• Authors:
    • Below, F. E.
    • Moose, S.
  • Source: Biotechnology in Agriculture and Forestry
  • Volume: 63
  • Year: 2009
  • Summary: Nitrogen (N) is an essential and often limiting nutrient to plant growth. Maize grain yields are highly responsive to supplemental N, leading to annual application of an estimated 10 million metric tons of N fertilizer to the maize crop worldwide (FAO 2004). Nearly all cultivated maize in developed countries receives some form of N fertilizer and N use is increasing in developing countries, where its impacts on raising grain yields from nutrient-poor soils are greatest. The extensive use of N fertilizer not only increases crop input costs, but also can negatively impact soil, water and air quality at both local and ecosystem scales (Tilman et al. 2002). The manufacture of N fertilizer is an energy-intensive process that is becoming increasingly costly, due to the use of natural gas as both a reactant and heat source for the conversion of atmospheric N2 to anhydrous ammonia (NH3). For these reasons, reducing the amount of supplemental N used in maize production will have significant positive economic and environmental benefits to world agriculture. Nitrogen use efficiency (NUE) can be defined in a variety of ways that emphasize different components of the soil and plant system (reviewed in Good et al. 2004) or economic returns to fertilizer use. In cereal crops like maize, agronomic NUE is most simply expressed as the ratio of grain yield to N fertilizer supplied. Comparisons of maize grain yields and N fertilizer usage on a global basis lead to estimates of maize NUE ranging from 25-50% (Raun and Johnson 1999; Tilman et al. 2002), indicating that more than half the fertilizer N applied in maize crop production is lost to the environment. Thus, there is considerable opportunity for enhancing maize NUE.
  • Authors:
    • Edgerton, M. D.
  • Source: Plant Physiology
  • Volume: 149
  • Issue: 1
  • Year: 2009
  • Authors:
    • Huang, W.
    • Beckman, J.
    • Livingston, M. J.
    • Ribaudo, M. O.
    • MacDonald, J. M.
  • Year: 2009
  • Summary: The Food, Conservation, and Energy Act of 2008 directed the U.S. Department of Agriculture to evaluate the role of animal manure as a source of fertilizer, and its other uses. About 5 percent of all U.S. cropland is currently fertilized with livestock manure, and corn accounts for over half of the acreage to which manure is applied. Expanded environmental regulation through nutrient management plans will likely lead to wider use of manure on cropland, at higher production costs, but with only modest impacts on production costs, commodity demand, or farm structure. There is widespread interest in using manure as a feedstock for energy production. While current use is quite limited, expanded government support, either direct or indirectly, could lead to a substantial increase in manure use as a feedstock. However, current energy processes are unlikely to compete with fertilizer uses of manure, because they leave fertilizer nutrients as residues, in more marketable form, and because manure-to-energy projects will be most profitable in regions where raw manure is in excess supply, with the least value as fertilizer.
  • Authors:
    • Lorenz, N.
    • Eastridge, M. L.
    • Dick, R. P.
    • Barker, D. J.
    • Sulc, R. M.
    • Fae, G. S.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 5
  • Year: 2009
  • Summary: The benefits of cover crops within crop rotations are well documented, but information is limited on using cover crops for forage within midwestern United States cropping systems, especially under no-tillage management. Our objective was to evaluate plant, animal, and soil responses when integrating winter cover crop forages into no-till corn (Zea mays L.) silage production. Three cover crop treatments were established no-till after corn silage in September 2006 and 2007 at Columbus, OH: annual ryegrass (Lolium multiflorum L.), a mixture of winter rye (Secale cereale L.) and oat (Avena sativa L.), and no cover crop. Total forage yield over autumn and spring seasons was 38 to 73% greater (P <= 0.05) for oat + winter rye than for annual ryegrass. Soil penetration resistance (SPR) in May 2007 was 7 to 15% greater (P <= 0.10) in the grazed cover crops than in the nongrazed no cover crop treatment; however, subsequent silage corn yield did not differ among treatments, averaging 10.4 Mg ha(-1) in August 2007. Compared with the no cover crop treatment, cover crops had three- to fivefold greater root yield, threefold greater soil microbial biomass (MB) in spring 2008, and 23% more particulate organic carbon (POC) concentrations in the 0- to 15-cm soil depth. integration of forage cover crops into no-till corn silage production in Ohio can provide supplemental forage for animal feed without detrimental effects on subsequent corn silage productivity, with the added benefit of increasing labile soil C.
  • Authors:
    • Alluvione, F.
    • Del Grosso, S. J.
    • Halvorson, A. D.
  • Source: Better Crops with Plant Food
  • Volume: 93
  • Issue: 1
  • Year: 2009
  • Summary: Research shows that application of N fertilizer increases nitrous oxide (N2O) emissions linearly from irrigated cropping systems in Colorado. Conventional-till continuous corn had a higher level of N2O emissions than no-till continuous corn. Inclusion of soybean or dry bean in the no-till corn rotation increased the level of N2O emissions during the corn year of the rotation. Use of controlled release and stabilized N sources reduced N2O emissions under no-till when compared to urea and UAN fertilizer sources. Results of this work indicate that there are crop and fertilizer N management alternatives to reduce N2O emissions from irrigated systems.
  • Authors:
    • Reider, C.
    • Seidel, R.
    • Ulsh, C. Z.
    • Lotter, D.
    • Hepperly, P.
  • Source: Compost Science & Utilization
  • Volume: 17
  • Issue: 2
  • Year: 2009
  • Authors:
    • Brown, R. C.
    • Satrio, J. A.
    • Schmidt-Rohr, K.
    • Brewer, C. E.
  • Source: Environmental Progress & Sustainable Energy
  • Volume: 28
  • Issue: 3
  • Year: 2009
  • Summary: Thermochemical processing of biomass produces a solid product containing char (mostly carbon) and ash. This char can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. The most advantageous use of a given char depends on its physical and chemical characteristics, although the relationship of char properties to these applications is not well understood. Chars from fast pyrolysis and gasification of switchgrass and corn stover were characterized by proximate analysis, CHNS elemental analysis, Brunauer-Emmet-Teller (BET) surface area, particle density, higher heating value (HHV), scanning electron microscopy, X-ray fluorescence ash content analysis, Fourier transform infrared spectroscopy using a photo-acoustic detector (FTIR-PAS), and quantitative 13C nuclear magnetic resonance spectroscopy (NMR) using direct polarization and magic angle spinning. Chars from the same feedstocks produced under slow pyrolysis conditions, and a commercial hardwood charcoal, were also characterized. Switchgrass and corn stover chars were found to have high ash content (32-55 wt %), much of which was silica. BET surface areas were low (7-50 m2/g) and HHVs ranged from 13 to 21 kJ/kg. The aromaticities from NMR, ranging between 81 and 94%, appeared to increase with reaction time. A pronounced decrease in aromatic C---H functionality between slow pyrolysis and gasification chars was observed in NMR and FTIR-PAS spectra. NMR estimates of fused aromatic ring cluster size showed fast and slow pyrolysis chars to be similar (-7-8 rings per cluster), while higher-temperature gasification char was much more condensed (sim17 rings per cluster).
  • Authors:
    • Horwath, W.
    • Kallenbach, C.
    • Assa, J.
    • Burger, M.
  • Year: 2009
  • Authors:
    • Lu, Y.
    • Conklin, A. E.
    • Teasdale, J. R.
    • Hanson, J. C.
    • Hima, B. L.
    • Cavigelli, M. A.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 24
  • Issue: 2
  • Year: 2009
  • Summary: Interest in organic grain production is increasing in the United States but there is limited information regarding the economic performance of organic grain and forage production in the mid-Atlantic region. We present the results from enterprise budget analyses for individual crops and for complete rotations with and without organic price premiums for five cropping systems at the US Department of A(Agriculture-Agricultural Research Service (USDA-ARS) Beltsville Farming Systems Project (FSP) from 2000 to 2005. The FSP is a long-term cropping systems trial established in 1996 to evaluate the sustainability of organic and conventional grain crop production. The five FSP cropping systems include a conventional. three-year no-till corn (Zea mays L.)-rye (Secale cereale L.) cover crop/soybean (Glycine max (L.) Merr)-wheat (Triticum aestivum L.)/soybean rotation (no-till (NT)), a conventional, three-year chisel-till corn-rye/soybean-wheat/soybean rotation (chisel tillage (CT)), a two-year organic hairy vetch (Vicia villosa Roth)/corn-rye/soybean rotation (Org2), a three-year organic vetch/corn-rye/soybean-wheat rotation (Org3) and a four- to six-year organic corn-rye/soybean-wheat-red clover (Trifolium pratense L.)/orchard grass (Dactylis glomerata L.) or alfalfa (Medicago sativa L.) rotation (Org4+). Economic returns were calculated for rotations present from 2000 to 2005, which included some slight changes in crop rotation sequences due to weather conditions and management changes additional analyses were conducted for 2000 to 2002 when all crops described above were present in all organic rotations. Production costs were, in general, greatest for CT, while those for the organic systems were lower than or similar to those for NT for all crops. Present value of net returns for individual crops and for full rotations were greater and risks were lower for NT than for CT. When price premiums for organic crops were included in the analysis, cumulative present value of net returns for organic systems (US$3933 to 5446 ha(-1), 2000 to 2005. US$2653 to 2869 ha(-1), 2000 to 2002) were always Substantially greater than for the conventional systems (US$1309 to 1909 ha(-1),2000 to 2005; US$634 to 869 ha(-1), 2000 to 2002). With price premiums, Org2 had greater net returns but also greater variability of returns and economic risk across all years than all other systems, primarily because economic Success of this short rotation was highly dependent on the success of soybean, the crop with the highest returns. Soybean yield variability was high due to the impact of weather on the success of weed control in the organic systems. The longer, more diverse Org4+ rotation had the lowest variability of returns among organic systems and lower economic risk than Org2. With no organic price premiums, economic returns for corn and soybean in the organic systems were generally lower than those for the conventional systems due to lower grain yields in the organic systems. An exception to this pattern is that returns for corn in Org4+ were equal to or greater than those in NT in four of six years due to both lower production costs and greater revenue than for Org2 and Org3. With no organic premiums, present value of net returns for the full rotations was greatest for NT in 4 of 6 years and greatest for Org4+ the other 2 years, when returns for hay crops were high. Returns for individual crops and for full rotations were, in general, among the lowest and economic risk was, in general, among the highest for Org2 and Org3. Results indicte that Org4+, the longest and most diverse rotation, had the most stable economic returns among organic systems but that short-term returns could be greatest with Org2. This result likely explains, at least in part, why some organic farmers in the mid-Atlantic region, especially those recently converting to organic methods, have adopted this relatively short rotation. The greater stability of the longer rotation, by contrast, may explain why farmers who have used organic methods for longer periods of time tend to favor rotations that include perennial forages.
  • Authors:
    • Lal, R.
    • Chatterjee, A.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 2
  • Year: 2009
  • Summary: No-tillage (NT) farming offers innumerable benefits to soil and water conservation, however, its potential to sequester soil organic carbon (SOC) and related soil properties varies widely. Thus, the impact of long-term (>4 yr) NT-based cropping systems on SOC sequestration and selected soil physical and chemical parameters were assessed across soils within five Major land Resource Areas (MLRAs: 99 and 111 in Michigan; 124 and 139 in Ohio; and 127 in Pennsylvania) in eastern U.S.A. Soil samples were collected from paired fields of NT and plow tillage (PT) based cropping systems and an adjacent woodlot (WL). The SOC concentration, bulk density (rho(b)), texture, pH, electrical conductivity (EC), soil N, coarse particulate organic matter (CPOM) C and N, and nitrate N (NO3-N) concentrations were determined. Conversion from NT to PT practice increased surface soil pH from 5.97,6.56 and 6.02 to 6.62, 6.91 and 7.09 under MLRAs 127, 111 and 99, respectively. NT soils had higher SOC concentration soils by 30,50 and 67% over PT soils at 0-5 cm depth under MLRAs 99, 111 and 127, respectively. Considering the whole soil profile SOC, WL had higher SOC pool than NT and PT practices under MLRAs 99, 111 and 124, however, there was no significant difference (P < 0.05) between NT and PT practices across five soils. Almost the same trend was observed in the case of depthwise soil N content. NT soil had higher N content than PT soils by 27,44 and 54% under MLRAs 99,127 and 111, respectively. However, whole soil profile N content of NT soil was significantly higher by 12% than PT soil under MLRA 99. Concentrations of CPOM associated C and N of NT soil was higher than PT soil under MLRAs 99. 111 and 127 at 0-5 soil depth. These results indicated that impact of tillage on soil C and associated soil quality parameters is confined within specific soil types. (C) 2009 Elsevier B.V. All rights reserved.