• Authors:
    • Edis, R. B.
    • Park, K.
    • Meyer, M.
    • Kirkby, C.
    • Chen, D.
    • Wang, G.
    • Turner, D. A.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 48
  • Issue: 3
  • Year: 2008
  • Authors:
    • Endale, D. M.
    • Schomberg, H. H.
    • Fisher, D. S.
    • Jenkins, M. B.
    • Sharpe, R. R.
    • Cabrera, M. L.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 5
  • Year: 2008
  • Summary: Corn (Zea mays L.) producers in the southeastern United States must overcome soil and water limitations to take advantage of the expanding corn market. In this 2001 to 2005 study on a Cecil sandy loam (fine, kaolinitic, thermic Typic Kanhapludult) near Watkinsville, GA, we compared dry land corn biomass and yield under conventional tillage (CT) vs. no-tillage (NT) with ammonium nitrate or sulfate (based on availability) as conventional fertilizer (CF) vs. poultry litter (PL). In a randomized complete block split plot design with three replications, main plots were under tillage and subplots under fertilizer treatments. The cover crop was rye (Secale cereale L.). Over 5 yr, NT and PL increased grain yield by 11 and 18%, respectively, compared with CT and CF. Combined, NT and PL increased grain yield by 31% compared with conventionally tilled and fertilized corn. Similarly, soil water was 18% greater in NT than CT in the 0- to 10-cm depth. In 2 yr of measurements, dry matter of stalks and leaves and leaf area index under PL were an average of 39 and 22% greater, respectively, than under CF during reproduction. Values were 21 and 6% greater, respectively, under NT than CT but during tasseling. Analysis of 70 yr of daily rainfall records showed that supplemental irrigation is needed to meet optimal water requirement. Our results indicate that corn growers can use rainfall more efficiently, reduce yield losses to drought, and expect increased corn yields with a combination of no-tillage management and long-term use of poultry litter.
  • Authors:
    • Kang, J.
    • Osmond, D. L.
  • Year: 2008
  • Authors:
    • Reddy, K. C.
    • Tazisong, I. A.
    • Nyakatawa, E. Z.
    • Senwo, Z. N.
    • Sainju, U. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 127
  • Issue: 3-4
  • Year: 2008
  • Summary: Disposal of poultry litter, a widely available organic manure in the southeastern USA because of a large-scale poultry industry, is a major concern because of its contamination in surface- and groundwater through N leaching and P runoff. Application of poultry litter in no-tilled intensive cropping system could increase soil C and N sequestration compared with the conventional-tilled system with inorganic N fertilization and reduce environmental contamination. We evaluated the 10-year effects of tillage, cropping systems, and N fertilizer sources on crop residue (stems + leaves) production and soil bulk density, organic C (SOC), and total N (STN) at the 0-20 cm depth in Decatur silt loam (clayey, kaolinitic, thermic, and Typic Paleudults) in northern AL, USA. Treatments were incomplete factorial combinations of three tillage practices [no-till (NT), mulch till (MT), and conventional till (CT)], two cropping systems [cotton (Gossypium hirsutum L.)-cotton-corn (Zea mays Q and rye (Secale cereale L.)/cotton-rye/cotton-corn], and two N fertilization sources and rates (0 and 100 kg N ha(-1) from NH4NO3, and 100 and 200 kg N ha(-1) from poultry litter) in randomized complete block with three replications. Rye was grown as winter cover crop and corn as residual crop without tillage and fertilization. Mean crop residue returned to the soil from 1997 to 2005 was greater in rye/cotton-rye/cotton-corn than in cotton-cotton-corn and greater with NH4NO3 than with poultry litter at 100 kg N ha(-1). While SOC and STN concentrations at 10-20 cm after 10 years were not influenced by treatments, SOC and STN contents at 0-20 cm were greater with poultry litter than with NH4NO3 in NT and CT. These resulted in a C sequestration rate of 510 kg C ha(-1) year(-1) and N sequestration rates of 41-49 kg N ha(-1) year(-1) with poultry litter compared with -120 to 147 kg C ha(-1) year(-1) and -23 to -3 kg N ha(-1) year(-1), respectively, with NH4NO3. Cropping and fertilization sequestered C at 730 kg C ha(-1) year(-1) and N at 67 kg N ha(-1) year(-1) compared with fallow and no-fertilization in NT. Tillage and cropping system did not influence SOC and STN. Long-term poultry litter application or continuous cropping can sequester C and N in the soil compared with inorganic N fertilization or fallow, thereby increasing soil quality and productivity and reducing the potentials for N leaching and greenhouse gas emission. Published by Elsevier B.V.
  • Authors:
    • Place, F.
    • Ajayi, O. C.
    • Akinnifesi, F. K.
    • Sileshi, G.
  • Source: Plant and Soil
  • Volume: 307
  • Issue: 1-2
  • Year: 2008
  • Summary: A number of studies have tested the effect of woody and herbaceous legumes on soil fertility and maize yields in sub-Saharan Africa. However, their effects on maize productivity are much debated because results have been variable. A meta-analysis was conducted with the aim of evaluating the evidence in support of yield benefits from woody and herbaceous green manure legumes. A total of 94 peer-reviewed publications from West, East and southern Africa qualified for inclusion in the analysis. Maize yield from herbaceous green manure legumes (54 publications), non-coppicing legumes (48 publications), coppicing woody legumes (10 publications), natural fallows (29 publications), and fully fertilized monoculture maize (52 publications) were compared. Mixed linear modelling using yield differences (D) and response ratios (RR) indicated that the response to legumes is positive. The mean yield increase (D) over unfertilized maize was highest (2.3 t ha-1) and least variable (CV=70%) in fully fertilized maize, while it was lowest (0.3 t ha-1) and most variable (CV=229%) in natural fallows. The increase in yield over unfertilized maize was 1.6 t ha-1 with coppicing woody legumes, 1.3 t ha-1 with non-coppicing woody legumes and 0.8 t ha-1 with herbaceous green manure legumes. Doubling and tripling of yields relative to the control (RR > 2) was recorded in coppicing species (67% of the cases), non-coppicing legumes (45% of the cases), herbaceous green manure legumes (16% of the cases) and natural fallows (19% of the cases). However, doubling or tripling of yields occurred only in low and medium potential sites. Amending post-fallow plots with 50% of the recommended fertilizer dose further increased yields by over 25% indicating that legume rotations may play an important role in reducing fertilizer requirements. Except with the natural fallow, the 95% confidence intervals of D and RR were higher than 1 and 0, respectively indicating significant and positive response to treatments. Therefore, it is concluded that the global maize yield response to legumes is significantly positive and higher than unfertilized maize and natural vegetation fallows.
  • Authors:
    • Snyder, C. S.
  • Year: 2008
  • Summary: The discussion and guides that follow are oriented toward the central U.S. Corn Belt, but are relevant to other cropping systems with similar crop geographies. They are provided to assist in fertilizer nitrogen (N) management decisions that will help lessen the impact of fertilizer N use on greenhouse gas (GHG) emissions and help mitigate the global warming potential (GWP) - expressed as CO2 equivalent. The three GHGs of interest to agriculture are: nitrous oxide (N2O), methane (CH4), and CO2. The GWP of CH4 is 23 times greater and the GWP of N2O is 296 times greater than that of CO2. Because fertilizer N use may be associated with N2O emissions, and because the GWP of N2O is so much greater than CO2, fertilizer N BMPs to reduce N2O emissions are emphasized in this practical guide. For example, fertilizer N BMPs which help minimize excess nitrate (NO3 -) in the soil during warm, wet, or waterlogged conditions can result in lowered risks for N2O emission.
  • Authors:
    • Snyder, K.
    • Sims, P. L.
    • Schuman, G. E.
    • Saliendra, N. Z.
    • Morgan, J. A.
    • Mielnick, P.
    • Mayeux, H.
    • Johnson, D. A.
    • Haferkamp, M.
    • Gilmanov, T. G.
    • Frank, A. B.
    • Emmerich, W.
    • Dugas, W.
    • Bradford, J. A.
    • Angell, R.
    • Svejcar, T.
  • Source: Rangeland Ecology & Management
  • Volume: 61
  • Issue: 5
  • Year: 2008
  • Summary: Rangelands account for almost half of the earth's land surface and may play an important role in the global carbon (C) cycle. We Studied net ecosystem exchange (NEE) of C on eight North American rangeland sites over a 6-yr period. Management practices and disturbance regimes can influence NEE; for consistency, we compared ungrazed and undisturbed rangelands including four Great Plains sites from Texas to North Dakota, two Southwestern hot desert sites in New Mexico and Arizona, and two Northwestern sagebrush steppe sites in Idaho and Oregon. We used the Bowen ratio-energy balance system for continuous measurements of energy, water vapor, and carbon dioxide (CO2) fluxes at each study site during the measurement period (1996 to 2001 for most sites). Data were processed and screened using standardized procedures, which facilitated across-location comparisons. Although almost any site could be either a sink or source for C depending on yearly weather patterns, five of the eight native rangelands typically were sinks for atmospheric CO2 during the study period. Both sagebrush steppe sites were sinks and three of four Great Plains grasslands were sinks, but the two Southwest hot desert sites were sources of C on an annual basis. Most rangelands were characterized by short periods of high C uptake (2 mo to 3 mo) and long periods of C balance or small respiratory losses of C. Weather patterns during the measurement period strongly influenced conclusions about NEE on any given rangeland site. Droughts tended to limit periods of high C uptake and thus cause even the most productive sites to become sources of C on an annual basis. Our results show that native rangelands are a potentially important terrestrial sink for atmospheric CO2, and maintaining the period of active C uptake will be critical if we are to manage rangelands for C sequestration.
  • Authors:
    • Toderi, G.
    • Baldoni, G.
    • Comellini, F.
    • Giordani, G.
    • Nastri, A.
    • Triberti, L.
  • Source: European Journal of Agronomy
  • Volume: 29
  • Issue: 1
  • Year: 2008
  • Summary: The soil organic matter content represents a huge reservoir of plant nutrients and an effective safeguard against pollution; beside it can sequestrate atmospheric CO2. Since 1966 up to now in the Southeast Po valley (Italy), the soil organic C (SOC) and total N (TN) dynamics in the 0-0.40 m soil layer under a maize-wheat rainfed rotation are studied as influenced by organic and mineral N fertilizations. Every year in the same plots cattle manure, cattle slurry, and crop residues (i.e. wheat straw and maize stalk) are ploughed under to 0.40 m depth at a same dry matter rate (6.0 and 7.5 t DM ha-1 year-1 wheat and maize, respectively) and are compared to an unamended control. Each plot is splitted to receive four rates of mineral fertilizer (0-100-200-300 kg N ha-1). In the whole experiment, in 2000 SOC concentration was lower than in 1966 (6.77 and 7.72 g kg-1, respectively), likely for the deeper tillage that diluted SOC and favoured mineralization in deeper soil layer. From 1972 to 2000 SOC stock did not change in the control and N fertilized plots, while it increased at mean rates of 0.16, 0.18, and 0.26 t ha-1 year-1 with the incorporation of residues, slurry and manure, corresponding to sequestration efficiencies of 3.7, 3.8 and 8.1% of added C with the various materials. TN followed the same SOC dynamic, demonstrating how it depends on the soil organic matter. Manure thus confirmed its efficacy in increasing both SOC content and soil fertility on the long-term. In developed countries, however, this material has become scarcely available; slurry management is expensive and implies high environmental risks. Moreover, in a C balance at a farm (or regional) scale, the CO2 lost during manure and slurry stocking should be considered. For these reasons, the incorporation of cereal residues, even if only a little of their C content was found capable of soil accumulation, appears the best way to obtain a significant CO2 sequestration in developed countries. Our long-term experiment clearly shows how difficult it is to modify SOC content. Moreover, because climate and soil type can greatly influence SOC dynamic, to increase CO2 sequestration in cropland, it is important to optimize the fertilization within an agricultural management that includes all the agronomic practices (e.g. tillage, water management, cover crops, etc.) favouring the organic matter build up in the soil.
  • Authors:
    • Vives, C. A.
    • Szogi, A. A.
    • Vanotti, M. B.
  • Source: Waste Management
  • Volume: 28
  • Issue: 4
  • Year: 2008
  • Summary: Trading of greenhouse gas (GHG) emission reductions is an attractive approach to help producers implement cleaner treatment technologies to replace current anaerobic lagoons. Our objectives were to estimate greenhouse gas (GHG) emission reductions from implementation of aerobic technology in USA swine farms. Emission reductions were calculated using the approved United Nations framework convention on climate change (UNFCCC) methodology in conjunction with monitoring information collected during full-scale demonstration of the new treatment system in a 4360-head swine operation in North Carolina (USA). Emission sources for the project and baseline manure management system were methane (CH4) emissions from the decomposition of manure under anaerobic conditions and nitrous oxide (N2O) emissions during storage and handling of manure in the manure management system. Emission reductions resulted from the difference between total project and baseline emissions. The project activity included an on-farm wastewater treatment system consisting of liquid-solid separation, treatment of the separated liquid using aerobic biological N removal, chemical disinfection and soluble P removal using lime. The project activity was completed with a centralized facility that used aerobic composting to process the separated solids. Replacement of the lagoon technology with the cleaner aerobic technology reduced GHG emissions 96.9%, from 4972 tonnes of carbon dioxide equivalents (CO2-eq) to 153 tonnes CO2-eq/year. Total net emission reductions by the project activity in the 4360-head finishing operation were 4776.6 tonnes CO2-eq per year or 1.10 tonnes CO2-eq/head per year. The dollar value from implementation of this project in this swine farm was US$19,106/year using current Chicago Climate Exchange trading values of US$4/t CO2. This translates into a direct economic benefit to the producer of US$1.75 per finished pig. Thus, GHG emission reductions and credits can help compensate for the higher installation cost of cleaner aerobic technologies and facilitate producer adoption of environmentally superior technologies to replace current anaerobic lagoons in the USA. Published by Elsevier Ltd.
  • Authors:
    • Laird, D. A.
  • Source: Agronomy Journal
  • Volume: 100
  • Issue: 1
  • Year: 2008
  • Summary: Processing biomass through a distributed network of fast pyrolyzers may be a sustainable platform for producing energy from biomass. Fast pyrolyzers thermally transform biomass into bio-oil, syngas, and charcoal. The syngas could provide the energy needs of the pyrolyzer. Bio-oil is an energy raw material ([~]17 MJ kg-1) that can be burned to generate heat or shipped to a refinery for processing into transportation fuels. Charcoal could also be used to generate energy; however, application of the charcoal co-product to soils may be key to sustainability. Application of charcoal to soils is hypothesized to increase bioavailable water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent, and reduce leaching of pesticides and nutrients to surface and ground water. The half-life of C in soil charcoal is in excess of 1000 yr. Hence, soil-applied charcoal will make both a lasting contribution to soil quality and C in the charcoal will be removed from the atmosphere and sequestered for millennia. Assuming the United States can annually produce 1.1 x 109 Mg of biomass from harvestable forest and crop lands, national implementation of The Charcoal Vision would generate enough bio-oil to displace 1.91 billion barrels of fossil fuel oil per year or about 25% of the current U.S. annual oil consumption. The combined C credit for fossil fuel displacement and permanent sequestration, 363 Tg per year, is 10% of the average annual U.S. emissions of CO2-C.