Sheep Excreta Research Articles

Different organic composts application in dryland Mollisol:Residual effect and soil CO2 emission.

Organic compost application plays an important role in improving the fertility of Mollisol. However, the effects of different organic composts on carbon sequestration varies greatly and its internal mechanism are unclear. We conducted a field experiment to explore the residual proportion of different organic composts and their effects on carbon emissions in dryland Mollisol in Northeast China. There were a total of seven treatments, including chemical fertilizer control (SNF), organic composts from cattle excreta (CRH), sheep excreta (SHP), chicken excreta (CKN), residue after corn starch production (BCS), residue with crop straws (HRS) and mushroom residue (WMC). We monitored annual soil CO2 flux by static chamber method, as well as the changes of environmental factors and soil dissolved carbon and nitrogen. The regulatory mechanism of organic component characteristics on carbon residual porprotion of organic composts were examined by neural network analysis. The results showed that compared with the SNF treatment, soil dissolved organic carbon (DOC) and extractable organic nitrogen increased by 26.3%-103.5% and 21.4%-150.0%, respectively. The aromaticity of soil DOC was significantly reduced. Heterotrophic respiration flux was mainly affected by soil temperature and DOC content, while its temperature sensitivity was significantly reduced in the CKN treatment. Annual accumulation of heterotrophic respiration increased from 203 g·C·m-2 of the control to 234-334 g·C·m-2 under treatments with organic composts applications, with the CKN and HRS treatments showing the strongest impact. The annual carbon residual proportion of different organic composts in Mollisol was in an order of CRH (91.2%)> WMC (82.9%)> BCS (82.6%)> SHP (78.1%)> CKN (70.2%)> HRS (69.3%). Hemicellulose content and C/N of organic composts were the key factors, which explained 58.8% and 32.9% of the total variations of carbon residual proportion. Organic compost from cattle excreta had higher residual proportion due to lower C/N, hemicellulose content and soluble polyphenol content, and thus did not significantly affect Mollisol heterotrophic respiration. Therefore, the application of organic compost from cattle excreta was more efficient to improve organic carbon in dryland Mollisol.

Greenhouse gas emissions from sheep excreta deposited onto tropical pastures in Kenya

To improve the estimate of greenhouse gas emissions (GHG) from tropical rangelands in sub-Saharan Africa, we measured GHG emissions from sheep excreta over two periods of 51 days on a Kenya rangeland. In addition, we measured GHG emissions from potential hotspots in the landscape linked to sheep grazing: overnight enclosures (“bomas”), where sheep are kept at night to protect them from theft and predators, the areas surrounding sheep bomas, and areas surrounding watering troughs. Results showed a short pulse of CO2 fluxes after sheep urine application and a rapid increase of CH4 fluxes following sheep dung application in both rainy and dry season. However, only small increases of N2O fluxes were observed after dung and urine applications compared to controls without excreta. Elevated N2O fluxes mainly coincided with heavy rainfall. Overall, N2O emission factors (EFs) did not vary across excreta type or seasons, but mean N2O EFs for dung (0.01%) and urine patches (0.02%) were only one tenth of the default EFs from the 2019 IPCC Refinement for dry climate. We did, however, find that bomas and watering troughs are sites of herd concentration that are important sources of GHG emissions in the landscape, and that emissions in these locations can remain elevated for months to years, especially when soil moisture is high. This study contributes to more robust estimates of GHG emissions from African livestock systems, which are fundamental to develop targeted mitigation strategies.

The uptake of selenium by perennial ryegrass in soils of different organic matter contents receiving sheep excreta

Background and aimsThe intake of selenium, an essential element for animals and humans, in ruminants is largely determined by selenium concentration in ingested forages, which take up selenium mainly from soil. Ruminant excreta is a common source of organic fertilizer, which provides both nutrients and organic matter. This study aims to unentangle the unclear effect of applying different types of ruminant excreta in soils of different organic matter contents on selenium uptake by forage.MethodsPerennial ryegrass (Lolium perenne) was grown in soils of different organic matter contents. Urine and/or feces collected from sheep fed with organic or inorganic mineral supplements, including selenium, were applied to the soils. The selenium in the collected samples were analyzed using ICP-MS. The associated biogeochemical reactions were scrutinized by wet chemistry.ResultsThe application of urine and/or feces resulted in either the same or lower selenium concentrations in perennial ryegrass. The excreta type did not affect total selenium accumulation in grass grown in low organic matter soil, whereas in high organic matter soil, feces resulted in significantly lower total selenium accumulation than urine, which was attributed to a possible interaction of selenium sorption in soil and microbial reduction of Se.ConclusionThis one-time excreta application did not increase, but further decrease in some treatments, selenium concentration and accumulation in the perennial ryegrass. Consequently, to increase ruminant selenium intake, supplementing selenium directly to animals is more recommended than applying animal manure to soil, which might drive selenium reduction and decrease selenium uptake by grass.

Low N2O emissions associated with sheep excreta deposition in temperate managed lowland grassland and extensively grazed hill pasture

Nitrous oxide (N2O) is a potent greenhouse gas (GHG) whose emission from soil can be enhanced by ruminant excretal returns in grasslands. The default (Tier 1) emission factors (EF3PRP; i.e. proportion of deposited nitrogen emitted as N2O) for ruminant excreta deposition are associated with a wide range of uncertainties and the development of country-specific (Tier 2) EF3PRP is encouraged. In Ireland, a Tier 2 EF3PRP has been developed for cattle excreta but no data are available for sheep. The aim of this study was to generate data to contribute to the derivation of a Tier 2 EF3PRP for sheep excreta, while assessing the effect of excreta type, grassland type and season of deposition on N2O emissions. An experiment was carried out on two sites in the west of Ireland: a managed lowland grassland (LOW) and an extensively grazed hill pasture (HILL), characterised by mineral and acid peat soils, respectively. For each season, four treatments were applied to the soil in a fully randomized block design: control (C), sheep urine (U), sheep dung (D), and artificial urine (AU). Nitrous oxide fluxes were assessed over a full year following each application of treatments, using a static chambers methodology. Results showed a brief initial peak following each application of U/AU in LOW but not in HILL. Cumulative N2O emissions were significantly higher from the lowland site. Average EF3PRP for combined excreta was negligible on both sites, thus lower than the IPCC Tier 1 EF3PRP. Causes of low emissions are likely to depend on site characteristics (e.g. soil acidity in HILL) and season of application (i.e. ammonia volatilisation in summer). This study showed very low N2O emissions from sheep excretal returns in Irish grasslands and highlighted the importance of developing Tier 2, animal-specific EF3PRP. More experimental grasslands should be assessed to confirm these results.

Low N2o Emissions Associated with Sheep Excreta Deposition in Temperate Managed Lowland Grassland and Extensively Grazed Hill Pasture

Low N2o Emissions Associated with Sheep Excreta Deposition in Temperate Managed Lowland Grassland and Extensively Grazed Hill Pasture

Effects of ground corn and Acacia mearnsii tannin extract supplementation on nitrogen excretion and nitrous oxide emissions from sheep

The nitrogen (N) excreted by grazing animals is the main source of nitrous oxide (N2O) emissions in livestock systems, and feeding strategies to mitigate N excretion should be further studied. The objective of this study was to evaluate the effects of ground corn and tannin extract supplementation on mitigating N2O emissions from sheep excreta. The emissions factor (EF,% of N excreted, which was emitted as N2ON) under the studied conditions were also measured. Two experiments were conducted. In the first one, six Lacaune lambs, with an average BW of 27 ± 3 kg, were distributed in a replicated 3 × 3 Latin square experimental design. The treatments included ad libitum access to ryegrass (Lolium multiflorum Lam.) silage, which contained 21.1 g N/kg DM and was supplemented with 60 g of soybean meal (S), 140 g of ground corn + 60 g of soybean meal (SC) or 140 g of ground corn + 60 g of soybean meal + 40 g/kg Acacia mearnsii tannin extract concentrate (SCT). The daily production of faeces and urine was measured, and samples were collected each day. In the second experiment, urine and faeces were applied to static chambers in the field to determine their N2O emissions. Three replicates of type of excreta from each treatment were included. The nitrogen intake was similar between the treatments, with an average of 18 g/day. The faecal N excretion obtained with tannin extract supplementation was 16% higher (P < 0.01) than that obtained with the S and SC treatments. The daily urinary N excretion from the animals administered ground corn supplementation was 12% lower (P < 0.05) than that from the animals that received only soybean meal, whereas the inclusion of tannins did not effectively induce further decreases in urinary N excretion. The faecal EF of the different treatments was similar, with an average of 0.56 g N2ON/100 g N. The EF of the urine samples averaged 4.8 g N2ON/100 g N. Corn grain supplementation decreased urinary N excretion and N2O emissions from sheep excreta, whereas Acacia mearnsii tannin extract did not effectively improve this response.

Effects of herbivore assemblage on the spatial heterogeneity of soil nitrogen in eastern Eurasian steppe

Abstract The spatial heterogeneity of soil limiting resources is one of the most important factors maintaining biodiversity and ecosystem functions. There is a general concern that herbivore grazing plays a central role in modifying soil resources heterogeneity. However, most studies have examined how large herbivores as a group affect soil heterogeneity. There is limited knowledge about how assemblages of different herbivore species may influence soil heterogeneity, and whether the herbivore assemblage effects might vary with grassland types. Here we conducted a 4‐year grazing experiment to examine the effects of different herbivore assemblages (no grazing; cattle grazing; sheep grazing; and mixed grazing of cattle and sheep) on the spatial heterogeneity of soil N availability across three types of grasslands (meadow steppe, typical steppe and desert steppe) in eastern Eurasian steppe. The results showed that all the herbivore grazing increased the heterogeneity of soil N availability in the three grasslands with different precipitation (only cattle grazing and mixed grazing of cattle and sheep in meadow steppe did not reach a statistically significant level). The consistently increased heterogeneity of soil N availability was primarily due to the effect of animal excreta addition, which weakened in drier grasslands, likely because of the slower excreta decomposition. Moreover, sheep excreta contributed more to soil N heterogeneity than that of other herbivore assemblages, and the effect was statistically significant in meadow steppe and typical steppe with relative high precipitation. Synthesis and applications. Our study indicates that sheep could have larger potential to maintain and enhance grassland heterogeneity than cattle especially in grassland ecosystems with high precipitation. We therefore suggest that managing above‐ground herbivore species is important for conserving and promoting grassland soil heterogeneity, and that the management should also take into account local environmental conditions such as precipitation.

Leaching of benzimidazole antiparasitics in soil columns and in soil columns amended with sheep excreta.

Benzimidazoles are anthelmintics frequently used in sheep farming due to the high susceptibility of these animals to parasitic diseases. Sheep excreta are often disposed onto soils as a fertilizer, and they may contain benzimidazole residues that can contaminate soil and water. This work aimed to assess the leaching behavior of benzimidazole drugs (albendazole, fenbendazole, and thiabendazole) and their metabolites in two Brazilian soils of different textural classifications (sandy and clay), as well as sheep excreta-amended soils, following the OECD 312 Guidelines. Ewes received a single oral dose of 10mgkg-1 b.w. of either albendazole or fenbendazole. The feces were collected at 24, 48, 72, 96, and 120h post-dose, and the parent drugs and their metabolites extracted using the QuEChERS approach and quantified by UHPLC-MS/MS. For the leaching assays, a benzimidazole solution was directly applied onto the soil columns, or an amount of 5g of the medicated sheep feces was distributed over the top of the soil columns. In soil samples, benzimidazoles were extracted by solid-liquid extraction and quantified by UHPLC-MS/MS. For the leaching studies, atrazine was used as a reference substance to determine the relative mobility factor of the analytes of interest. Benzimidazoles were considered slightly to moderately mobile in both soils tested, with a leaching distance of up to 25cm in a 30-cm soil column. Approximately 3 to 6% of the benzimidazoles present in ewe feces were able to leach into the soil columns. This finding is of concern since benzimidazoles are persistent in soil and may pose a risk to soil biota and induce the development of resistant strains of parasites.

BIOGAS PRODUCTION AND In vitro CH4 FROM EXCREMENT OF CATTLE, SHEEP, PIGS AND HEN

&lt;p&gt;The aim of this research was to evaluate the effect of pig, ovine, bovine and hen excreta on biogas production and in vitro methane. Five kg of fresh excreta from cattle, sheep, pigs and hen was used. Each excreta were mixed with water at a ratio of 1: 4. Subsequently, 600 ml of the mixture was poured into bottles of 1-liter nominal capacity, sealed hermetically and kept at 39-40 °C. The total gas production and methane was evaluated. The highest (P&amp;lt;0.05) total gas production was observed in in vitro digesters with hen excreta (27.1 L gas/kg excreta). Methane production and percentage of methane in the gas produced was higher (P&amp;lt;0.05) on in vitro digesters with sheep excreta (8.3 L methane/kg of excreta and 74.7% respectively). The excreta of sheep can be used as a substrate in anaerobic biodigesters due to the potential of methane production.&lt;/p&gt;

A 3-year assessment of nitrous oxide emission factors for urine and dung of grazing sheep in a subtropical ecosystem

PURPOSE: Grazing livestock has strong impact on global nitrous oxide (N₂O) emissions by providing N sources through excreta. The scarcity of information on factors influencing N₂O emissions from sheep excreta in subtropical ecosystems such as those of Southern Brazil led us to conduct field trials in three different winter pasture seasons on an integrated crop–livestock system (ICL) in order to assess N₂O emission factors (EF-N₂O) in response to variable rates of urine and dung. MATERIALS AND METHODS: The equivalent urine-N loading rates for the three winter seasons (2009, 2010, and 2013) ranged from 96 to 478 kg ha⁻¹, and the dung-N rates applied in 2009 and 2010 were 81 and 76 kg ha⁻¹, respectively. Air was sampled from closed static chambers (0.20 m in diameter) for approximately 40 days after excreta application and analyzed for N₂O by gas chromatography. RESULTS AND DISCUSSION: Soil N₂O-N fluxes spanned the ranges 4 to 353 μg m⁻² h⁻¹ in 2009, − 47 to 976 μg m⁻² h⁻¹ in 2010, and 46 to 339 μg m⁻² h⁻¹ in 2013. Urine addition resulted in N₂O-N peaks within for up to 20–30 days after application in the 3 years, and the strength of the peaks was linearly related to the N rate used. Emission factors of N₂O (EF-N₂O, % of N applied that is emitted as N₂O) of urine ranged from 0.06 to 0.34% and were essentially independent of N rate applied. By considering a ratio of N excreted by urine and dung of 60:40, a single combined excretal EF-N₂O of 0.14% was estimated. CONCLUSIONS: Our findings showed higher mean EF-N₂O for sheep urine than that for dung (0.21% vs 0.03%), irrespective of the occurrence or not of urine patches overlap. This value is much lower than default value of 1% of IPCC’s Tier 1 and reinforces the needs of its revision.

Nitrification represents the bottle-neck of sheep urine patch N2O emissions from extensively grazed organic soils

Extensively grazed grasslands are understudied in terms of their contribution to greenhouse gas (GHG) emissions from livestock production. Mountains, moorlands and heath occupy 18% of the UK land area, however, in situ studies providing high frequency N2O emissions from sheep urine deposited to such areas are lacking. Organic soils typical of these regions may provide substrates for denitrification-related N2O emissions, however, acidic and anoxic conditions may inhibit nitrification (and associated emissions from nitrification and denitrification). We hypothesised urine N2O-N emission factors (EFs) would be lower than the UK country-specific and IPCC default value for urine, which is based on lowland measurements. Using automated GHG sampling chambers, N2O emissions were determined from real sheep urine (930 kg N ha−1) and artificial urine (920 kg N ha−1) applied in summer, and from an artificial urine treatment (1120 kg N ha−1) and a combined NO3− and glucose treatment (106 kg N ha−1; 213 kg C ha−1) in autumn. The latter treatment provided an assessment of the soils capacity for denitrification under non-substrate limiting conditions. The artificial urine-N2O EF was 0.01 ± 0.00% of the N applied in summer and 0.00 ± 0.00% of the N applied in autumn. The N2O EF for real sheep urine applied in summer was 0.01 ± 0.02%. A higher flux was observed in only one replicate of the real urine treatment, relating to one chamber where an increase in soil solution NO3− was observed. No lag phase in N2O emission was evident following application of the NO3− and glucose treatment, which emitted 0.69 ± 0.15% of the N applied. This indicates nitrification rates are the bottle-neck for N2O emissions in upland organic soils. We calculated the potential impact of using hill-grazing specific urine N2O EFs on the UK inventory of N2O emissions from sheep excreta, and found a reduction of ca. 43% in comparison to the use of a country-specific excretal EF.

Microbial pathways for nitrous oxide emissions from sheep urine and dung in a typical steppe grassland

The aim of this study was to determine the responses of nitrifiers and denitrifiers to understand microbial pathways of nitrous oxide (N2O) emissions in grassland soils that received inputs of sheep excreta. Sheep dung and synthetic sheep urine were applied at three different rates, simulating a single, double, or triple overlapping of urine or dung depositions in the field. Quantitative PCR and high-throughput sequencing were combined with process-based modeling to understand effects of sheep excreta on microbial populations and on pathways for N2O production. Results showed that emissions of N2O from urine were significantly higher than from dung, ranging from 0.12 to 0.78 kg N2O-N ha−1 during the 3 months. The N2O emissions were significantly related to the bacterial amoA (r = 0.373, P < 0.001) and nirK (r = 0.614, P < 0.001) gene abundances. It was autotrophic nitrification that dominated N2O production in the low urine-N rate soils, whereas it was denitrification (including nitrifier denitrification and heterotrophic denitrification) that dominated N2O production in the high urine-N rate soils. Nitrifier denitrification was responsible for most of the N2O emissions in the dung-treated soils. This study suggests that nitrifier denitrification is indeed an important pathway for N2O emissions in these low fertility and dry grazed grassland ecosystems.

Isolation of tannase producing bacteria from sheep excreta

Isolation of tannase producing bacteria from sheep excreta

Disentangling the effect of sheep urine patch size and nitrogen loading rate on cumulative N2O emissions

Ruminant urine nitrogen (N) concentration and volume are important parameters influencing the size and N loading rate of urine patches deposited to soil. Such parameters can influence N cycling and emissions of the greenhouse gas, nitrous oxide (N2O) from grazed grassland, yet, there is limited information on the effect of these parameters within typical ranges reported for sheep. We used an automated, high-frequency gas monitoring system to investigate N2O emissions from varying urine N application rates and patch sizes under field conditions. Using artificial sheep urine, we manipulated urine N concentration to provide two urine N application rates (4 and 16 g N/L; equivalent to 200 and 800 kg N/ha). We investigated the effect of urine patch size with equal N application rates (4 × 125 cm2 vs 500 cm2, at 200 and 800 kg N/ha) and the effect of patch size with unequal N application rates, but the same total amount of N applied (62.5 mL over 125 cm2 at 800 kg N/ha and 250 mL over 500 cm2 at 200 kg N/ha). Cumulative emissions of N2O generally increased with N loading rate, whether applied as one large urine patch or four smaller ones. Cumulative N2O emissions increased when the N was applied in four smaller urine patches compared with one large patch; this difference was significant at 800 kg N/ha, but not at 200 kg N/ha. When the total amount of N applied was held constant (1 g of N), the amount of N2O released was similar when urine was applied as a high N concentration small patch (800 kg N/ha) compared with a low N concentration large patch (200 kg N/ha). Urine N2O emission factors in this study were, on average, 10 times lower than the IPCC default of 1% for sheep excreta. This research clearly demonstrates that the chemical and physical nature of the urine patch influences N2O emissions, yet further research is required to gather more data on typical sheep urine volumes (individual and daily), urination frequency, urine N concentrations and the typical volumes of soil influenced by urine deposition, to provide more accurate estimates of emissions from sheep grazed pastures.

Sheep Excreta as Source of Nitrous Oxide in Ryegrass Pasture in Southern Brazil

ABSTRACT Livestock urine and dung are important components of the N cycle in pastures, but little information on its effect on soil nitrous oxide (N2O) emissions is available. We conducted a short-term (39-day) trial to quantify the direct N2O-N emissions from sheep excreta on an experimental area of ryegrass pasture growing on a Typic Paleudult in southern Brazil. Four rates of urine-N (161, 242, 323, and 403 kg ha-1 N) and one of dung-N (13 kg ha-1 N) were applied, as well as a control plot receiving no excreta. The N2O-N emission factor (EF = % of added N released as N2O-N) for urine and dung was calculated, taking into account the N2O fluxes in the field, over a period of 39 days. The EF value of the urine and dung was used to estimate the emissions of N2O-N over a 90-day period of pasture in the winter under two grazing intensities (2.5 or 5.0 times the herbage intake potential of grazing lambs). The soil N2O-N fluxes ranged from 4 to 353 µg m-2h-1. The highest N2O-N fluxes occurred 16 days after application of urine and dung, when the highest soil nitrate content was also recorded and the water-filled pore space exceeded 60 %. The mean EF for urine was 0.25 % of applied N, much higher than that for dung (0.06 %). We found that N2O-N emissions for the 90-day winter pasture period were 0.54 kg ha-1 for low grazing intensity and 0.62 kg ha-1 for moderate grazing intensity. Comparison of the two forms of excreta show that urine was the main contributor to N2O-N emissions (mean of 36 %), whereas dung was responsible for less than 0.1 % of total soil N2O-N emissions.

Sheep excreta cause no positive priming of peat-derived CO2 and N2O emissions

Large areas of peatlands in Germany and the Netherlands are affected by drainage and high nitrogen deposition. Sheep grazing is a common extensive management activity on drained peatlands, in particular on nature protection areas. However, input of easily mineralisable material such as sheep excrements could enhance degradation of soil organic carbon (Corg), thereby increasing the effect of these ecosystems on national GHG budgets. Thus, a microcosm experiment on the influence of sheep excreta on GHG emissions from a histic Gleysol with strongly degraded peat was set up. The 15N and 13C stable isotope tracer technique was used to partition sources of CO2 and N2O. Labeled sheep faeces and urine were obtained by feeding enriched material. Undisturbed soil columns were treated with surface application of urine, faeces or mixtures of both in different label combinations to distinguish between direct effects and possible priming effects. Incubation was done under stable temperature and precipitation conditions. Fluxes as well as 15N and 13C enrichment of N2O and CO2, respectively, were measured for three weeks. Addition of sheep excreta increased emission of total CO2 in proportion to the added carbon amounts. There was no CO2 priming in the peat. No effect on CH4 and N2O was observed under the aerobic experimental conditions. The N2O–N source shifted from peat to excreta, which indicates negative priming, but priming was not significant. The results indicate that sheep excreta do not significantly increase GHG emissions from degraded peat soils. Considering the degraded peatland preserving benefits, sheep grazing on peatlands affected by drainage and high nitrogen deposition should be further promoted.

Nitrous oxide emissions from grazed hill land in New Zealand

Sheep and beef cattle grazed hill land represents a potentially large source of nitrous oxide (N2O) emissions globally. However, N2O emissions and associated emission factors for the dominant nitrogen (N) source of excreta N (EF3) are thought to be highly variable due to spatial differences in soil conditions across hill land units (HLUs; defined according to slope, aspect and soil type). Variability is also determined by animal grazing and resting behaviour affecting excretal-N deposition. Knowledge of spatially different EF3 values could be used to improve estimates of N2O emissions from grazed hill land. This paper presents N2O emission factors for sheep urine (SU) and dung (SD) and for beef cattle dung (BD) determined in four regions in New Zealand (NZ) (Waikato, Southern Hawkes Bay, Manawatu and Otago). Urine (spring 2009) or urine and dung (autumn 2011) was applied to low (<12°) and medium (12–25°) slopes in each region. N2O emissions were measured for 3–4 months for urine and for a whole year for dung using a static chamber technique. There were large variations in EF3 between seasons, between regions and between slope classes within a region and season. Over all regions, there was a marginally significant (P=0.08) difference in EF3 for spring 2009-applied SU on low and medium slopes, with EF3 values averaging 0.46% and 0.08%, respectively. In the autumn 2011 trial, there was no significant slope effect, with EF3 averaging 0.12% and 0.11% on low and medium slopes, respectively. By combining the datasets, EF3 for low slopes (0.24 with 95% confidence intervals of between 0.14 and 0.40) was significantly greater (P<0.05) than for medium slopes (0.07% with 95% confidence intervals of between 0.02 and 0.14). EF3 values for BD and SD were not significantly different. The contribution of sheep excreta to NZ national N2O emissions, based on a spatial framework model that disaggregates excreta deposition according to slope class and using the current inventory EF3 values of 1% for urine and 0.25% for dung and assuming that all NZ sheep grazed on hill land, was 6.08Gg N2O in 2012 in NZ. This is considerably higher than the 1.02Gg N2O estimated using the measured EF3 values, 0.24% for urine and 0.06% for dung, from this study. These results suggest that the current IPCC GHG inventory methodology is likely to overestimate N2O emissions from animal grazed hill land.

Response of nitrogen oxide emissions to grazer species and plant species composition in temperate agricultural grassland

Agriculture is an important source of the greenhouse gas nitrous oxide (N2O) and the atmospherically important nitric oxide (NO). We evaluated the effects of different grazers and plant species composition on N2O and NO emissions in temperate grassland. Paddocks were grazed rotationally by either cattle or sheep. Mean N2O emissions were 38.7μg N2O-Nm−2h−1, mean NO emissions 2.4μg NO-Nm−2h−1. Cumulative NO-N emissions were larger for sheep- than for cattle-grazed paddocks. Plant species composition was insignificant compared to the effect of grazers on N oxide emissions. In a controlled application experiment, plots with cattle excreta showed larger N2O emissions than plots with sheep excreta, reaching peak emissions of 1921μg N2O-Nm−2h−1 on cattle urine patches compared to 556μg N2O-Nm−2h−1 on sheep urine patches, related to different N-inputs per excretion. Peak emissions of dung-treated plots were much smaller. The N2O emission factors were 0.4% for cattle urine, 0.5% for sheep urine, 0.05% for cattle dung and 0.09% for sheep dung. N oxide emissions on the paddock scale were larger for sheep- compared to cattle-grazing, despite larger emissions per cattle excretion. We attributed this to the more even spread of sheep excreta compared to cattle excreta.

Extraction of NOx and Determination of Nitrate by Acid Reduction in Water, Soil, Excreta, Feed, Vegetables and Plant Materials

Different methods are available for extracting NOx from different samples. A judicious combination of lead acetate, sodium hydroxide and magnesium chloride has been devised to enable extraction of NOxfrom different samples ensuring removal of potential interfering agents. The method provides over 95 per cent mean recovery with nearly 3 per cent accuracy and precision. Nitrite is determined by Griess reaction, and removed from samples by urea treatment to obviate any interference by nitrite in nitrate determination. Nitrate is determined by acid reduction method with minimum detection limit 0.5 ppm as N. The methods have been applied to selected environmental samples including food materials and excretory products. The average nitrate levels (as ppm N) found in water (0.8), soil (9), human urine (43), sheep excreta (2654), chicken feed (29), radish (270), spinach (222), carrot(194), potato (41), cabbage (11), tomato (2), Bermuda grass (175) and morning-glory leaves (576) have been within safe and documented limits. The average levels of nitrite, as ppm N, have generally ranged from 0.04 to 2.1 with highest content, 13, in sheep fecal matter. The protocol is intended for general use in environmental analysis,toxicological investigations and risk assessments.

Livestock excreta management through vermicomposting using an epigeic earthworm Eisenia foetida

In India, millions of tones of livestock excreta are produced. Our study explores the potential of an epigeic earthworm Eisenia foetida to compost different livestock excreta (cow, buffalo, horse, donkey, sheep, goat and camel) into value added product (vermicompost) at the laboratory scale. Vermicomposting resulted in lowering of pH, electrical conductivity, potassium and C:N ratio and increase in nitrogen and phosphorus contents. Total K was lower in the final cast than in the initial feed. C:N ratios of the vermicomposts ranged from 16.2 ± 2.17 to 75.4 ± 6.84. Microbial activity measured as dehydrogenase activity in buffalo, donkey and camel wastes increased with time up to day 90. But in sheep and goat wastes, maximum dehydrogenase activity was recorded on day 60 and decreased thereafter. The cocoons and hatchlings production by Eisenia foetida in different excreta were also investigated. The greatest number and biomass of hatchlings was recorded in horse excreta followed by cow, goat and sheep excreta. Thus, cow, horse, sheep and goat excreta show potential as good substrates in vermicomposting using Eisenia foetida, although further research is required to explore the feasibility of use of buffalo, donkey and camel excreta in combination with cow/sheep/goat excreta.