Greenhouse gas emission from the soils fertilized with liquid pig slurry (LPS) in Tifton 85 bermudagrass pasture in tropical savanna

The application of liquid pig slurry (LPS) to pastures offers potential as a fertilizer but could have a direct influence on soil CO2 emissions. This study evaluated soil carbon dioxide emissions after successive LPS applications to soils under pasture cultivation. The experiment was carried out on ‘Tifton-85’ bermudagrass pasture cultivated in a red-yellow oxisol soil in the municipality of Lucas do Rio Verde-MT, Brazil. Two treatments were evaluated: the control and an application of 20 m3 ha-1 of LPS after each cut of the pasture. The CO2 emissions from the soil were determined using a high-precision infrared gas analyzer. Soil temperature and soil moisture were determined as were micrometeorological variables. The application of LPS had a significant effect on soil C-CO2 flow. The average flow of C-CO2 from the soil for the control treatment and with the application of LPS was 0.236 g C-CO2 m-2 h-1 and 0.291 g C-CO2 m-2 h-1, respectively. The application of LPS increased the accumulated CO2 emissions from the soil by 23.2%. Soil temperature and moisture are the main factors regulating the process of soil CO2 emission. These factors therefore need to be considered when evaluating the impact of LPS application on greenhouse gas emissions

Nitrous oxide (N2O) production in tropical soils cultivated with sugarcane is associated with ammonia-oxidizing bacteria (AOB) and fungal denitrifiers. However, the taxonomic identities and the community diversities, compositions, and structures of AOB and fungal denitrifiers in these soils are not known. Here, we examined the effects of applying different concentrations of an organic recycled residue (vinasse: regular non-concentrated or 5.8-fold concentrated) on the dynamics of AOB and fungal denitrifier community diversity and composition and greenhouse gas emissions during the sugarcane cycle in two different seasons, rainy and dry. DNA was extracted from soil samples collected at six timepoints to determine the dynamics of amoA-AOB and nirK-fungal community diversity and composition by amplicon sequencing with gene-specific primers. Bacterial and archaeal amoA, fungal and bacterial nirK, bacterial nirS and nosZ, total bacteria (16S rRNA) and total fungi (18S rRNA) were quantified by real-time PCR, and N2O and CO2 emissions were measured. The genes amoA-AOB and bacterial nirK clade II correlated with N2O emissions, followed by fungal nirK. The application of inorganic nitrogen fertilizer combined with organic residue, regardless of concentration, did not affect the diversity and structure of the AOB and fungal denitrifier communities but increased their abundances and N2O emissions. Nitrosospira sp. was the dominant AOB, while unclassified fungi were the dominant fungal denitrifiers. Furthermore, the community structures of AOB and fungal denitrifiers were affected by season, with dominance of uncultured Nitrosospira and unclassified fungi in the rainy season and the genera Nitrosospira and Chaetomium in the dry season. Nitrosospira, Chaetomium, Talaromyces purpureogenus, and Fusarium seemed to be the main genera governing N2O production in the studied tropical soils. These results highlight the importance of deciphering the main players in N2O production and demonstrate the impact of fertilization on soil microbial N functions.

HighlightsRZWQM2 was compared with DNDC to predict greenhouse gas emissions.RZWQM2 was applied to simulate the greenhouse gas emissions under manure application.RZWQM2 performed better than DNDC in simulating soil water content and CO2 emissions.Abstract. N management has the potential to mitigate greenhouse gas (GHG) emissions. Process-based models are promising tools for evaluating and developing management practices that may optimize sustainability goals as well as promote crop productivity. In this study, the GHG emission component of the Root Zone Water Quality Model (RZWQM2) was tested under two different types of N management and subsequently compared with the Denitrification-Decomposition (DNDC) model using measured data from a subsurface-drained field with a corn-soybean rotation in southern Ontario, Canada. Field-measured data included N2O and CO2 fluxes, soil temperature, and soil moisture content from a four-year field experiment (2012 to 2015). The experiment was composed of two N treatments: inorganic fertilizer (IF), and inorganic fertilizer combined with solid cattle manure (SCM). Both models were calibrated using the data from IF and validated with SCM. Statistical results indicated that both models predicted well the soil temperature, but RZWQM2 performed better than DNDC in simulating soil water content (SWC) because DNDC lacked a heterogeneous soil profile, had shallow simulation depth, and lacked crop root density functions. Both RZWQM2 and DNDC predicted the cumulative N2O and CO2 emissions within 15% error under all treatments, while the timing of daily CO2 emissions was more accurately predicted by RZWQM2 (RMSE = 0.43 to 0.54) than by DNDC (RMSE = 0.60 to 0.67). Modeling results for N management effects on GHG emissions showed consistency with the field measurements, indicating higher CO2 emissions under SCM than IF, higher N2O emissions under IF in corn years, but lower N2O emissions in soybean years. Overall, RZWQM2 required more experienced and intensive calibration and validation, but it provided more accurate predictions of soil hydrology and better timing of CO2 emissions than DNDC. Keywords: CO2 emission, Corn-soybean rotation, Inorganic fertilization, Manure application, N2O emission, Process-based modeling.

Emissions of N2O, CH4, and CO2 from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N2O, CH4, and CO2 from undisturbed soil plots to the atmosphere were 2.5×109, 4.3×1010, and 3.0×1013 molecules cm-2 s-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N2O increased fourfold after simulated rainfall, suggesting that production of N2O in savanna soils during the rainy season may be an important source for atmospheric N2O. The CH4 flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO2 from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N2O, CH4, CO2, and other trace gases, especially during the rainy season.

Greenhouse gas emissions from coastal freshwater wetlands in Veracruz Mexico: Effect of plant community and seasonal dynamics

Tropical wetlands are important climate regulators. However, their climate regulating function is at risk by land-use conversion for agricultural purposes. In sub-Saharan Africa, studies investigating the effect of land-use change in wetlands and associated soil greenhouse gas (GHG) emissions remain limited. Moreover, the influence of season in GHG emissions with land-use change has hardly been studied. Therefore, we investigated methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) emissions from a Kenyan wetland and adjacent areas converted to farmland during the dry and rainy seasons. Moreover, we assessed which soil parameters drive the variations in GHG emissions. The GHG samples were collected by the static chamber method and analyzed by gas chromatography. For data analysis, we employed an explorative-statistical approach to explain the emission rates' variation and determine which parameters influence the GHG emissions, both as main and interaction effects. The results showed that regardless of the season, there were CH4 emissions (>0.50 mg m−2 h−1) from the wetland when soil organic carbon content was high and uptake (<0.001 mg m−2 h−1) when both soil organic carbon content and soil moisture were low. In the farmland, there was CH4 uptake when soil nitrate‑nitrogen content was high. CO2 emissions did not vary significantly between the land-use types. Instead, emission rates were primarily governed by season. The highest emissions (>175 mg m−2 h−1) during the dry season were attributed to high soil organic carbon content. During the rainy season, emissions hardly exceeded 175 mg m−2 h−1. Regarding N2O, we detected the highest emissions (>5 μg m−2 h−1) from the farmland during the dry season. Overall, this study shows that wetland conversion to farmland encourages CH4 uptake regardless of the season and increases N2O emissions during the dry season. Based on the respective GHG global warming potential, these patterns may pose an increased environmental threat.

Hybrid poplar plantations in Quebec, Canada, are generally established on marginal agricultural lands characterized by low pH and low inherent soil fertility. Here, we tested the hypothesis that two potential organic fertilizer (OF) sources, papermill biosolids (PBs) and liquid pig slurry (LPS), would improve soil quality and the growth performance of hybrid poplars ( Populus trichocarpa × Populus deltoides ), especially if applied in mixtures rather than separately. The fertilizer treatments included an unfertilized control, inorganic fertilizer (IF) (calcium ammonium nitrate and triple superphosphate) and OFs (PBs alone, LPS alone and two combinations of PBs and LPS) applied at two rates. Fertilizers were broadcast within 1 m of tree trunks and unincorporated, to prevent damage to tree roots. Hybrid poplar growth was the greatest in plots fertilized with a combination of PBs and LPS, suggesting that the two OFs complemented themselves and/or interacted to improve soil nutritional quality. PBs were the most efficient at raising soil pH, providing plant‐available Ca and increasing nitrification rates over the long term, whereas LPS provided more readily available NO 3 ‐N, P and K. Applied together, PBs and LPS interacted to provide more extractable P and mineralizable NH 4 ‐N than when applied separately. OFs increased soil biological activity, notably basal respiration, microbial biomass, metabolic quotient and mineral N production rates. Community‐level catabolic profiles of the extractable soil microflora in plots with OFs differed significantly from the control and IF treatments. This implies that surface‐applied OFs may induce fundamental changes to the diversity and composition of microbial communities in the underlying rooting zone. Although this study has shown beneficial effects of OF mixtures on soil quality and hybrid poplar growth, further research should focus on their possible environmental impacts.

Summary A total of 966 cichlids, Cichlasoma urophthalmus, was sampled from three karstic water bodies (cenotes) in the Yucatan Peninsula. Sex ratio was not different from 1. Specimens with ripe eggs were found during the dry and rainy seasons in the inland cenote and during the dry, rainy, and north winds seasons in the two wetland cenotes. With respect to relative fecundity, data show the C. urophthalmus inland population as two- to three-fold greater (53.1 ± 27.7) than the wetland populations (15.7 ± 5.1 and 18.2 ± 3.1). This is attributable to the different breeding strategies of C. urophthalmus populations inhabiting these two types of cenotes. In particular, the ichthyofauna from the two wetlands showed not only higher species richness (17 and 16 species) but also a higher number of potential predators (nine and eight species) as compared to the inland cenote (six species; two potential predators). It is hypothesized that C. urophthalmus adjusts its clutch size and extends its breeding periods as a response to riskier sites as compared to more secure ones; a higher competition for breeding sites and to increased fishing mortality.

Influence of soil properties on N2O and CO2 emissions from excreta deposited on tropical pastures in Kenya

Abstract. The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N2O. Tree species had a significant effect on CO2 and N2O releases but not on CH4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.

Oil palm (Elaeis guineensis Jacq.) production in Indonesia and Malaysia is currently the focus of concern due to its potential impact on the environment via greenhouse gas emissions. Oil palm plantations have been reported to release large quantities of nitrous oxide (N2O) into the atmosphere, which is most likely linked to nitrogen (N) fertilizer use. However, there are still limited studies comparing effects of the type of soil and N fertilizer on N2O and carbon dioxide (CO2) emissions. This study aimed to evaluate the effects of soil types and N fertilizer on N2O and CO2 emissions in oil palm plantations. N2O and CO2 emissions were measured for 15–16 months from 2010–2012 in Tunggal sandy loam soil, Indonesia, and in Simunjan sandy soil and Tatau peat soil, Malaysia. Within each site, treatments with coated fertilizer and conventional fertilizer, and unfertilized with and without tillage, were established. N2O and CO2 fluxes showed high variabilities with seasons, types of soil and fertilizer treatments. The mean of the N2O fluxes from each treatment in the Simunjan sandy soil was the lowest among the three soils, ranging from 0.80 to 3.81 and 1.63 to 5.34 μg N m−2 h−1 in the wet and dry seasons, respectively. The mean of the N2O fluxes from each treatment in the Tunggal sandy loam soil ranged from 27.4 to 89.7 and 6.27 to 19.1 μg N m−2 h−1 in the wet and dry seasons, respectively. The mean of the N2O fluxes was found to be the highest among the three soils in each treatment of the Tatau peat soil, ranging from 131 to 523 and 66.1 to 606 μg N m−2 h−1 in the wet and dry seasons, respectively. The N application rate of coated fertilizer was about half that of conventional fertilizer and was applied as deep placement. In the Tungal soil, coated fertilizer reduced N2O emissions by 31 and 48% in wet and dry seasons, respectively, compared to the conventional fertilizer, and was similar to unfertilized treatment. However, N2O emissions increased in Simunjan and Tatau soils during dry seasons. There was no significant difference between treatments. These results show that N2O and CO2 fluxes in the tropical oil palm plantations were significantly affected by the type of soil, but not always by fertilizer treatments.

The aim of this study was to compare testosterone concentration, body weight, scrotal circumference and age to penis detachment from days 30 to 240 in young Boer goat males (n = 22) born during the dry (n = 11) and the rainy (n = 11) seasons. In the dry season the parameters varied as follows: body weight from 3.7 ± 1.1 to 34.0 ± 4.7 kg, scrotal circumference from 7.9 ± 0.8 to 25.7 ± 2 cm, and testosterone concentration from 259.4 ± 172.4 to 4613.4 ± 2892 pc/mL. In the rainy season parameters varied as follows: body weight from 9.7 ± 2.3 to 28.1 ± 6.9 kg, scrotal circumference from 9.5 ± 1.5 to 22.0 ± 3.0 cm and testosterone from 521.9 ± 311.3 to 3417.9 ± 2021.8 pc/mL. At three months of age, 70% of animals born during the rainy season presented with penis detachment, compared to 67.6% of animals born during the dry season at five months of age. Penis detachment occurred in all males at four and seven months for animals born in the rainy and dry seasons, respectively. There was a positive correlation between testosterone concentration and body weight in the dry (r = 0.30) and rainy (r = 0.43) seasons, between testosterone and scrotal circumference in the dry (r = 0.42) and rainy (r = 0.52) seasons, and between body weight and scrotal circumference in the dry (r = 0.93) and rainy (r = 0.88) seasons. The animals born during the rainy season showed earlier development in all the evaluated parameters than animals born during the dry season. It was found that scrotal circumference is directly correlated to body weight and testosterone concentration. Keywords : Scrotal circumference, testosterone, young male goats, puberty, sexual maturity

Physicochemical parameters of surface water collected from six different points (P1 to P6) on River Sokoto were analysed during January (Dry Season) and August (Rainy Season), 2014 to determine its water quality using standard methods. The highest temperature of 25.6&#176C was recorded by P1 in dry season while P5 recorded the highest value of 29.2&#176C in rainy season. All the water samples were alkaline in dry season with the highest pH value of 8.50 in P5 and the least value of 8.02 in P6 whereas in rainy season, P1, P2 and P3 were slightly acidic while P5 and P6 were slightly neutral and P4 alkaline. The highest values of 510 μS/cm and 850.3 mg/l were recorded from P4 for electrical conductance and hardness respectively in the rainy season whereas in dry season, P5 and P4 had the highest values of 321 μS/cm and 282.8 mg/l respectively. The highest DO and BOD levels in dry season were 1.7 mg/l and 0.7 mg/l respectively in P1 and the least values were 0.7 mg/l and 0.2 mg/l respectively in P5. But in the rainy season, P6 recorded the highest DO value of 0.1 mg/l while P2 and P5 recorded the least value of 0.07 mg/l. For BOD, P5 had the highest value (2.13 mg/l) while P3 had the least value (0.20 mg/l). For COD, the highest value (230 mg/l) was found in P4 and P6 and the least value (30 mg/l) was found in P1 in dry season while in the rainy season, P2 had the highest COD value (1008 mg/l) and P4 had the least value of 32 mg/l. TDS and TSS values generally were higher in the rainy season than in the dry season due to higher amount of floating particles in the rainy season. While P1 and P6 recorded the highest values (800 mg/l and 700 mg/l respectively) in the rainy season, P4 recorded the least value of 100 mg/l in both seasons. The highest Chloride level was found in P4 in the dry (100 mg/l) and rainy (180 mg/l) seasons with the least level in P2 (35 mg/l) in dry season and in P1 and P2 with the least level of 60 mg/l in the rainy season. The highest concentration of Sulphate in P1 (220 mg/l) in dry season was far above the highest concentration (124 mg/l) in the rainy season whereas highest concentration of Nitrate in dry season in P1 (19.7 mg/l) was somehow below the highest concentration in rainy season in P4 (28.1 mg/l). Phosphate and Ammonia had the highest values of 1.77 mg/l and 0.84 mg/l respectively in P5 in dry season while in rainy season, P6 and P4 had the highest values of 0.22 mg/l and 1.20 mg/l respectively. There was significant seasonal variation in some physicochemical parameters and most of the parameters were within permissible limits, thus, making the water suitable for irrigation purposes.

Nitrous oxide, methane, and ammonia emissions from cattle excreta on Brachiaria decumbens growing in monoculture or silvopasture with Acacia mangium and Eucalyptus grandis

Agriculture is the second-largest contributor of greenhouse gasses (GHGs) globally, after fossil fuels combustion. The excessive application of mineral fertilizers and the inadequate disposal of large amounts of livestock waste in agricultural soils result in elevated N2O and CO2 emissions, which surpass 17% of the global GHG emissions.Approximately 1.4 billion tons of cow manure (CM) are produced every year in the EU and current EU policies promote CM incorporation into the soil, as a cost-efficient and sustainable agronomic practice. The European Green Deal urges a 20% reduction in chemical fertilization by 2030 and reuse of organic fertilizers, i.e. cow manure The beneficial use of CM is linked to enhanced soil fertility, soil organic matter content and carbon sequestration.&amp;#160;However, soil organic amendments may fuel soil nutrient transformations and potentially increase nutrient losses i.e. GHG emissions.To test the short-term effects of combined organic and inorganic fertilization on GHG emissions, we conducted a mesocosm experiment using two soil types (Sandy-loam (SL) &amp; Loamy (L))&amp;#160;and including five treatments: Control (C: No fertilization), Urea as Chemical Fertilization in two rates (100U:200 kg/ha &amp; 80U:160 kg/ha), Cow Manure (CM:50 Mg/ha) and the combination of 80U and CM (80U-CM:160 kg/ha Urea &amp; 50 Mg/ha Cow Manure). During a 90-days incubation period, CO2 and N2O flux rates and soil NO-3, NO-2 and NH+4 were measured regularly.&amp;#160;Soil type was the only significant factor (p&amp;#8804;0.05) driving cum. CO2 emissions. A 20% increase of cum. CO2 was found for L soil treatments than SL. The combined treatment 80U-CM had similar emissions to conventional fertilization (100U) that were on average 762 mg/kg C-CO2, approx. 28.5% greater than C (591 mg/kg). CM incorporation led to 19% increase in cum. CO2 emissions than C.Contrary to CO2, soil (p&lt;0.001), fertilization (p&lt;0.001) and their interaction (p=0.002) were significant factors explaining cum. N2O emissions. The SL soil had 60% higher cum. N2O emissions compared to L. The use of CM in L soil decreased (39%), while in SL soil increased (5%) cum N2O emissions, relative to C. A 20% reduction in urea application resulted in 90% and 19% reduction for SL and L soil, respectively when compared to 100U. The combined application 80U-CM increased cum. N2O emissions than CM and 80U and had lower cum. N2O emissions than 100U, for both soils. Soil, fertilization, and their interaction were accounted for statistically significant (p&amp;#8804;0.05) differences in soil NO3- , NO2- and NH4+ availability (AUC) .According to our study, the combined application of 80U-CM cannot be an effective alternative to conventional fertilization (100U), as it generates similar levels of GHG emissions and has lower nutrient (N) supply potential. Furthermore, our preliminary research indicates the need to further quantify the effects of different organic amendments on GHG soil emissions and soil microbial communities.Funding: The BSc and MSc research work by George Kourtidis and Elpida Pasvadoglou, respectively, was supported in part by the Hellenic Foundation for Research and Innovation (HFRI) Post-Doctoral Grant #1053 awarded to Principal Investigator Dr. Georgios Giannopoulos.