• Authors:
    • Gerik, T. J.
    • Williams, J. R.
    • Blumenthal, J. M.
    • Potter, S. R.
    • Kemanian, A. R.
    • Meki, M. N.
  • Source: Agricultural Systems
  • Volume: 117
  • Year: 2013
  • Summary: There is an increased demand on agricultural systems in the United States and the world to provide food, fiber, and feedstock for the emerging bioenergy industry. The agricultural intensification that this requires could have positive and negative feedbacks in productivity and the environment. In this paper we used the simulation model EPIC to evaluate the impact of alternative tillage and management systems on grain sorghum (Sorghum bicolor L. Moench) production in central and south Texas and to provide long-term insights into the sustainability of the proposed systems as avenues to increase agricultural output. Three tillage systems were tested: conventional (CT), reduced (RT), and no-tillage (NT). These tillage systems were tested on irrigated and rainfed conditions, and in soils with varying levels of structural erosion control practices (no practice, contour tillage, and contours + terraces). Grain yield differed only slightly across the three tillage systems with an average grain yield of 5.7 Mg ha(-1). Over the course of 100-year simulations, NT and RT systems had higher soil organic carbon (SOC) storage (100 and 91 Mg ha(-1), respectively) than CT (85 Mg ha(-1)), with most of the difference originating in the first 25 years of the simulations. As a result, NT and RT systems showed lower net global warming potentials (GWPs) (0.20 and 0.50 Mg C ha(-1) year(-1)) than CT (0.60 Mg C ha(-1) year(-1)). Irrigated systems had 26% higher grain yields than rainfed systems; yet the high energy needed to pump irrigation water (0.10 Mg C ha(-1) year(-1)) resulted in a higher net GWP for irrigated systems (0.50 vs. 0.40 Mg C ha(-1) year(-1)). Contours and contours + terraces had minimal impact on grain yields, SOC storage and GWP. No-till was the single technology with the largest positive impact on GWP and preservation or enhancement of SOC. Overall, the impact of individual tillage cropping systems on GWP seems to be decoupled from the productivity of a given location as determined by weather or soil type. When expressed per unit of output, high yield locations have a much lower GWP than low yield locations and would be therefore prime targets for production intensification. Published by Elsevier Ltd.
  • Authors:
    • Xie, D. T.
    • Shi, S.
    • Liu, Y. Y.
    • Li, J. Q.
    • Ni, J. P.
    • Huang, A. Y.
    • Mu, Z. J.
    • Hatano, R.
  • Source: Journal of Soil Science and Plant Nutrition
  • Volume: 13
  • Issue: 3
  • Year: 2013
  • Summary: Vegetable fields in China are characterized with intensive fertilization and cultivation, and their net effect on the global warming deserves attention. Greenhouse gas fluxes were thus measured, using a static closed chamber method, over approximately 18 months in two typical subtropical vegetable fields with different soil types and contrasting soil properties. Five consecutive crops were planted in one field and four in the other. Intensive fertilization consistently stimulated soil N2O emission, while imposed complicated impact on soil respiration with CO2 emission enhanced in one field and suppressed in the other field. The fertilizer-induced N2O emission factors (EFs) varied with individual crop phases and averaged 1.4 to 3.1% across the whole sampling period for different fields. The interaction of soil temperature and moisture could explain about 58% of the seasonal variation in the EFs. All the soils under different vegetable cropping systems were net sources of atmospheric radiative forcing and the net global warming potential over the entire study period ranged from 1,786 to 3,569 g CO2 equivalence m(-2) for fertilized soils with net CO2 emission contributing 53 to 67% and N2O emission occupying the remaining 33 to 47%.
  • Authors:
    • Teague, T. G.
    • Niederman, Z.
    • Danforth, D. M.
    • Nalley, L. L.
  • Source: Journal of Cotton Science
  • Volume: 17
  • Issue: 2
  • Year: 2013
  • Summary: Greenhouse gas (GHG) emissions are a growing concern for agricultural producers given increased pressure from government, consumers and retail purchasers. This study addresses the changes in greenhouse gas emissions in cotton over time (using years 1997, 2005 and 2008) due to changing production methods including tillage and seed technology. Time series data in this study comes from a single farm in Arkansas with detailed records of seed used, all inputs used (e.g. fertilizers, agrochemicals, irrigation), as well as machinery and tillage type for each of over 121 fields over 11 growing seasons. Results indicate yields increased dramatically (68%) over that time, due primarily to seed technology. At the same time, agrochemical use and fuel use decreased in 2008, primarily due to Bollgard II Roundup Ready Flex seed technology and the resulting reduced tillage. Reduced inputs can result in lower costs for producers, as well as reduced greenhouse gas emissions. Increasing yields with reduction in input use reduces the overall greenhouse gas emissions per pound of cotton produced, resulting in benefits to producers, consumers who demand such traits, and the environment. However, due to the proliferation of glyphosate-resistant pigweed ( Amaranthus palmeri), the decreases in greenhouse gas emissions per pound of cotton that were observed over the past decade may be reversed.
  • Authors:
    • Higarashi, M. M.
    • Oliveira, P. A. V. de
    • Denega, G. L.
    • Bayer, C.
    • Silveira Nicoloso, R. da
    • Correa, J. C.
    • Santos Lopes, L. dos
  • Source: Ciencia Rural
  • Volume: 43
  • Issue: 2
  • Year: 2013
  • Summary: Assessments of soil carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) emissions are critical for determination of the agricultural practices' potential to mitigate global warming. This study evaluated the photoacoustic spectroscopy (PAS) for the assessment of soil greenhouse gases (GHG) fluxes in comparison to the standard gas chromatography (GC) method. Two long-term experiments with different tillage and cropping systems over a Paleudult were evaluated using static chambers. PAS measurements of CO 2 and N 2O concentrations showed good relationship and linearity (R 2=0.98 and 0.94, respectively) with GC results. However, CH 4 measurements were significantly affected by air sample moisture which interfered on CH 4 detection by PAS. Overestimation of CO 2 and N 2O concentrations in air samples determined by PAS (14.6 and 18.7%, respectively) were also related to sampling moisture. CO 2 and N 2O fluxes showed good agreement between methods (R 2=0.96 and 0.95, respectively), though PAS overestimated fluxes by 18.6 and 13.6% in relation to GC results, respectively. PAS showed good sensitivity and was able to detect CO 2 and N 2O fluxes as low as 332 mg CO 2 m -2 h -1 and 21g N 2O m -2 h -1. PAS analyzer should be detailed calibrated to reduce humidity interference on CO 2, CH 4 and N 2O concentrations measurements avoiding overestimation or erroneous determination of soil GHG fluxes.
  • Authors:
    • Pellegrino Cerri,Carlos Eduardo
    • Galdos,Marcelo Valadares
    • Nunes Carvalho,Joao Luis
    • Feigl,Brigitte Josefine
    • Cerri,Carlos Clemente
  • Source: Scientia Agricola
  • Volume: 70
  • Issue: 5
  • Year: 2013
  • Summary: Strategies to mitigate climate change through the use of biofuels (such as ethanol) are associated not only to the increase in the amount of C stored in soils but also to the reduction of GHG emissions to the atmosphere. This report mainly aimed to propose appropriate methodologies for the determinations of soil organic carbon stocks and greenhouse gas fluxes in agricultural phase of the sugarcane production. Therefore, the text is a piece of contribution that may help to obtain data not only on soil carbon stocks but also on greenhouse gas emissions in order to provide an accurate life cycle assessment for the ethanol. Given that the greenhouse gas value is the primary measure of biofuel product quality, biorefiners that can show a higher offset of their product will have an advantage in the market place.
  • Authors:
    • Xu, J.
    • Ostwald, M.
    • Moberg, J.
    • Persson, M.
  • Source: Journal of Environmental Management
  • Volume: 126
  • Year: 2013
  • Summary: The Grain for Green Programme (GGP) was launched in China in 1999 to control erosion and increase vegetation cover. Budgeted at USD 40 billion, GGP has converted over 20 million hectares of cropland and barren land into primarily tree-based plantations. Although GGP includes energy forests, only a negligible part (0.6%) is planted as such, most of the land (78%) being converted for protection. Future use of these plantations is unclear and an energy substitution hypothesis is valid. We estimate the overall carbon sequestration via GGP using official statistics and three approaches, based on i) net primary production, ii) IPCC's greenhouse gas inventory guidelines, and iii) mean annual increment. We highlight uncertainties associated with GGP and the estimates. Results indicate that crop- and barren-land conversion sequestered 222-468 Mt of carbon over GGP's first ten years, the IPCC approach yielding the highest estimate and the other two approaches yielding similar but lower estimates (approximately 250 Mt of carbon). The carbon stock in these plantation systems yields a mean of 12.3 t of carbon per hectare. Assessment uncertainties concern the use of growth curves not designed for particular species and locations, actual plantation survival rates, and discrepancies in GGP figures (e.g., area, type, and survival rate) at different authority levels (from national to local). The carbon sequestered in above- and below-ground biomass from GGP represents 14% (based on the median of the three approaches) of China's yearly (2009) carbon dioxide emissions from fossil fuel use and cement production.
  • Authors:
    • Moraes, O. L. L. de
    • Fontana, D. C.
    • Rodrigues, C. P.
    • Roberti, D. R.
  • Source: Revista Brasileira de Meteorologia
  • Volume: 28
  • Issue: 1
  • Year: 2013
  • Summary: The increasing on the greenhouse gases (GHG) emissions is today one of the main environmental problems, which can significantly affect human activities and land ecosystems. One of the main GHG is CO 2, which has been emitted indiscriminately due to the current lifestyle, as well as the intensification of agricultural activities. In this context, the objective of this investigation was to study the relationship between the spectral behavior of soybean during the crop cycle, using NDVI (Normalized Difference Vegetation Index), and the CO 2 fluxes, calculated by the eddy covariance method, generating information and methodology to investigate the carbon exchange in a soybean crop area in the State of Rio Grande do Sul, during the 2008/2009 soybean crop. For this, Landsat images 5 (TM), the phenological information and collected data from micrometeorological station throughout the development cycle of soybean were used. The results showed that the temporal pattern of CO 2 flux during the day was cyclical, showing negative values (capture) during daytime and positive values (liberation) at night. The global solar radiation determines the magnitude of the trapping of CO 2 by soybean, but the flow is modulated by the phenological stage of the crop. The photosynthetic activity of soybean plants is higher during the vegetative stage, coinciding to the higher incidence of solar radiation and the greater photosynthetic apparatus. The NDVI, obtained from Landsat images, is an indicator of the evolution of soybean biomass during the cycle. NDVI and negative CO 2 flow (capture) are correlated during the day. Therefore, remote sensing techniques show potentiality in generating of useful information on CO 2 exchange between the surface and atmosphere.
  • Authors:
    • Dias, C.
    • La Scala, N.
    • Cerri, C.
    • Silva-Olaya, A.
    • Cerri, C.
  • Source: Environmental Research Letters
  • Volume: 8
  • Issue: 1
  • Year: 2013
  • Summary: Soil tillage and other methods of soil management may influence CO2 emissions because they accelerate the mineralization of organic carbon in the soil. This study aimed to quantify the CO2 emissions under conventional tillage (CT), minimum tillage (MT) and reduced tillage (RT) during the renovation of sugarcane fields in southern Brazil. The experiment was performed on an Oxisol in the sugarcane-planting area with mechanical harvesting. An undisturbed or no-till (NT) plot was left as a control treatment. The CO2 emissions results indicated a significant interaction (p < 0.001) between tillage method and time after tillage. By quantifying the accumulated emissions over the 44 days after soil tillage, we observed that tillage-induced emissions were higher after the CT system than the RT and MT systems, reaching 350.09 g m(-2) of CO2 in CT, and 51.7 and 5.5 g m(-2) of CO2 in RT and MT respectively. The amount of C lost in the form of CO2 due to soil tillage practices was significant and comparable to the estimated value of potential annual C accumulation resulting from changes in the harvesting system in Brazil from burning of plant residues to the adoption of green cane harvesting. The CO2 emissions in the CT system could respond to a loss of 80% of the potential soil C accumulated over one year as result of the adoption of mechanized sugarcane harvesting. Meanwhile, soil tillage during the renewal of the sugar plantation using RT and MT methods would result in low impact, with losses of 12% and 2% of the C that could potentially be accumulated during a one year period.
  • Authors:
    • Inubushi, K.
    • Iwasa, H.
    • Dubey, S.
    • Singla, A.
  • Source: Biology and Fertility of Soils
  • Volume: 49
  • Issue: 7
  • Year: 2013
  • Summary: Biogas production generates digested slurry as a by-product. It can be used as fertilizer especially after its conversion into digested liquid. A microcosm-based study was conducted in order to compare the effects of single application of digested liquid or chemical fertilizer on N2O flux and crop yield of komatsuna vegetable. Analysis revealed that digested liquid-treated soils released almost equal cumulative N2O (0.43 g N m(-2)) compared to chemical fertilizer (0.39 g N m(-2)). The uncropped soils treated with the digested liquid and chemical fertilizer released more N2O compared to corresponding cropped soils. The N2O emission factor and soil mineral N contents were similar for the digested liquid and chemical fertilizer-treated soils. Plant biomass in the first crop after digested liquid application was significantly higher (5.59 g plant(-1)) than that after applied chemical fertilizer (4.78 g plant(-1)); but there was no significant difference for the second crop. Nitrogen agronomic efficiency was improved by the digested liquid compared to chemical fertilizer. This study indicates that cumulative N2O flux was similar after application of the digested liquid and chemical fertilizer, while the overall yield from both croppings was increased in the digested liquid-treated soil compared to chemical fertilizer-treated soil.
  • Authors:
    • Breedveld, G. D.
    • Martinsen, V.
    • Field, J. L.
    • Sparrevik, M.
    • Cornelissen, G.
  • Source: Environmental Science and Technology
  • Volume: 47
  • Issue: 3
  • Year: 2013
  • Summary: Biochar amendment to soil is a potential technology for carbon storage and climate change mitigation. It may, in addition, be a valuable soil fertility enhancer for agricultural purposes in sandy and/or weathered soils. A life cycle assessment including ecological, health and resource impacts has been conducted for field sites in Zambia to evaluate the overall impacts of biochar for agricultural use. The life cycle impacts from conservation farming using cultivation growth basins and precision fertilization with and without biochar addition were in the present study compared to conventional agricultural methods. Three different biochar production methods were evaluated: traditional earth-mound kilns, improved retort kilns, and micro top-lit updraft (TLUD) gasifier stoves. The results confirm that the use of biochar in conservation farming is beneficial for climate change mitigation purposes. However, when including health impacts from particle emissions originating from biochar production, conservation farming plus biochar from earth-mound kilns generally results in a larger negative effect over the whole life cycle than conservation farming without biochar addition. The use of cleaner technologies such as retort kilns or TLUDs can overcome this problem, mainly because fewer particles and less volatile organic compounds, methane and carbon monoxide are emitted. These results emphasize the need for a holistic view on biochar use in agricultural systems. Of special importance is the biochar production technique which has to be evaluated from both environmental/climate, health and social perspectives.