• Authors:
    • Lamb, J. A.
    • Fassbinder, J.
    • Baker, J. M.
  • Source: BioEnergy Research
  • Volume: 7
  • Issue: 2
  • Year: 2014
  • Summary: Corn stover removal, whether for silage, bedding, or bioenergy production, could have a variety of environmental consequences through its effect on soil processes, particularly N2O production and soil respiration. Because these effects may be episodic in nature, weekly snapshots with static chambers may not provide a complete picture. We adapted commercially available automated soil respiration chambers by incorporating a portable N2O analyzer, allowing us to measure both CO2 and N2O fluxes on an hourly basis through two growing seasons in a corn field in southern Minnesota, from spring 2010 to spring 2012. This site was part of a USDA multilocation research project for five growing seasons, 2008-2012, with three levels of stover removal: zero, full, and intermediate. Initially in spring 2010, two chambers were placed in each of the treatments, but following planting in 2011, the configuration was changed, with four chambers installed on zero removal plots and four on full removal plots. The cumulative data revealed no significant difference in N2O emission as a function of stover removal. CO2 loss from the full removal plots was slightly lower than that from the zero removal plots, but the difference between treatments was much smaller than the amount of C removed in the residue, implying loss of soil carbon from the full removal plots. This is consistent with soil sampling data, which showed that in five of six sampled blocks, the SOC change in the full removal treatments was negative relative to the zero removal plots. We conclude that (a) full stover removal may have little impact on N2O production, and (b) while it will reduce soil CO2 production, the reduction will not be commensurate with the decrease in fresh carbon inputs and, thus, will result in SOC loss.
  • Authors:
    • Zgorelec, Z.
    • Bilandzija, D.
    • Kisic, I.
  • Source: Agriculturae Conspectus Scientificus
  • Volume: 79
  • Issue: 1
  • Year: 2014
  • Summary: Soil carbon stocks are highly vulnerable to human activities (such as tillage), which can decrease carbon stocks significantly. These activities break down soil's organic matter and some carbon is converted to carbon dioxide (CO 2). A part of CO 2 (a greenhouse gas that is one of the main contributor to global warming) is lost from the soil by soil respiration (soil CO 2 efflux). The aim of our study is to determine the soil carbon loss by soil CO 2 efflux under different tillage treatments. The experimental site is characterized by continental climate. Field experiment with six different tillage treatments usually used in this area was set up on Stagnic Luvisols in Daruvar, central lowland Croatia in 1994 with investigation aim on determination of soil degradation by water erosion and later, in 2011, expanded to the research on soil CO 2 efflux. Tillage treatments differed in tools that were used, depth and direction of tillage. Tillage treatments were: black fallow (BF), ploughing up/down the slope to 30 cm (PUDS), no-tillage (NT), ploughing across the slope to 30 cm (PAS), very deep ploughing across the slope to 50 cm (VDPAS) and subsoiling (50 cm) plus ploughing (30 cm) across the slope (SSPAS). Field measurements of soil CO 2 concentrations were conducted during one year (n=14) from November 2011 till November 2012, when cover crop was corn ( Zea mays L.). Preliminary soil sampling for determination of soil total carbon content was conducted in April 2011. This paper presents results of soil total carbon content in the soil surface layer (0-30 cm), the variations of CO 2-C efflux during the year, soil carbon loss by CO 2-C efflux and correlation between soil total carbon content and CO 2-C efflux. The range of soil surface total carbon content varied from 19083.7 kg/ha at BF treatment up to 31073.6 kg/ha at SSPAS treatment. The treatment with the lowest average measured CO 2-C efflux was BF. The average CO 2-C efflux at BF treatment was 7.9 kg CO 2-C/ha/day where CO 2-C efflux varied from 2.3 kg CO 2-C/ha/day up to 22.6 kg CO 2-C/ha/day. The treatment with the highest average measured CO 2-C efflux was NT. Range of CO 2-C efflux at NT treatment varied from 7.8 kg CO 2-C/ha/day up to 65.8 kg CO 2-C/ha/day and the average CO 2-C efflux was 24.4 kg CO 2-C/ha/day. Daily soil total carbon loss by soil respiration ranged from 0.04% at BF treatment up to 0.09% at NT treatment. Soil CO 2-C efflux was fully positively correlated with soil total carbon content (r=0.91). After all mentioned, it can be stated that in these agro-ecological conditions, best tillage practice in sustainable plant production in terms of the lowest daily soil total carbon loss (0.06%) by soil respiration is ploughing to 30 cm (PUDS and PAS). Still, it is necessary to conduct the total soil carbon balance in the future research for better understanding of soil carbon gains and losses.
  • Authors:
    • Bonin, C. L.
    • Lal, R.
  • Source: GCB Bioenergy
  • Volume: 6
  • Issue: 1
  • Year: 2014
  • Summary: Biofuel crops may help achieve the goals of energy-efficient renewable ethanol production and greenhouse gas (GHG) mitigation through carbon (C) storage. The objective of this study was to compare the aboveground biomass yields and soil organic C (SOC) stocks under four crops (no-till corn, switchgrass, indiangrass, and willow) 7years since establishment at three sites in Ohio to determine if high-yielding biofuel crops are also capable of high levels of C storage. Corn grain had the highest potential ethanol yields, with an average of more than 4100Lha(-1), and ethanol yields increased if both corn grain and stover were converted to biofuel, while willow had the lowest yields. The SOC concentration in soils under biofuels was generally unaffected by crop type; at one site, soil in the top 10cm under willow contained nearly 13Mg Cha(-1) more SOC (or 29% more) than did soils under switchgrass or corn. Crop type affected SOC content of macroaggregates in the top 10cm of soil, where macroaggregates in soil under corn had lower C, N and C:N ratios than those under perennial grasses or trees. Overall, the results suggest that no-till corn is capable of high ethanol yields and equivalent SOC stocks to 40cm depth. Long-term monitoring and measurement of SOC stocks at depth are required to determine whether this trend remains. In addition, ecological, energy, and GHG assessments should be made to estimate the C footprint of each feedstock.
  • Authors:
    • Castellano, M. J.
    • Sawyer, J. E.
    • Jeske, E. S.
    • Hofmockel, K. S.
    • Drijber, R. A.
    • Bach, E. M.
    • Brown, K. H.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 4
  • Year: 2014
  • Summary: Global maize production alters an enormous soil organic C (SOC) stock, ultimately affecting greenhouse gas concentrations and the capacity of agroecosystems to buffer climate variability. Inorganic N fertilizer is perhaps the most important factor affecting SOC within maize-based systems due to its effects on crop residue production and SOC mineralization. Using a continuous maize cropping system with a 13 year N fertilizer gradient (0-269kg Nha(-1)yr(-1)) that created a large range in crop residue inputs (3.60-9.94 Mgdry matter ha(-1)yr(-1)), we provide the first agronomic assessment of long-term N fertilizer effects on SOC with direct reference to N rates that are empirically determined to be insufficient, optimum, and excessive. Across the N fertilizer gradient, SOC in physico-chemically protected pools was not affected by N fertilizer rate or residue inputs. However, unprotected particulate organic matter (POM) fractions increased with residue inputs. Although N fertilizer was negatively linearly correlated with POM C/N ratios, the slope of this relationship decreased from the least decomposed POM pools (coarse POM) to the most decomposed POM pools (fine intra-aggregate POM). Moreover, C/N ratios of protected pools did not vary across N rates, suggesting little effect of N fertilizer on soil organic matter (SOM) after decomposition of POM. Comparing a N rate within 4% of agronomic optimum (208kg Nha(-1)yr(-1)) and an excessive N rate (269kg Nha(-1)yr(-1)), there were no differences between SOC amount, SOM C/N ratios, or microbial biomass and composition. These data suggest that excessive N fertilizer had little effect on SOM and they complement agronomic assessments of environmental N losses, that demonstrate N2O and NO3 emissions exponentially increase when agronomic optimum N is surpassed.
  • Authors:
    • Deng, J.
    • Zhou, Z.
    • Wang, K.
    • Liu, C.
    • Zheng, X.
    • Cui, F.
  • Source: Biogeosciences Discussions
  • Volume: 10
  • Year: 2014
  • Summary: Contemporary agriculture is shifting from a single-goal to a multi-goal strategy, which in turn requires choosing best management practice (BMP) based on an assessment of the biogeochemical effects of management alternatives. The bottleneck is the capacity of predicting the simultaneous effects of different management practice scenarios on multiple goals and choosing BMP among scenarios. The denitrification-decomposition (DNDC) model may provide an opportunity to solve this problem. We validated the DNDC model (version 95) using the observations of soil moisture and temperature, crop yields, aboveground biomass and fluxes of net ecosystem exchange of carbon dioxide, methane, nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) from a wheat-maize cropping site in northern China. The model performed well for these variables. Then we used this model to simulate the effects of management practices on the goal variables of crop yields, NO emission, nitrate leaching, NH3 volatilization and net emission of greenhouse gases in the ecosystem (NEGE). Results showed that no-till and straw-incorporated practices had beneficial effects on crop yields and NEGE. Use of nitrification inhibitors decreased nitrate leaching and N2O and NO emissions, but they significantly increased NH3 volatilization. Irrigation based on crop demand significantly increased crop yield and decreased nitrate leaching and NH3 volatilization. Crop yields were hardly decreased if nitrogen dose was reduced by 15% or irrigation water amount was reduced by 25 %. Two methods were used to identify BMP and resulted in the same BMP, which adopted the current crop cultivar, field operation schedules and full straw incorporation and applied nitrogen and irrigation water at 15 and 25% lower rates, respectively, than the current use. Our study indicates that the DNDC model can be used as a tool to assess biogeochemical effects of management alternatives and identify BMP.
  • Authors:
    • Balarezo Giarola, N.
    • Tormena, C.
    • Ball, B.
    • da Silva, A.
    • Locks Guimaraes, R.
  • Source: Scientia Agricola
  • Volume: 71
  • Issue: 2
  • Year: 2014
  • Summary: No-tillage in Brazil is an efficient agricultural system that improves crop productivity whilst controlling erosion caused to the soil by degradation. However, there is some concern regarding soil compaction. Our objective was to determine whether the function of soil structure in sustaining crop growth was dependent on row and interrow positions in long-term no-tillage. We took soil samples from a field in a commercial farm under long-term no-tillage since 1979 on a clayey Oxisol in Southern Brazil. We assessed soil physical quality using the revised Peerlkamp technique and measured bulk density, air-filled porosity and air permeability of intact soil cores. Samples were incubated to assess in vitro N2O and CO2 production. The soil physical and structural properties showed consistent differences between interrow and row positions, where the properties measured were more favorable. The revised Peerlkamp technique proved as efficient as quantitative parameters in discriminating treatment differences. Overall, soil physical conditions in the interrow were less favourable than in the row. Pore continuity did not vary as regards position. This may explain why row position did not influence in vitro N2O and CO2 production. Soil physical quality under no-tillage system is enhanced, at least in the short term, by superficial disturbances in the row as a result of the action of the coulters of the no-tillage seeder.
  • Authors:
    • Schmidt, J.
    • Bryant, R.
    • Han, K.
    • Dell, C.
  • Source: American Society of Agronomy
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: The use of enhanced efficiency N fertilizers can increase crop N utilization and lead to lower emissions of the greenhouse gas N2O. To determine the potential benefit of four enhanced efficiency fertilizers with rainfed corn (Zea mays L.) production in central Pennsylvania, N2O emissions and grain yield were monitored during a 4-yr field study and compared with untreated urea prills and urea-NH4NO3 (UAN). The tested enhanced efficiency products were ESN (polymer-coated urea), SuperU (urease and nitrification inhibitor treated urea), UAN treated with AgrotainPlus (urease and nitrification inhibitors), and PiNT (cation-stabilized amine-N). Additionally, 28-d laboratory incubations were conducted to verify the potential differences in N cycling rates among N sources. The laboratory incubations indicated that ESN, SuperU, and treated UAN all had the potential to delay accumulation of NO3 relative to untreated urea and UAN, but N cycling was similar with PiNT and the untreated fertilizers. Extended dry periods limited the denitrification potential and overall N2O emissions in the field, but spikes of N2O emission were seen within 1 mo after fertilizer application in each year. However, variation in emission rates was high within treatments, and no consistent differences among N sources were seen. Cumulative growing season N2O emissions and grain yield were similar for all N sources in each year of the study. Enhanced efficiency fertilizers do not appear to be an effective means to reduce N2O emission in a rainfed system, at least when rainfall is inconsistent.
  • Authors:
    • Egbemba, B.
    • Ezeaku, P.
  • Source: African Journal of Biotechnology
  • Volume: 13
  • Issue: 11
  • Year: 2014
  • Summary: The study is aimed at evaluating the effects of compost manure on the remediation of automobile oil waste polluted soils, and on the yield parameters (plant height, leave surface and dry matter weight) of maize ( Manoma spp.). Analyses of soil samples of contaminated and uncontaminated sites collected with core samplers at 10 cm depth and auger samplers at two depths (surface, 0-20 cm; subsurface, 20-40 cm) were examined for chemical and physical properties, including poly aromatic hydrocarbons. Polluted soils were biotreated for testing maize in a greenhouse. Soil physical and chemical properties decreased with depth and were significantly (P1) of heavy metals (for example; Zn, Cu, Mn) was high for maize cultivation. Paradigm approach emphasizing sustainable biological soil systems management is desired. Particularly, bioremediation of oil polluted soils using organic materials, and siting of mechanic villages several kilometers away from major land uses (residential houses, farm lands, and usable water bodies) are important for protecting the soil resources for agricultural purposes, and to ensuring environmental sanity and sustainability.
  • Authors:
    • Polprasert, C.
    • Tangtham, N.
    • Chidthaisong, A.
    • Jaiarree, S.
    • Sarobol, E.
    • Tyler, S.
  • Source: Land Degradation and Development
  • Volume: 25
  • Issue: 2
  • Year: 2014
  • Summary: The effects of compost application on soil carbon sequestration potential and carbon budget of a tropical sandy soil was studied. Greenhouse gas emissions from soil surface and agricultural inputs (fertiliser and fossil fuel uses) were evaluated. The origin of soil organic carbon was identified by using stable carbon isotope. The CO2, CH4 and N2O emissions from soil were estimated in hill evergreen forest (NF) plot as reference, and in the corn cultivation plots with compost application rate at 30 Mg ha(-1) y(-1) (LC), and at 50 Mg ha(-1) y(-1) (HC). The total C emissions from soil surface were 8 center dot 54, 10 center dot 14 and 9 center dot 86 Mg C ha(-1) y(-1) for NF, HC and LC soils, respectively. Total N2O emissions from HC and LC plots (2 center dot 56 and 3 center dot 47 kg N2O ha(-1) y(-1)) were significantly higher than from the NF plot (1 center dot 47 kg N2O ha(-1) y(-1)). Total CO2 emissions from fuel uses of fertiliser, irrigation and machinery were about 10 per cent of total CO2 emissions. For soil carbon storage, since 1983, it has been increased significantly (12 Mg ha(-1)) under the application of 50 Mg ha(-1) y(-1) of compost but not with 30 Mg ha(-1) y(-1). The net C budget when balancing out carbon inputs and outputs from soil for NF, HC and LC soils were +3 center dot 24, -2 center dot 50 and +2 center dot 07 Mg C ha(-1) y(-1), respectively. Stable isotope of carbon (delta C-13 value) indicates that most of the increased soil carbon is derived from the compost inputs and/or corn biomass. Copyright (c) 2011 John Wiley & Sons, Ltd.
  • Authors:
    • Dias, G.
    • Wagner-Riddle, C.
    • Jayasundara, S.
    • Kariyapperuma, K.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 1
  • Year: 2014
  • Summary: Analysis of the environmental impact of corn (Zea mays L.) uses, such as biofuels and bioproducts, requires cradle to farm-gate life-cycle analysis of energy use and net greenhouse gas (GHG) emissions associated with corn production. Previous analyses have been based on case studies. Here we present an analysis based on census data for Ontario at the county level that was performed for three scenarios: (1) corn cultivated only for grain; (2) corn cultivated for grain and 30% stover harvest; and (3) corn cultivated for grain and cob harvest. Energy intensity of corn grain at the county level varied from 1.75 to 2.17 GJ Mg-1 grain, with the largest proportions of energy being consumed for grain drying (33%), production and supply of nitrogen (N) fertilizer (30%) and diesel use for field work (17%). Overall GHG emission intensity of grain corn varied from 243 to 353 kg CO(2)eq Mg-1 grain, of which 72% were associated with N inputs [34% soil nitrous oxide (N2O) from synthetic fertilizer N (SFN), 13% from SFN production and 10% from applied manure N]. Energy intensity of corn stover and cobs was 0.96 and 0.36 GJ Mg-1 dry matter, respectively, with the largest proportion of energy associated with production and supply of replacement nutrients. Intensity of GHG emission was 79 and 31 kg CO2 eq Mg-1 dry matter for stover and for cobs, respectively. Counties with higher corn yields at lower N application rates and reduced tillage tended to produce corn with lower energy and GHG intensity per Mg grain.