than 40% of the TPOMW-derived C remained in the soil at the end of the experiment in treatments with single and combined application of TPOMW+CS, indicating that such materials have the potential to increase C stocks in soil. It can be concluded that a combined application of TPOMW+CS is of interest to maintain the CS-derived N in organic form during a longer time period and minimize risks of nitrate leaching, although further studies are necessary to define a better TPOMW:CS ratio which allows a proper plant N uptake.

Short-term effects of biogas digestate and cattle slurry application on greenhouse gas emissions affected by N availability from grasslands on drained fen peatlands and associated organic soils

Abstract. A change in German energy policy has resulted in a strong increase in the number of biogas plants in Germany. As a consequence, huge amounts of nutrient-rich residues, the by-products of the fermentative process, are used as organic fertilizers. Drained peatlands are increasingly used to satisfy the huge demand for fermentative substrates (e.g., energy crops, grass silage) and the digestate is returned to the peatlands. However, drained organic soils are considered as hot spots for nitrous oxide (N2O) emissions and organic fertilization is additionally known to increase N2O emissions from managed grasslands. Our study addressed the questions (a) to what extent biogas digestate and cattle slurry application increase N2O and methane (CH4) fluxes as well as the mineral nitrogen use efficiency (NUEmin) and grass yield, and (b) how different soil organic matter contents (SOMs) and nitrogen contents promote the production of N2O. In addition NH3 volatilization was determined at one application event to obtain first clues with respect to the effects of soil and fertilizer types. The study was conducted at two sites within a grassland parcel, which differed in their soil organic carbon (SOC) and N contents. At each site (named Corg-medium and Corg-high) three plots were established: one was fertilized five times with biogas digestate, one with cattle slurry, and the third served as control plot. On each plot, fluxes of N2O and CH4 were measured on three replicates over 2 years using the closed chamber method. For NH3 measurements we used the calibrated dynamic chamber method. On an annual basis, the application of biogas digestate significantly enhanced the N2O fluxes compared to the application of cattle slurry and additionally increased the plant N-uptake and NUEmin. Furthermore, N2O fluxes from the Corg-high treatments significantly exceeded N2O fluxes from the Corg-medium treatments. Annual cumulative emissions ranged from 0.91 ± 0.49 to 3.14 ± 0.91 kg N ha−1 yr−1. Significantly different CH4 fluxes between the investigated treatments or the different soil types were not observed. Cumulative annual CH4 exchange rates varied between −0.21 ± 0.19 and −1.06 ± 0.46 kg C ha−1 yr−1. Significantly higher NH3 losses, NUEmin and grass yields from treatments fertilized with biogas digestate compared to those fertilized with cattle slurry were observed. The total NH3 losses following the splash plate application were 18.17 kg N ha−1 for the digestate treatments and 3.48 kg N ha−1 for the slurry treatments (36 and 15% of applied NH4+–N). The observed linear increase of 16 days' cumulative N2O–N exchange or annual N2O emissions, with mean groundwater level and ammonium application rate, reveals the importance of site-adapted N fertilization and the avoidance of N surpluses in Corg-rich grasslands.

The effect of the nitrification inhibitor dicyandiamide (DCD) on nitrous oxide and methane emissions after cattle slurry application to Irish grassland

Application of cattle slurry to grassland can lead to gaseous losses of nitrogen (N). The dynamics of ammonia (NH3) emissions are well documented, but emissions of nitrous oxide (N2O) and other trace gases from land application of cattle slurry, are not as well understood. Nitrification inhibitors such as dicyandiamide (DCD) help to retain soil N in the ammonium (NH4+) form, which is expected to result in reduced N loss and increased N use efficiency. Emissions of methane (CH4) could potentially be affected by DCD, since the enzyme ammonia monooxygenase (AMO), which DCD is thought to inhibit, can oxidise CH4 as well as NH3. The objective of this study was to investigate the impacts of DCD on N2O and CH4 emissions from grassland soils after slurry application. At one experimental site, Johnstown Castle (JC), County Wexford, Ireland, slurry was applied in March, June and October for two years, at a rate of 33m3ha−1, by either bandspread (BS) or splashplate (SP) application methods, with and without DCD. A second site at Hillsborough (HB), County Down, Ireland, was treated in the same way for one year only, using the SP application method. Emissions of N2O and CH4 were measured using static chambers. Over the entire experiment DCD significantly reduced cumulative N2O emissions by 47 and 70% at both sites. Slurry spreading method had no significant effect on direct N2O emissions and there was no effect of DCD on CH4 emissions throughout the experiment. Using an emission factor for indirect N2O emissions of 1%, modelled losses of NH3 through volatilisation, resulted in an estimated 13 times greater indirect than direct N2O emissions. The results suggest that, under typical Irish field conditions, DCD can be used to decrease direct N2O emissions, without increasing CH4 emissions, and bandspreading can be used as a method of decreasing NH3 volatilisation, without increasing direct N2O or CH4 emissions. Since direct N2O emissions were relatively small, targeting indirect N2O emissions through mitigation of NH3 volatilisation and nitrate (NO3−) leaching could be an effective way of decreasing total N2O emissions from slurry application at these sites.

An assessment of nitrification inhibitors to reduce nitrous oxide emissions from UK agriculture

A trial was conducted consisting of 14 experiments across sites in England of contrasting soil type and annual rainfall to assess the effectiveness of nitrification inhibitors (predominantly dicyandiamide (DCD) but limited assessment also of 3, 4-dimethylpyrazole phosphate (DMPP) and a commercial product containing two pyrazole derivatives) in reducing direct nitrous oxide (N2O) emissions from fertilizer nitrogen (N), cattle urine and cattle slurry applications to land. Measurements were also made of the impact on ammonia (NH3) volatilization, nitrate (NO3−) leaching, crop yield and crop N offtake. DCD proved to be very effective in reducing direct N2O emissions following fertilizer and cattle urine applications, with mean reduction efficiencies of 39, 69 and 70% for ammonium nitrate, urea and cattle urine, respectively. When included with cattle slurry a mean, non-significant reduction of 56% was observed. There were no N2O emission reductions observed from the limited assessments of the other nitrification inhibitors. Generally, there were no impacts of the nitrification inhibitors on NH3 volatilization, NO3− leaching, crop yield or crop N offtake. Use of DCD could give up to 20% reduction in N2O emissions from UK agriculture, but cost-effective delivery mechanisms are required to encourage adoption by the sector. Direct N2O emissions from the studied sources were substantially lower than IPCC default values and development of UK country-specific emission factors for use in inventory compilation is warranted.

Application of cattle slurry containing Mycobacterium avium subsp. paratuberculosis (MAP) to grassland soil and its effect on the relationship between MAP and free-living amoeba

Slurry from dairy farms is commonly used to fertilize crops and pastures. This mixture of manure, urine and water can harbor multiple microbial pathogens among which Mycobacterium avium subsp. paratuberculosis (MAP) is a major concern. Persistence of MAP in soil and infection of soil Acanthamoeba was evaluated by culture, real-time IS900 PCR, and by staining of amoeba with acid-fast and vital stains comparing soils irrigated with MAP-spiked or control dairy farm slurry. MAP DNA was detected in soil for the 8 month study duration. MAP was detected by PCR from more soil samples for plots receiving MAP-spiked slurry (n=61/66) than from soils receiving control slurry (n=10/66 samples). Vital stains verified that intracellular MAP in amoeba was viable. More MAP was found in amoeba at the end of the study than immediately after slurry application. There was no relationship between MAP presence in soil and in amoeba over time. Infection of amoeba by MAP provides a protected niche for the persistence and even possibly the replication of MAP in soils. As others have suggested, MAP-infected amoeba may act like a “Trojan horse” providing a means for persistence in soils and potentially a source of infection for grazing animals.

Ammonia and greenhouse gases emission from impermeable covered storage and land application of cattle slurry to bare soil

Handling a large volume of livestock wastes in intensive farm systems could lead to adverse environmental effects, such as excessive load of nutrients to the soil and gaseous losses into the atmosphere. Land spreading of animal manure is one of the sources of ammonia (NH3) volatilization in Europe. Livestock emissions from manure management in the form of greenhouse gases (GHG), i.e., methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O), amount to 15% of the total agricultural emissions. Therefore, it is important to address gas emissions during storage and following slurry land application to reduce the swapping of emissions from one stage of the manure management continuum to the next one. In this study, NH3 and GHG emissions were estimated from flexible bag storage and following cattle slurry band spreading and incorporation to soil. For this, the mass-balance integrated horizontal flux (IHF) technique was used based on NH3 concentration measurements from masts supporting passive flux samplers (PFS) at different heights and GHG concentrations from grab air samples. Furthermore, the backward Lagrangian stochastic (bLS) technique was compared with NH3 emission estimates from the IHF technique along the manure management continuum. On the whole, NH3 and GHG emissions were considered low from the flexible bag storage compared to those from uncovered lagoons reported in the literature. Slurry removal from storage led to higher NH3 and N2O emissions, representing 73% and 75% of total loss in storage, respectively. After slurry band application to soil, NH3 emission peaked within the first 10h. In overall, lower NH3 emissions were registered in land in the current study in comparison with studies testing broadcast application. Slurry land application led to higher CO2 and N2O emissions than covered storage, contributing to 75% and 99% of total emissions, respectively. Regarding results from the bLS technique, NH3 estimates were lower than expected, possibly due to the low emissions found following NH3 abatement strategies carried out in storage and fertilization stages, and insufficient plot coverage by the PFS under changing wind directions. Under occasional NH3 emissions due to manure management operations, the use of multiple downwind points in bLS resulted in more accurate results and better plot coverage compared to a single point. Average NH3 concentration and wind direction within 24h could result in uncertain bLS estimates under changing wind directions. Overall, the flexible bag storage was an effective method of gas emission mitigation in outdoor slurry storage. Slurry band spreading to bare soil lowered NH3 emissions, but a delay in incorporating slurry to soil could have reduced the efficacy of incorporation on NH3 abatement.

It is not worthwhile to fertilize sweet sorghum (Sorghum bicolor L. Moench) with cattle slurry: Productivity and nitrogen-use efficiency

Sweet sorghum (Sorghum bicolor L. Moench) is a viable alternative to maize when irrigation water is unavailable or too expensive. In areas with intensive livestock activities animal slurries are predominantly applied to maize. Although sweet sorghum is fairly investigated species, little is know about the efficiency with which the crop can use nitrogen (N) applied in the form of cattle slurry. Then, a field experiment was devised to explore the following research questions: (i) what is the effect of cattle slurry and industrial fertilizers on sweet sorghum productivity? (ii) which is the N-use efficiency for cattle slurry and industrial fertilizers applied to sweet sorghum? The study was conducted in the years from 2008 to 2012 (five years) in the alluvial plain of the Po Valley, Northern Italy. The fertilization treatments applied annually were: (i) no fertilization (control); (ii) industrial fertilizers 120kgNha−1, applied in the form of urea, +52kgP ha−1, applied in the form of superphosphate, (IF); (iii) cattle slurry 10mm, i.e. 10Lm−2 (CS10); and (iv) cattle slurry 20mm, i.e. 20Lm−2 (CS20). The indigenous soil N supply varied from 112 to 243kgNha−1. The experiment was not irrigated. The observed average annual yields were, in decreasing order: 34.6MgDMha−1 in 2008, 31.7 in 2011, 29.5 in 2009, 27.9 in 2010 and 27.2 in 2012. Physiological efficiency applied N (PEN, kg yield increase per kgN uptake), recovery efficiency applied N (REN, kgN uptake increase per kgN applied) and agronomic efficiency of applied N (AEN, kg yield increase per kgN applied) were evaluated in this study. In the range of observed values the PEN was 63kg DM yield per kgN uptake, the REN varied from 0 to 0.33 and the AEN was zero in all the years of experiment. Fertilization tends to increase N uptake but not yield nor stem juice sugar content. Our findings indicate that under conditions of good soil fertility, sweet sorghum should be considered poorly suited to receive cattle slurry application, due to the absence of yield gain and to the low N-use efficiency. Moreover, the high N uptake achieved by the crop with no fertilization, combined with the modest REN suggest the animal slurry should rather be applied to crops possessing higher efficiency in utilizing N applied with fertilizers. Nevertheless, the frugality of sweet sorghum should be considered a virtue in the light of the increasing interest in reducing the input for energy crop production.

Influence of long-term application of organic and inorganic fertilizers on soil properties

This study assesses the effect of long-term (59 years) application of organic and inorganic fertilizers on soil organic matter and enzyme activity. Total organic C, total organic N, hot water soluble C, microbial biomass C and dehydrogenase activity were evaluated in soil from the long-term field experiment in Prague-Ruzyně (Orthic Luvisol, clay loam). Total organic C and N increased significantly in soils treated with organic fertilizers (farmyard manure, compost) and in soils with a combination of organic and mineral NPK fertilizers (manure + NPK, compost + NPK, cattle manure + straw + NPK) compared to soil treated with inorganic fertilizer, cattle slurry + straw and non-fertilized control. Farmyard manure significantly increased hot water soluble C compared to the control. Dehydrogenase activity was significantly increased by all treatments compared to control. The results indicate that additions of organic matter from various sources differ in the effects on soil organic matter and biological activity. The effect of manure was the most favourable; long-term application of cattle slurry + straw is rather similar to mineral fertilization.