• Authors:
    • van Groenigen, J. W.
    • Lubbers, I. M.
    • Paul, B. K.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 3
  • Year: 2012
  • Summary: Earthworms can increase nitrous oxide (N2O) emissions, particularly in no-tillage systems where earthworms are abundant. Here, we study the effect of residue incorporation depth on earthworm-induced N2O emissions. We hypothesized that cumulative N2O emissions decrease with residue incorporation depth, because (i) increased water filled pore space (WFPS) in deeper soil layers leads to higher denitrification rates as well as more complete denitrification; and (ii) the longer upward diffusion path increases N2O reduction to N2. Two 84-day laboratory mesocosm experiments were conducted. First, we manually incorporated maize (Zea mays L.) residue at different soil depths (incorporation experiment). Second, 13C-enriched maize residue was applied to the soil surface and anecic species Lumbricus terrestris (L.) and epigeic species Lumbricus rubellus (Hoffmeister) were confined to different soil depths (earthworm experiment). Residue incorporation depth affected cumulative N2O emissions in both experiments (P similar to<similar to 0.001). In the incorporation experiment, N2O emissions decreased from 4.91 similar to mg similar to N2ON similar to kg-1 soil (surface application) to 2.71 similar to mg similar to N2ON similar to kg-1 soil (4050 similar to cm incorporation). In the earthworm experiment, N2O emissions from L. terrestris decreased from 3.87 similar to mg similar to N2ON similar to kg-1 soil (confined to 010 similar to cm) to 2.01 similar to mg similar to N2ON similar to kg-1 soil (confined to 030 similar to cm). Both experimental setups resulted in dissimilar WFPS profiles that affected N2O dynamics. We also found significant differences in residue C recovery in soil organic matter between L. terrestris (2841%) and L. rubellus (56%). We conclude that (i) N2O emissions decrease with residue incorporation depth, although this effect was complicated by dissimilar WFPS profiles; and (ii) larger residue C incorporation by L. rubellus than L. terrestris indicates that earthworm species differ in their C stabilization potential. Our findings underline the importance of studying earthworm diversity in the context of greenhouse gas emissions from agro-ecosystems.
  • Authors:
    • Jouquet, P.
    • Doan, T.
    • Rumpel, C.
    • Ngo, P.
  • Source: Soil Biology and Biochemistry
  • Volume: 50
  • Year: 2012
  • Summary: The use of organic matter (OM) amendments is widespread in tropical countries and may be beneficial for soil carbon storage. Interactions between earthworms and OM amendments in tropical soils are largely unknown. The aim of this study was to investigate the effect of bioturbation on the quantity and chemical composition of OM in soil amended with compost and vermicompost. Our approach included comparison of soil samples amended with compost, vermicompost or chemical fertilizers in the presence or absence of earthworms during a one-year greenhouse experiment. The soils were submitted to a regular cultivation cycle. After one year, we analysed bulk samples for soil OM elemental composition and characterised its lignin and non-cellulosic carbohydrate components. Our results showed a decrease of the carbon and nitrogen content in soil amended with chemical fertilizers. Vermicompost amendment led to unchanged OC content, whereas the compost amendment increased the soils OC content compared to initial soil. The addition of earthworms reduced OC and N content in soils with organic amendments. This is in contrast to soil amended with mineral fertilizer only, where the presence of earthworms did not have any effect. Bioturbation influenced the lignin signature of the soils, and to a lesser extent the non-cellulosic carbohydrate signature. In conclusion, compost amendment combined with bioturbation influenced the quality and quantity of SOM and as result carbon storage and its biogeochemical cycling in tropical soils. Implications for soil fertility remain to be elucidated.
  • Authors:
    • Pergher, M.
    • Tomazi, M.
    • Pauletti, V.
    • de Moraes, A.
    • Zanatta, J. A.
    • Bayer, C.
    • Dieckow, J.
    • Piva, J. T.
  • Source: Plant and Soil
  • Volume: 361
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims For tropical and subtropical soils, information is scarce regarding the global warming potential (GWP) of no-till (NT) agriculture systems. Soil organic carbon (OC) sequestration is promoted by NT agriculture, but this may be offset by increased nitrous oxide (N2O) emissions. We assessed the GWP of a NT as compared to conventional tillage (CT) in a subtropical Brazilian Ferralsol. Methods From September 2008 to September 2009 we used static chambers and chromatographic analyses to assess N2O and methane (CH4) soil fluxes in an area previously used for 3-4 years as a field-experiment. The winter cover crop was ryegrass (Lolium multiflorum Lam.) while in summer it was silage maize (Zea mays L.). Results The accumulated N2O emission for NT was about half that of CT (1.26 vs 2.42 kg N ha(-1) year(-1), P = 0.06). Emission peaks for N2O occurred for a month after CT, presumably induced by mineralization of residual nitrogen. In both systems, the highest N2O flux occurred after sidedressing maize with inorganic nitrogen, although the flux was lower in NT than CT (132 vs 367 mu g N m(-2) h(-1), P = 0.05), possibly because some of the sidedressed nitrogen was immobilized by ryegrass residues on the surface of the NT soil. Neither water-filled pore space (WFPS) nor inorganic nitrogen (NH (4) (+) and NO (3) (-) ) correlated with N2O fluxes, although at some specific periods relationships were observed with inorganic nitrogen. Soils subjected to CT or NT both acted as CH4 sinks during most of the experiment, although a CH4 peak in May (autumn) led to overall CH4 emissions of 1.15 kg CH4-C ha(-1) year(-1) for CT and 1.08 kg CH4-C ha(-1) year(-1) for NT (P = 0.90). The OC stock in the 0-20 cm soil layer was slightly higher for NT than for CT (67.20 vs 66.49 Mg ha(-1), P = 0.36). In the 0-100 cm layer, the OC stock was significantly higher for NT as compared to CT (234.61 vs 231.95 Mg ha(-1), P = 0.01), indicating that NT resulted in the sequestration of OC at a rate of 0.76 Mg ha(-1) year(-1). The CO2 equivalent cost of agronomic practices was similar for CT (1.72 Mg CO(2)eq ha(-1) year(-1)) and NT (1.62 Mg CO(2)eq ha(-1) year(-1)). However, NT reduced the GWP relative to CT (-0.55 vs 2.90 Mg CO(2)eq ha(-1) year(-1)), with the difference of -3.45 Mg CO(2)eq ha(-1) year(-1) (negative value implies mitigation) being driven mainly by OC sequestration. The greenhouse gas intensity (GHGI, equivalent to GWP/silage yield) was lower for NT than CT (-31.7 vs 171.1 kg CO(2)eq Mg-1 for silage maize). Conclusion As compared to CT, greenhouse gas emissions from a subtropical soil can be mitigated by NT by lowering N2O emissions and, principally, sequestration of CO2-C.
  • Authors:
    • Cao, L.
    • Lobell, D. B.
    • Pongratz, J.
    • Caldeira, K.
  • Source: Nature Climate Change
  • Volume: 2
  • Issue: 2
  • Year: 2012
  • Summary: Crop models predict that recent and future climate change may have adverse effects on crop yields(1,2). Intentional deflection of sunlight away from the Earth could diminish the amount of climate change in a high-CO2 world(3-6). However, it has been suggested that this diminution would come at the cost of threatening the food and water supply for billions of people(7). Here, we carry out high-CO2, geoengineering and control simulations using two climate models to predict the effects on global crop yields. We find that in our models solar-radiation geoengineering in a high-CO2 climate generally causes crop yields to increase, largely because temperature stresses are diminished while the benefits of CO2 fertilization are retained. Nevertheless, possible yield losses on the local scale as well as known and unknown side effects and risks associated with geoengineering indicate that the most certain way to reduce climate risks to global food security is to reduce emissions of greenhouse gases.
  • Authors:
    • Gramig, B.
    • Reeling, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 146
  • Issue: 1
  • Year: 2012
  • Summary: Agricultural ecosystems are a source of greenhouse gas (GHGs) emissions and losses of nutrients to waterways. Several studies have recognized this and have documented the potential to reduce GHG fluxes and nutrient loss to waterways by using carbon offsets to fund the implementation of land retirement and afforestation. However, the ability to use land for both agricultural production and environmental conservation is also important. This study develops a novel analytical framework that is used to examine the cross-media (water and air) environmental effects of implementing offset-funded conservation practices in a working-lands setting. The framework is applied to a case study which examines the extent to which carbon pricing can affect practice implementation costs and the optimal distribution of these practices throughout an agricultural watershed. Results indicate that carbon offsets can reduce conservation practice implementation costs and have the potential to reduce greater amounts of nonpoint source pollution for a given cost of implementation. This conclusion has significant implications for policymaking, particularly with regard to using markets for GHG emissions to achieve water quality improvements where water quality trading or government conservation programs have historically been unsuccessful. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Rafi, A.
    • Asim, M.
    • Akmal, M.
    • Farhatullah
    • Raziuddin
    • Shah, A.
  • Source: Pakistan Journal of Botany
  • Volume: 44
  • Issue: 6
  • Year: 2012
  • Summary: Global climate change is consequence of accumulating greenhouse gases (Carbon) at lower atmosphere which might affects crops growth and yield. Maize is an important summer cereals, grown on considerable area in Pakistan every year. We, therefore, study the delay sowing response with changing climate on maize. Field experiment was conducted at Agronomy Research Farm, Agricultural University Peshawar, Pakistan in a randomized complete block design. Sowing was done from June 8 to July 24, 2010 with ten days intervals. Mazie (cv. Azam) was planted in rows at 0.75 m distance in NS orientations. Crop was raised under the uniform recommended cultural practices. Data regarding days to emergence, tasseling and maturity showed a consecutive decrease when sowing was delayed form June 08 onwards. However, the crop life cycle (i.e. vegetative and reproductive durations) initially remained uniform but expanded for late sowing dates (July). Delay sowing showed an increase in the leaf area index with an abrupt decline for the late sown crop. Nonetheless, plant stand at harvest remained static during the growth for all sowing dates. A stable to moderate reduction was noticed in ear length (cm) when sowings was delayed from Jun 08 onwards. Grain rows cob(-1) did not influence by the delay sowing in the season. Moreover, delay sowing did not show any significant (P<0.05) change for the grain number. However, thousand grains weight was initially remained stable but declined (P<0.05) by delay in sowing. Biological yield, dry matter and grains yield (g m(-2)) revealed almost a similar decreasing trend when sowing was delayed. Dry matter to grain yield relationship was linear (r(2) = 0.95) and revealed a mean loss of 1.65 g m(2) when sowing delayed from June 08 to July 24 in the season. Radiation use efficiency (RUE), the growth function, was also declined by the delay in sowing. We inferred that losses in leaf area indices, ear length and grain weights were basis of the grain yield reduction by changing climate of the growing season which brought a significant disturbance in the vegetative and reproductive phases of the crop life cycle that resulted losses (P<0.05) in grain yield by the late sown crop in the season.
  • Authors:
    • Prior, S.
    • Torbert, H.
    • Way, T.
    • Watts, D.
    • Smith, K.
  • Source: Pedosphere
  • Volume: 22
  • Issue: 5
  • Year: 2012
  • Summary: Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil. This study was conducted to determine the impact of fertilizer sources, land management practices, and fertilizer placement methods on greenhouse gas (CO2, CH4, and N2O) emissions. A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study. The field site was located at the Sand Mountain Research and Extension Center in the Appalachian Plateau region of northeast Alabama, USA, on a Hartsells fine sandy loam (fine-loamy, siliceous, subactive, thermic Typic Hapludults). Measurements of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions followed GRACEnet (greenhouse gas reduction through agricultural carbon enhancement network) protocols to assess the effects of different tillage (conventional vs. no-tillage) and fertilizer placement (subsurface banding vs. surface application) practices in a corn (Zea mays L.) cropping system. Fertilizer sources were urea-ammonium nitrate (UAN), ammonium nitrate (AN) and poultry litter (M) applied at a rate of 170 kg ha(-1) of available N. Banding of fertilizer resulted in the greatest concentration of gaseous loss (CO2 and N2O) compared to surface applications of fertilizer. Fertilizer banding increased CO2 and N2O loss on various sampling days throughout the season with poultry litter banding emitting more gas than UAN banding. Conventional tillage practices also resulted in a higher concentration of CO2 and N2O loss when evaluating tillage by sampling day. Throughout the course of this study, CH4 flux was not affected by tillage, fertilizer source, or fertilizer placement method. These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.
  • Authors:
    • Walker, M. B.
    • Faber, A.
    • Syp, A.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: In this paper, simulations with a Denitrification -Decomposition (DNDC) model were used to evaluate the impact of different management options on carbon (C) sequestration and emission of greenhouse gases: methane (CH 4) and nitrous oxide (N2O). Two cropping systems were analyzed. The first included potato, winter wheat, spring barley and forage maize (P-W-B-M). The second included potato, winter wheat, spring barley with clover and grass mixture (P-W-B-C). In both cropping systems, different farmyard manure (FYM) rates were applied. The application of additional nitrogen (N) using FYM increased the C sequestration, as well as N2O emissions and had a little effect on CH 4 uptake. An estimate into the average annual increases in N2O emissions, which were converted into carbon dioxide (CO2) equivalent emissions with 100-year global warming potential (GWP) multipliers, were offset by 56-144% of the C sequestration, depending on the management option. After 16 years of the experiment, the accumulation of C and N per hectare increased in the soil organic matter (SOM) pool. In P-W-B-M rotation, with manure applied at 325 kg N ha(-1), the accumulation of C increased to 5,760 and N 585 kg ha(-1), respectively. In P-W-B-C rotation, where a higher rate of manure was applied, the increase of C was at 10,796 and N 740 kg ha(-1). The highest influence in the rise of C and N accumulation was in humates. The high value of C sequestration in soil outweighs the emissions of N2O. In P-W-B-M rotations, the rate of applied FYM switched its average annual net GWP balance from net losses to a net sink. In P-W-B-C rotations, the applied FYM increased the annual rate of GHG emissions by 3%. The average annual N2O emissions increased by 44% under P-W-B-C rotation and by 142% under P-W-B-M rotations. Increases in the soil organic carbon (SOC) were by 234% and 408%, respectively, for P-W-B-C and P-W-B-M rotations. Our study showed that usage of FYM should be managed correctly, because applications at high rates have a negative impact on environment.
  • Authors:
    • Chi, S.
    • Li, Z.
    • Han, H.
    • Li, N.
    • Wang, B.
    • Zhao, H.
    • Ning, T.
    • Tian, S.
  • Source: Web Of Knowledge
  • Volume: 7
  • Issue: 12
  • Year: 2012
  • Summary: The objective of this study was to quantify soil methane (CH4) and nitrous oxide (N2O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH4 and N2O flux and soil temperature, moisture, NH4+-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH4 appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N2O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH4 and N2O increased by approximately 0.05 kg CO2 ha(-1) for HTS, 0.02 kg CO2 ha(-1) for RTS and 0.23 kg CO2 ha(-1) for NTS. Soil temperature, moisture, SOC, NH4+-N and pH also changed after conversion to subsoiling. These changes were correlated with CH4 uptake and N2O emissions. However, there was no significant correlation between N2O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region. Citation: Tian S, Ning T, Zhao H, Wang B, Li N, et al. (2012) Response of CH4 and N2O Emissions and Wheat Yields to Tillage Method Changes in the North China Plain. PLoS ONE 7(12): e51206. doi:10.1371/journal.pone.0051206
  • Authors:
    • Fernando, L. K.
    • Banuwa, I. S.
    • Buchari, H.
    • Utomo, M.
    • Saleh, R.
  • Source: Journal of Tropical Soils
  • Volume: 17
  • Issue: 1
  • Year: 2012
  • Summary: Although agriculture is a victim of environmental risk due to global warming, but ironically it also contributes to global greenhouse gas (GHG) emission. The objective of this experiment was to determine the influence of long-term conservation tillage and N fertilization on soil carbon storage and CO2 emission in corn-soybean rotation system. A factorial experiment was arranged in a randomized completely block design with four replications. The first factor was tillage systems namely intensive tillage (IT), minimum tillage (MT) and no-tillage (NT). While the second factor was N fertilization with rate of 0, 100 and 200 kg N ha -1 applied for corn, and 0, 25, and 50 kg N ha -1 for soybean production. Samples of soil organic carbon (SOC) after 23 year of cropping were taken at depths of 0-5 cm, 5-10 cm and 10-20 cm, while CO2 emission measurements were taken in corn season (2009) and soybean season (2010). Analysis of variance and means test (HSD 0.05) were analyzed using the Statistical Analysis System package. At 0-5 cm depth, SOC under NT combined with 200 kg N ha -1 fertilization was 46.1% higher than that of NT with no N fertilization, while at depth of 5-10 cm SOC under MT was 26.2% higher than NT and 13.9% higher than IT. Throughout the corn and soybean seasons, CO2-C emissions from IT were higher than those of MT and NT, while CO2-C emissions from 200 kg N ha -1 rate were higher than those of 0 kg N ha -1 and 100 kg N ha -1 rates. With any N rate treatments, MT and NT could reduce CO2-C emission to 65.2%-67.6% and to 75.4%-87.6% as much of IT, respectively. While in soybean season, MT and NT could reduce CO2-C emission to 17.6%-46.7% and 42.0%-74.3% as much of IT, respectively. Prior to generative soybean growth, N fertilization with rate of 50 kg N ha -1 could reduce CO2-C emission to 32.2%-37.2% as much of 0 and 25 kg N ha -1 rates.