• Authors:
    • Archer, D. W.
    • Lee, J.
  • Source: Scopus
  • Volume: 1
  • Year: 2014
  • Summary: An important driver for the adoption of renewable fuels is reduction in greenhouse gas (GHG) emissions, and the quantity of greenhouse gas reductions achieved is used in determining the fuel feedstocks and conversion pathways that can be used for fuels to meet the U.S. renewable fuels standard. Estimating GHG emissions from cropping system is an important component in quantifying GHG emissions through entire process from feed stock to final product use for oilseed based renewable fuels. Soil Organic Carbon (SOC) change is a key measure for calculating GHG emission from cropping systems because increase of SOC is regarded as C02 deposition from atmosphere to soil. Even though many researchers have simulated long term impacts of cropping system on SOC, the calibration and validation for C dynamic parameters using long-term soil profile data have been limited. The objective of this study is modeling long-term SOC change under impact of Brassica oil seed cropping systems with calibration and validation of soil C dynamics parameters in the EPIC model. We validated crop growth parameters from several areas of Northern Great Plains regions using field scale crop yield and management data at Mandan, ND. Soil C dynamics parameters (microbial decay rate coefficient) were calibrated and validated using soil profile data in 1983, 1991 and 2001 from long-term soil quality studies conducted at Mandan, ND since 1983. After calibration and validation, SOC and crop yields were modeled for each SSURGO soil map unit in Ward County, ND, one of pilot counties being evaluated for potential oilseed supply for hydrotreated renewable jet fuel production. The simulation was conducted under two rotation scenarios, canola-spring wheat-spring wheat and continuous spring wheat with no-tillage. The soil parameters from SSURGO were initialized by 100 year run with continuous spring wheat before imposing the two rotation scenario treatments. The results from 50-year simulation indicate that the canola cropping system is beneficial to store SOC compared to continuous spring wheat in all test map units. However, differences vary across soil map units.
  • Authors:
    • Kage, H.
    • Pacholski, A.
    • Ni, K.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: Ammonia emission from urea application negatively affects both environmental quality and human health, and so it is desirable to minimize nitrogen loss by ammonia volatilization and to improve nitrogen use efficiency. This field study aimed to assess the effects of recently introduced urease ( N-(2-nitrophenyl) phosphoric triamide, 2-NPT) and nitrification inhibitors (mixture of dicyandiamide and 1 H-1,2,4-triazol) on NH 3 emissions following urea application as compared to calcium ammonium nitrate (CAN) in Northern Germany. The measurements were carried out in winter wheat ( Triticum aestivum) in the years 2011-2013 covering in total 12 urea application dates. Urea was applied as unamended granulated urea, or combined with urease or nitrification inhibitor or with both inhibitors. Fertilizers were applied in multi-plot field trials with four replications and ammonia losses were measured simultaneously by a combination of a calibrated dynamic chamber and passive samplers. Application date strongly affected relative NH 3 loss (% of applied N) due to seasonal variation of soil moisture, temperature, and rainfall. Initial soil moisture showed a strong effect on NH 3 emission. Averaged over the three vegetation periods, relative NH 3 losses from unamended urea amounted to 8%, with mean emissions of 5%, 4%, and 17% for split N applications in March, April, and early June, respectively. Compared with treatment without urease inhibitor, the urease inhibitor addition reduced emissions by 26-83%, resulting in emissions similar to that from CAN. Analyzing the total data set, no significant effect of the nitrification inhibitor on NH 3 emission was observed while at specific applications significantly higher as well as lower emissions compared to unamended urea were detected. The results highlight that NH 3 emissions after field application of urea are highly variable under north German climate conditions and simple emission factors should be reevaluated. Urease inhibitor and appropriate application timing are effective measures to reduce NH 3 emission from field applied urea.
  • Authors:
    • Tambong, J.
    • Voroney, P.
    • Ondoua, B.
    • Nkoa, R.
  • Source: Sustainable Agriculture Research
  • Volume: 3
  • Issue: 4
  • Year: 2014
  • Summary: Knowledge on the interaction between plants and organic amendments is critical for the basic understanding of agroecosystems sustainability. Organic amendments are of great interest in agriculture by virtue of their ability to restore lost soil organic carbon in eroded or conventionally cultivated soils. The major objective of this study was to demonstrate and model the differential response of crop species to organic amendments. Despite the potential of such an interaction to improve crop production, it has never been formally demonstrated in a planned experiment. A two-year greenhouse experiment set as 3*3*5 factorial in a strip-split plot design was conducted. The effects of crop species, type of organic amendment, and application rates on grain yield of soybean, canola, and wheat were evaluated. To account for the asymmetry of the concave responses of soybean, mathematical transcendental models were fitted, for the first time, to yield data. The interaction between crop species and amended soils was highly significant. Soybean displayed concave transcendental yield responses whereas canola and wheat exhibited negative exponential responses, irrespective of the type of amendment. Turkey compost outperformed turkey litter and beef manure by 30% and 52%, respectively, with respect to soybean production; whereas turkey litter outperformed turkey compost and beef manure by 144% and 264%, respectively, with respect to canola and wheat production. It is concluded that in greenhouse settings and perhaps field conditions, growth and development of crop species can be enhanced by matching the specific characteristics of organic amendments to the specific nutrients demand of crop species.
  • Authors:
    • Raghuwansi, J.
    • Singh,R. C.
    • Kundu, S.
    • Rao, A. S.
    • Lenka, N. K.
    • Lenka, S.
    • Patidar, C. P.
  • Source: CURRENT SCIENCE
  • Volume: 107
  • Issue: 7
  • Year: 2014
  • Summary: Biomass burning is a major contributor to the atmospheric carbon budget and increases the concentration of many trace gases apart from the adverse effects on soil properties. However, in many parts of India, crop residue burning is a recurrent and widespread practice for disposal of the residues after harvest of the previous crop to facilitate sowing of the succeeding crop. The residue burning on a larger scale also leads to severe atmospheric pollution. Against this backdrop, the present work was conducted to study the effect of wheat ( Triticum aestivum) residue burning on soil properties and assess the potential greenhouse gas emission from burning of such residues on a regional scale. The study was taken up on farmers' field in Bhopal district, Madhya Pradesh, with two residue disposal methods, viz. residue burning and residue removal, for comparison with respect to their effect on soil properties and the greenhouse gas emission potential. No significant difference was observed between both methods in terms of soil organic carbon, inorganic carbon and available P content at 0-15 and 15-30 cm soil depths. Though residue burning showed favourable effect on available K content, there was reduction in the available N content in the 15-30 cm soil depth. Residue burning did not show significant effect on soil biological activity as estimated from fluorescence diacetate test. On the other hand, there was a significant adverse effect on soil structure and labile carbon content. Residue burning was estimated to result in the emission of 379 Gg C equivalent for India and 14 Gg C equivalent for MP.
  • Authors:
    • Muehling, K. H.
    • Kage, H.
    • Herrmann, A.
    • Wienforth, B.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: BIOENERGY RESEARCH
  • Volume: 7
  • Issue: 4
  • Year: 2014
  • Summary: There is a growing concern that greenhouse gas (GHG) emissions during agricultural energy crop production might negate GHG emission savings which was not intended when promoting the use of renewable energy. Nitrous oxide (N2O) is a major GHG, and in addition, it is the most powerful ozone-depleting compound that is emitted by human activity. The use of N fertilizers and animal manures is the main anthropogenic source of N2O emissions. In spite of their high relevance, we still have limited understanding of the complex underlying microbial processes that consume or produce N2O and their interactions with soil types, fertilizers (rate and types), plants, and other environmental variables. In a 2-year field experiment, we compared two important biogas crops in two different agro-ecological regions of northern Germany for their productivity and GHG emissions, using the closed-chamber technique and high time-resolution sampling. Silage maize, which is currently the most widespread crop grown for biogas fermentation purposes in Germany, was compared with an alternative bioenergy crop at each site. The three forms of nitrogen fertilizers/manures were given: calcium ammonium nitrate, cattle/pig slurry, and biogas residue. The greatest N2O flux activity occurred in the period of May-July in all crops and at both sites. Flux patterns indicated pronounced effects of soil moisture-soil mineral-N interactions which were also seen as causation of the higher N2O fluxes in the bioenergy crop maize compared to the other tested energy crops. However, the N2O emission per unit methane production (specific N2O emission) was clearly lower in soils planted with maize due to significantly higher methane hectare yield of maize. Our data suggest a linear relationship between increasing N input and increases in N2O emission in both years at site with sandy loam texture where highest N2O fluxes were measured. At sandy loam site, the percentage of applied N being emitted as N2O was 1.9 and 1.1 % in soils cropped with maize and 0.9 and 0.8 % in soils cropped with wheat during the investigation period 2007-2008 and 2008-2009, respectively. In contrast, at site with sandy soil texture, the percentage of applied N emitted as N2O was only 0.6 and 0.7 % in maize soils and 0.4 and 0.3 % in grassland during 2007-2008 and 2008-2009 period, respectively. Higher daily and annual N2O emissions at the sandy loam site were attributed to the finer soil texture and higher denitrification activity. The present study provides a very good basis for the assessment of direct emissions of greenhouse gases from relevant biogas crops in North-West Europe.
  • Authors:
    • Roisin, C.
    • Van Oost, K.
    • Trigalet, S.
    • van Wesemael, B.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 196
  • Year: 2014
  • Summary: Detecting soil organic carbon (SOC) gain or loss is challenging due to large uncertainties deriving from temporal and spatial variability of organic carbon concentrations, even at the field scale. In order to reduce these uncertainties, we used the organic carbon associated with clay and fine silt particles (fine fraction) rather than SOC in bulk soil for assessing decadal changes. This approach reduces the impact of the inherent variability of labile carbon on SOC estimates. We analysed archived soil samples taken in 1970 and recent ones taken in 2012 from an on-going long-term field trial in the Hesbaye region in Belgium. The experiment started in 1959 and contains three contrasting management practices (3*6 replicates): residue export (RE), farmyard manure (FYM) and residue restitution (RR). After 42 years, there are no significant differences in bulk soil organic carbon concentrations between treatments (RE=9.2 g C kg -1 soil; FYM=10.4 g C kg -1 soil; RR=10.1 g C kg -1 soil). In contrast, there are significant differences ( p<0.05) in stable carbon concentration (C associated to the fine fraction) between treatments over the same time period (RE=13.2 g C kg -1 clay and fine silt; FYM=16.6 g C kg -1 clay and fine silt; RR=15.4 g C kg -1 clay and fine silt). Moreover, we can be 99% confident that stable carbon in the fine fraction increased between 1970 and 2012 in FYM (+19%, p<0.01) and RR plots (+14%, p<0.01). There was a small, but significant, change of stable carbon in RE plots over the same period. In 1970, no differences in stable carbon concentration were detected between residue treatments. Labile carbon did not change significantly from 1970 to 2012 but its variability increased for all plots except for the RE treatment. We used the Rothamsted carbon model (RothC-26.3) to describe SOC changes under the different residue treatments. For bulk soil, observed trends in FYM and RR SOC concentrations are in line with the ones predicted. Modeled SOC changes from 1962 to 2012 are -14% (RE) and +10% (FYM). We also used RothC-26.3 to understand the evolution of the sensitive and slow fractions over time. On the one hand, we found that RothC was not capable to simulate the range of observed SOC concentrations inter-annual variability. On the other hand, the increase of the RothC pool with slow decomposition (HUM) was similar to the trend in the carbon associated with the fine fraction observed in the FYM and RR plots. This finding highlights that residue management can increase the storage of C in more stable fractions in agricultural soils, even when no changes are detected in bulk soil C.
  • Authors:
    • Li, S.
    • You, D. H.
    • Lu, X. C.
    • Liu, T.
    • Tian, X. H.
    • Wang, S. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Soil water, organic C, and N management practices exert strong influences on winter wheat ( Triticum aestivum L.) yield and soil properties under dryland farming conditions. Here, a 9-yr field experiment was conducted in northwestern China using treatments that included nine factorial combinations of three cultivation practices, conventional cultivation (CC), straw mulching (SM), and supplementary irrigation (SI), and three N application rates (0, 120, and 240 kg N ha -1). Relative yield gradually declined under CC and SM with N, yet remained steady under SI. Without N, yield decreased by 50 to 60%. Soil organic carbon (SOC), labile organic carbon (LOC), total nitrogen (TN), and available potassium (AK) in the 0 to 20 cm (upper) soil layer were significantly increased by SM but were unaffected by SI treatments. After wheat harvest, N application increased SOC, LOC, and TN in the upper soil layer by an average of 4.81, 20.70, and 7.61%, respectively, and decreased AK by 6.12%. The cultivation practice and N fertilizer effects on soil properties were more pronounced in upper than deeper layer (20-40 cm). At soil depths of 0 to 100 cm, nitrate accumulation under N 240 exceeded 69.27% of the critical environmental risk value. Thus, SI+N 120 achieved a high and stable wheat yield, and SM+N 120 increased soil fertility. However, the two combinations applied over 9 yr did not meet both high soil fertility and high productivity needs. Additionally, cultivation practices with high N fertilizer are not sustainable soil management techniques in dryland regions.
  • Authors:
    • Wuest, S. B.
    • Williams, J. D.
    • Long, D. S.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 6
  • Year: 2014
  • Summary: The winter wheat (Triticum aestivum L.)/summer fallow rotation typically practiced in the intermediate precipitation zone (300 to 450 mm [12 to 18 in]) of the inland Pacific Northwest has proven to be economically stable for producers in this region. However, multiple tillage operations are used to control weeds and retain seed-zone soil moisture, which disturbs the soil and makes it prone to substantial erosion. Alternatives to this conventional disturbance tillage (DT) system include either no-tillage (NT) or minimum tillage (MT) in combination with increasing cropping intensity. The objective of this study was to compare runoff, soil erosion, crop residue, and yield productivity resulting from NT, and DT, or MT. Small collectors and flumes were used to quantify runoff and soil erosion from small drainages and slopes in three different experiments near Pendleton, Oregon. The first experiment included two neighboring drainages:one farmed using DT with a two-year crop rotation over eight years (2001 to 2008) and the other NT with a four-year crop rotation (2001 to 2008). The second experiment comprised a hillslope planted to different crops using NT over eight years (1998 to 2005) and MT over three years (2006 to 2008). The third experiment was situated in a shallow draw in which NT and MT with a four-year (2004 to 2008) crop rotation was compared. Runoff measured in flumes was substantially influenced by tillage method in the order of DT > NT in a ratio of 10:1 at the first site. At the second site, NT produced no runoff compared to 1.6 mm y(-1) (0.06 in yr(-1)) from MT. Soil erosion was found to be DT > NT in a ratio of 5:1 at the first site and 2:1 for the second site. For small collectors the differences were significant:runoff was DT > NT in a ratio of 47:1 for the first site, and MT > NT in a ratio of 2:1 for the third site. Winter wheat yields did not differ significantly among NT, DT, and MT. Broader acceptance of NT cropping systems in the intermediate precipitation zone of this region would substantially decrease soil losses from farm fields and improve downstream water quality.
  • Authors:
    • Malhi, S. S.
    • Zentner, R.
    • Worth, D. E.
    • Desjardins, R. L.
    • Smith, W. N.
    • Grant, B. B.
    • Goglio, P.
  • Source: SCIENCE OF THE TOTAL ENVIRONMENT
  • Volume: 490
  • Year: 2014
  • Summary: Estimating the greenhouse gas (GHG) emissions from agricultural systems is important in order to assess the impact of agriculture on climate change. In this study experimental data supplemented with results from a biophysical model (DNDC) were combined with life cycle assessment (LCA) to investigate the impact of management strategies on global warming potential of long-term cropping systems at two locations (Breton and Ellerslie) in Alberta, Canada. The aim was to estimate the difference in global warming potential (GWP) of cropping systems due to N fertilizer reduction and residue removal. Reducing the nitrogen fertilizer rate from 75 to 50 kg N ha(-1) decreased on average the emissions of N2O by 39%, NO by 59% and ammonia volatilisation by 57%. No clear trend for soil CO2 emissions was determined among cropping systems. When evaluated on a per hectare basis, cropping systems with residue removal required 6% more energy and had a little change in GWP. Conversely, when evaluated on the basis of gigajoules of harvestable biomass, residue removal resulted in 28% less energy requirement and 33% lower GWP. Reducing nitrogen fertilizer rate resulted in 18% less GWP on average for both functional units at Breton and 39% less GWP at Ellerslie. Nitrous oxide emissions contributed on average 67% to the overall GWP per ha. This study demonstrated that small changes in N fertilizer have a minimal impact on the productivity of the cropping systems but can still have a substantial environmental impact. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.
  • Authors:
    • Al-Mansour, F.
    • Jejcic, V.
  • Source: Proceedings of the 42nd International Symposium on Agricultural Engineering, Actual Tasks on Agricultural Engineering, Opatija, Croatia, 25-28 February, 2014
  • Year: 2014
  • Summary: An analysis of the carbon footprint of conventional, integrated and organic crop production, and three sizes of farms was made. Conventional tillage and direct seeding were used in mentioned production systems. For the analysis of the carbon footprint, CO 2 emissions from fossil fuel (direct energy) consumed in the process of production of corn (for silage and grain), wheat, rapeseed, and sunflower were used. In addition to emissions from fossil fuels used in the production of mentioned crops, greenhouse gas emissions resulting from the use of organic and mineral fertilizers in the production and converted to CO 2 equivalents were also used. In the case of conventional production mineral fertilizers were used, in integrated production combination of mineral fertilizers and organic fertilizers and in organic production only organic fertilizer was used. The sum of emissions arising from fossil fuel use and emissions from fertilizers used in the cultivation process, make final emission from crop production. It was estimated that the emissions of CO 2/t of yields in conventional and integrated production are about the same. In organic production emissions of CO 2/t of yields are higher in comparison with emissions CO 2/t of yields in conventional and integrated farming. CO 2 emissions in conventional and organic production (CO 2/t of yield) are in the following proportions: corn for grain 1:1.34, corn for silage 1:1.52, wheat 1:1.53, rapeseed 1:1.47 and sunflower 1:1.2 (the higher is the number of organic production).