• Authors:
    • Lenka, N. K.
    • Lal, R.
  • Source: Soil and Tillage Research
  • Volume: 126
  • Year: 2013
  • Summary: Mulching effect on carbon (C) sequestration depends on soil properties, mulch material, and the rate and duration of application. Thus, rate of soil C sequestration was assessed on a 15 year field study involving three levels of wheat straw at 0 (M-o), 8 (M-8) and 16 (M-16) Mg ha(-1) yr(-1), at two levels (244 kg N ha(-1) yr(-1), F-1 and without, F-0) of supplemental N. Soil C concentration was assessed in relation to aggregation and occlusion in aggregates of a silt loam Alfisol under a no-till (NT) and crop-free system in central Ohio. In comparison to control, soil organic carbon (SOC) concentration in the 0-10 cm depth of bulk soil increased by 32% and 90% with M-8 and M-16 treatments with a corresponding increase in the SOC stock by 21-25% and 50-60%, respectively. With increase in rate of residue mulch, proportion of water stable aggregates (small macroaggregates, >250 mu m size) increased by 1.4-1.8 times and of microaggregates (53-250 mu m) by 1.4 times. Fertilizer N significantly increased the SOC concentration of small macroaggregates under M-16 treatments only. Ultra-sonication showed that 12-20% of SOC occluded in the inter-microaggregate space of small macroaggergates, was a function of both mulch and fertilizer rates. Significantly higher and positive correlation of greenhouse gases (GHGs), CO2, CH4 and N2O flux was observed with C and N concentrations of small macroaggregates and also of the occluded fraction of small macroaggregates. The higher correlation coefficient indicated the latter to be prone to microbial attack. On the contrary, non-significant relationship with C and N concentrations of microaggregates indicate a possible protection of microaggregate C. The diurnal fluxes of CO2, CH4 and N2O were the lowest under bare soil and the highest under high mulch rate with added N, with values ranging from 1.51 to 2.31 g m(-2) d(-1), -2.79 to 3.15 mg m(-2) d(-1) and 0.46 to 1.02 mg m(-2) d(-1), respectively. Mulch rate affected the GHGs flux more than did the fertilizer rates. The net global warming potential (GWP) was higher for high mulch (M-16) than low mulch (M-8) rates, with values ranging from 0.46 to 0.57 Mg CO2 equivalent - C ha(-1) yr(-1) (M-8) and 1.98 to 3.05 Mg CO2 equivalent - C ha(-1) yr(-1) (M-16). In general, mulch rate determined the effect of fertilizers. The study indicated that overlong-term, a mulch rate between 8 and 16 Mg ha(-1) yr(-1) may be optimal for Alfisols in Central Ohio. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Silva, P.
    • Pino, V.
    • Fuentes, J.-P.
    • Martinez, E.
    • Acevedo, E.
  • Source: Soil and Tillage Research
  • Volume: 126
  • Year: 2013
  • Summary: Soil management practices may change the soil properties. The magnitude of the change varies according to the soil property, the climate, and the type and time of implementation of a particular management system. The aim of this study was to evaluate the effects of no-tillage (NT) on the chemical and biological properties of an Entic Haploxeroll in Central Chile. Soil organic carbon (SOC), microbial biomass and associated indicators q(CO2), q(Mic), q(Min), available N, P and K, pH, electrical conductivity (EC), and crop yield were determined in a field experiment having a wheat (Triticum turgidum L)-maize (Zea mays L.) crop rotation. The change in soil chemical properties was further evaluated using a greenhouse bioassay in which ryegrass (Lolium perenne L) was grown in soil samples extracted at 0-2,2-5, and 5-15 cm depth. After nine years SOC in the NT treatment was 29.7 Mg ha(-1) compared to 24.8 Mg ha(-1) of CT, resulting in 4.98 Mg ha(-1) C gain. The NT therefore resulted in an average annual sequestration of 0.55 Mg C ha(-1) yr(-1) in the upper 15 cm soil. The soil organic C stored under NT was mainly accumulated in the top 2-cm of soil. The biological indicators showed a greater biological soil quality under NT than under CT. Soil organic C was positively associated with available N, P. and K, but negatively with soil pH. The iyegrass bioassay yielded higher biomass in NT than CT. An improvement in the soil chemical quality of the NT soil was considered to be the main reason for this result. The maize yield under NT had the tendency to improve in time as compared to CT. Wheat, however, had lower yield under NT. It was concluded that NT increased C sequestration and SOC improving the chemical and biological properties of this soil. (C) 2012 Elsevier B.V. All rights reserved.
  • 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:
    • Olson, K. R.
  • Source: Geoderma
  • Volume: 195
  • Issue: March
  • Year: 2013
  • Summary: The atmospheric levels of carbon dioxide (CO2) have been due largely to the burning of fossil fuels, deforestation, cultivation of the grasslands, drainage of the land, and land use changes. This has led to increase in greenhouse gases, created concerns about the potential for long-term climate change and interest in developing methods to sequester some of this atmospheric carbon. In agricultural land areas no-tillage (NT) systems have been proposed, to replace moldboard plow and chisel systems as a way to sequester soil organic carbon (SOC). Numerous estimates have been published of soil organic carbon (SOC) sequestration total and rates as a result of a switch to NT systems. Other researchers have proposed the use of cover crops, synthetic fertilizers, organic fertilizer, manure, liming, agricultural systems and management, agroforestry, forages, compost, crop rotations, and reduced row crop use as ways to sequester SOC. For SOC sequestration to occur as a result of a treatment applied to a land unit, all of the SOC sequestered must have come from atmosphere and be transferred into the soil humus through the unit plants, plant residues and other organic solids. The amount of SOC present in the soil humus at the end of the study has to be greater than the pre-treatment SOC levels in the same land unit and there needs to be a net depletion of atmospheric CO2 as a result. The objectives of this paper are to: (I) determine long-term study SOC levels and trends in agricultural lands, (2) application of the SOC sequestration concept to a specific site, (3) identify appropriate experimental designs for plot area use in determining SOC sequestration, (4) develop a procedure, such as pre-treatment measurements of SOC levels in the plots before treatments are applied, to verify SOC sequestration at a site (5) equivalent soil mass sampling method, (6) compare laboratory methods for quantifying SOC content, and (7) account for the loading of C rich amendments. To unequivocally demonstrate SOC sequestration at a specific site has occurred, a temporal increase must be documented relative to pre-treatment SOC level and linked to a net depletion of atmospheric CO2. (c) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Sainju, U. M.
  • Source: Agronomy journal
  • Volume: 105
  • Issue: 5
  • Year: 2013
  • Summary: Management practices can reduce N losses through N leaching and N2O emissions (a greenhouse gas) by increasing soil N storage. The effects of tillage, cropping sequence, and N fertilization rate were studied on N contents in dryland crop biomass, surface residue, and soil at the 0- to 120-cm depth, and estimated N balance from 2006 to 2011 in eastern Montana. Treatments were no-till continuous malt barley (Hordeum vulgaris L.) (NTCB), no-till malt barley-pea (Pisum sativum L.) (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F), each with 0 to 120 kg N ha(-1). Biomass and surface residue N increased with increased N rate and were greater in NTB-P or NTCB than CTB-F and NTB-F in all years, except in 2006 and 2011. Soil total nitrogen (STN) at 0 to 60 cm decreased from 2006 to 2011 at 254 kg N ha(-1) yr(-1), regardless of treatments. At most depths, soil NH4-N content varied, but NO3-N content was greater in CTB-F than other cropping sequences. Estimated N balance was greater in NTB-P with 40 kg N ha(-1) than other treatments. No-till continuous cropping increased biomass and surface residue N, but conventional till crop-fallow increased soil available N. Because of increased soil N storage and reduced N requirement to malt barley, NTB-P with 40 kg N ha(-1) may reduce N loss due to leaching, volatilization, and denitrification compared to other treatments.
  • Authors:
    • Rieradevall, J.
    • Ignacio Montero, J.
    • Oliver-Sola, J.
    • Ceron-Palma, I.
    • Sanye-Mengual, E.
  • Source: Journal of the science of food and agriculture
  • Volume: 93
  • Issue: 1
  • Year: 2013
  • Summary: BACKGROUND: As urban populations increase so does the amount of food transported to cities worldwide, and innovative agro-urban systems are being developed to integrate agricultural production into buildings; for example, by using roof top greenhouses (RTGs). This paper aims to quantify and compare, through a life cycle assessment, the environmental impact of the current linear supply system with a RTG system by using a case study for the production of tomatoes. RESULTS: The main results indicate that a change from the current linear system to the RTG system could result in a reduction, per kilogram of tomatoes (the functional unit), in the range of 44.4-75.5% for the different impact categories analysed, and savings of up to 73.5% in energy requirements. These savings are associated with re-utilisation of packaging systems (55.4-85.2%), minimisation of transport requirements (7.6-15.6%) and reduction of the loss of product during transportation and retail stages (7.3-37%). CONCLUSIONS: The RTG may become a strategic factor in the design of low-carbon cities in Mediterranean areas. Short-term implementation in the city of Barcelona could result in savings of 66.1 tonnes of CO2 eq. ha(-1) when considering the global warming potential, and of 71.03 t ha(-1) when considering that the transformation from woodland to agricultural land is avoided. (C) 2012 Society of Chemical Industry
  • Authors:
    • Rimal, B.
    • Lal, R.
    • Shrestha, R.
  • Source: Geoderma
  • Volume: 197
  • Year: 2013
  • Summary: The addition of organic amendments is essential for sustainable soil fertility management and crop production, but can also increase greenhouse gas (GHG) emissions. Thus, understanding the impacts of organic soil amendments on gaseous emissions is pertinent to minimizing agricultural impacts on the net emissions of GHGs. A long-term field experiment was conducted to assess the impacts of continuous application of organic amendments (i.e. compost and farmyard manure) and cover crop [mixture of rye (Secale cereal), red fescue (Festuca rubra), and blue grass (Poa pratensis L)] on selected soil properties, apparent carbon (C) budget (calculated from the difference of sum of all sources of C inputs and outputs), gaseous flux (i.e. carbon dioxide, CO2, and methane, CH4), and relationship with weather parameters under no-till (NT) corn (Zea mays L) cultivation in an Alfisol of central Ohio, USA. Soil properties and gaseous fluxes were measured continuously for 2 years. Ten years of continuous application of soil amendments increased soil pH and electrical conductivity, enhanced soil C pool, and decreased bulk density especially in 0-5 cm depth than that with cover crop and control plots. Two years average, cattle manure, compost, fallow, and cover crop emitted 14.1, 10.2, 7.5, and 7.2 Mg CO2-C ha(-1) yr(-1), respectively. Methane emission was 10.7 kg CH4-C ha(-1) yr(-1) from cattle manure and 4.0 kg CH4-C ha(-1) yr(-1) from compost However, fallow consumed 3.3 and cover crop 5.0 kg CH4-C ha(-1) yr(-1). These data suggest that long-term application of compost in NT corn decreased emissions of CO2 by 38% and of CH4 by 167% compared to application of manuring. In general, soil temperature, air temperature, and precipitation were positively correlated with CO2 emissions. Estimation of C budget indicated that amended soil under NT is a C-sink while a non-amended system is a C-source. The application of composted soil amendments in NT corn enhances soil quality and reduces net GHG emissions. Published by Elsevier B.V.
  • Authors:
    • Paustian, K.
    • Ngugi, M. K.
    • Suddick, E. C.
    • Six, J.
  • Source: California Agriculture
  • Volume: 67
  • Issue: 3
  • Year: 2013
  • Summary: California growers could reap financial benefits from the low-carbon economy and cap-and-trade system envisioned by the state's AB 32 law, which seeks to lower greenhouse gas emissions statewide. Growers could gain carbon credits by reducing greenhouse gas emissions and sequestering carbon through reduced tillage and increased biomass residue incorporation. First, however, baseline stocks of soil carbon need to be assessed for various cropping systems and management practices. We designed and set up a pilot soil carbon and land-use monitoring network at several perennial cropping systems in Northern California. We compared soil carbon content in two vineyards and two orchards (walnut and almond), looking at conventional and conservation management practices, as well as in native grassland and oak woodland. We then calculated baseline estimates of the total carbon in almond, wine grape and walnut acreages statewide. The organic walnut orchard had the highest total soil carbon, and no-till vineyards had 27% more carbon in the surface soil than tilled vineyards. We estimated wine grape vineyards are storing significantly more soil carbon per acre than almond and walnut orchards. The data can be used to provide accurate information about soil carbon stocks in perennial cropping systems for a future carbon trading system.
  • Authors:
    • Nan, Z.
    • Tang, Z.
  • Source: Mitigation and Adaptation Strategies for Global Change
  • Volume: 18
  • Issue: 7
  • Year: 2013
  • Summary: It is generally accepted that cropland soils could be managed to store significant carbon (C), however little information is available regarding the cropland soil C sequestration potential of the Loess Plateau in northern China. This study aimed to estimate the cropland soil C sequestration potential in this area using the United Nations Intergovernmental Panel on Climate Change (IPCC) method with region-specific C stock change factors. The results show that the C sequestration potential can reach 6.054 Tg C yr(-1) (1Tg = 10(12) g) in cropland soils of the Loess Plateau using techniques that are currently available (no-tillage and high residue incorporation). Although the results show a high degree of uncertainty in this estimate with 95 % confidence interval ranges from 2.623 to 11.94 Tg C yr(-1), our study suggests that cropland soil C sequestration could play a meaningful role in helping to mitigate greenhouse gas increases in the Chinese Loess Plateau.
  • Authors:
    • Liao, Y.
    • Zhang, J.
    • Lu, X. L.
    • Wen, X.
    • Tanveer, S. K.
  • Source: PLOS ONE
  • Volume: 8
  • Issue: 9
  • Year: 2013
  • Summary: A two year (2010-2012) study was conducted to assess the effects of different agronomic management practices on the emissions of CO2 from a field of non-irrigated wheat planted on China's Loess Plateau. Management practices included four tillage methods i.e. T-1: (chisel plow tillage), T-2: (zero-tillage), T-3: (rotary tillage) and T-4: (mold board plow tillage), 2 mulch levels i.e., M-0 (no corn residue mulch) and M-1 (application of corn residue mulch) and 5 levels of N fertilizer (0, 80, 160, 240, 320 kg N/ha). A factorial experiment having a strip split-split arrangement, with tillage methods in the main plots, mulch levels in the sub plots and N-fertilizer levels in the sub-sub plots with three replicates, was used for this study. The CO2 data were recorded three times per week using a portable GXH-3010E1 gas analyzer. The highest CO2 emissions were recorded following rotary tillage, compared to the lowest emissions from the zero tillage planting method. The lowest emissions were recorded at the 160 kg N/ha, fertilizer level. Higher CO2 emissions were recorded during the cropping year 2010-11 relative to the year 2011-12. During cropping year 2010-11, applications of corn residue mulch significantly increased CO2 emissions in comparison to the non-mulched treatments, and during the year 2011-12, equal emissions were recorded for both types of mulch treatments. Higher CO2 emissions were recorded immediately after the tillage operations. Different environmental factors, i.e., rain, air temperatures, soil temperatures and soil moistures, had significant effects on the CO2 emissions. We conclude that conservation tillage practices, i.e., zero tillage, the use of corn residue mulch and optimum N fertilizer use, can reduce CO2 emissions, give better yields and provide environmentally friendly options.