• Authors:
    • Lence, S.
    • Livingston, M.
    • Greene, C.
    • Chase, C.
    • Delate, K.
    • Singerman, A.
    • Hart, C.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: 4
  • Year: 2012
  • Summary: Emphasis on reducing emissions from the greenhouse gases (GHG), carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) has increased in recent years in the USA, primarily for industry, transportation, energy and agricultural sectors. In this study, we utilized on-farm data collected by the USDA-National Agricultural Statistics Service (NASS) Agricultural Resource Management Survey (ARMS), secured under an agreement with the USDA-Economic Research Service (ERS) to analyze the profitability of organic and conventional soybean production, based on changes that 'green payments' in a cap-and-trade system would introduce in agricultural markets in the USA. In particular, the analysis focused on establishing whether organic producers would be better positioned to sequester carbon (C) and reap the benefits of the C-offset scheme compared to conventional producers, given the differences in costs, management practices and environmental benefits between organic and conventional production methods. We estimated several changes in profitability of soybean producers according to management practices, incentives for the generation of offset credits, and increase in energy input prices that a potential cap-and-trade system may introduce in future agricultural markets in the USA. Survey data suggested that even with lower yields, conventional producers could profit from converting to organic agriculture, given organic price premiums. In addition, taking into consideration both direct and indirect costs, average cost for conventional-till (CT) organic soybean production was approximately 9% lower than no-till (NT) conventional production. With a C market and payments for soil C sequestration through potential Clean Energy legislation, additional profit could be accrued by organic producers, because organic production would have 28% greater ton CO2 eq. acre(-1) yr(-1) sequestration than conventional NT. Thus, the environmental benefits from GHG reduction could incentivize increased conversion from conventional to organic production across the USA.
  • Authors:
    • Fernando, L. K.
    • Banuwa, I. S.
    • Buchari, H.
    • Utomo, M.
    • Saleh, R.
  • Source: Journal of Tropical Soils
  • Volume: 17
  • Issue: 1
  • Year: 2012
  • Summary: Although agriculture is a victim of environmental risk due to global warming, but ironically it also contributes to global greenhouse gas (GHG) emission. The objective of this experiment was to determine the influence of long-term conservation tillage and N fertilization on soil carbon storage and CO2 emission in corn-soybean rotation system. A factorial experiment was arranged in a randomized completely block design with four replications. The first factor was tillage systems namely intensive tillage (IT), minimum tillage (MT) and no-tillage (NT). While the second factor was N fertilization with rate of 0, 100 and 200 kg N ha -1 applied for corn, and 0, 25, and 50 kg N ha -1 for soybean production. Samples of soil organic carbon (SOC) after 23 year of cropping were taken at depths of 0-5 cm, 5-10 cm and 10-20 cm, while CO2 emission measurements were taken in corn season (2009) and soybean season (2010). Analysis of variance and means test (HSD 0.05) were analyzed using the Statistical Analysis System package. At 0-5 cm depth, SOC under NT combined with 200 kg N ha -1 fertilization was 46.1% higher than that of NT with no N fertilization, while at depth of 5-10 cm SOC under MT was 26.2% higher than NT and 13.9% higher than IT. Throughout the corn and soybean seasons, CO2-C emissions from IT were higher than those of MT and NT, while CO2-C emissions from 200 kg N ha -1 rate were higher than those of 0 kg N ha -1 and 100 kg N ha -1 rates. With any N rate treatments, MT and NT could reduce CO2-C emission to 65.2%-67.6% and to 75.4%-87.6% as much of IT, respectively. While in soybean season, MT and NT could reduce CO2-C emission to 17.6%-46.7% and 42.0%-74.3% as much of IT, respectively. Prior to generative soybean growth, N fertilization with rate of 50 kg N ha -1 could reduce CO2-C emission to 32.2%-37.2% as much of 0 and 25 kg N ha -1 rates.
  • Authors:
    • Roose-Amsaleg, C.
    • Garnier, J.
    • Vilain, G.
    • Laville, P.
  • Source: Web Of Knowledge
  • Volume: 92
  • Issue: 1
  • Year: 2012
  • Summary: The denitrification process and the associated nitrous oxide (N(2)O) production in soils have been poorly documented, especially in terms of soil profiles; most work on denitrification has concentrated on the upper layer (first 20 cm). The objectives of this study were to examine the origin of N(2)O emission and the effects of in situ controlling factors on soil denitrification and N(2)O production, also allowing the (N(2)O production)/(NO(3) (-)-N reduction) ratio to be determined through (1) the position on a slope reaching a river and (2) the depth (soil horizons: 10-30 and 90-110 cm). In 2009 and 2010, slurry batch experiments combined with molecular investigations of bacterial communities were conducted in a corn field and an adjacent riparian buffer strip. Denitrification rates, ranging from 0.30 mu g NO(3) (-)-N g(-1) dry soil h(-1) to 1.44 mu g NO(3) (-)-N g(-1) dry soil h(-1), showed no significant variation along the slope and depth. N(2)O production assessed simultaneously differed considerably over the depth and ranged from 0.4 ng N(2)O-N g(-1) dry soil h(-1) in subsoils (the 90-110-cm layer) to 155.1 ng N(2)O-N g(-1) dry soil h(-1) in the topsoils (the 10-30-cm layer). In the topsoils, N(2)O-N production accounted for 8.5-48.0% of the total denitrified NO(3) (-)-N, but for less than 1% in the subsoils. Similarly, N(2)O-consuming bacterial communities from the subsoils greatly differed from those of the topsoils, as revealed by their nosZ DGGE fingerprints. High N(2)O-SPPR (nitrous oxide semi potential production rates) in comparison to NO(3)-SPDR (nitrate semi potential reduction rates) for the topsoils indicated significant potential greenhouse N(2)O gas production, whereas lower horizons could play a role in fully removing nitrate into inert atmospheric N(2). In terms of landscape management, these results call for caution in rehabilitating or constructing buffer zones for agricultural nitrate removal.
  • Authors:
    • Van Pelt, R. S.
    • Rice, C. W.
    • Nielsen, D.
    • Gulliford, J.
    • Delgado, J. A.
    • Lal, R.
  • Source: Journal of Soil and Water Conservation
  • Volume: 67
  • Issue: 6
  • Year: 2012
  • Authors:
    • Urquiaga, S.
    • Martellotto, E. E.
    • Jantalia, C. P.
    • Alves, B. J. R.
    • Alvarez, C. R.
    • Costantini, A.
    • Alvarez, C.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 94
  • Issue: 2-3
  • Year: 2012
  • Summary: The aim of this study was to analyze the influence of different crop sequences (soybean-corn and soybean-soybean) and tillage systems (no tillage and reduced tillage) on nitrous oxide (N2O) soil emissions under field conditions. The experiment was carried out in Manfredi, Crdoba province, Argentina on an Entic Haplustoll and N2O emissions were measured in the field during a year. N2O fluxes were low during winter, but in late spring it peaked. For fallow, N-NO3-content was the most important variable to explain N2O emissions. For growing period water-filled pores was the main variable explaining N2O emissions. Nitrogen fertilization of corn crop increased N2O-N emissions, whereas no significant differences were found due to the tillage system. Measured annual N2O-N emissions were generally lower than those calculated using the methodology proposed by the Intergovernmental Panel on Climate Change.
  • Authors:
    • Ahuja, L. R.
    • Hatfield, J. L.
    • Ma, L.
    • Malone, R. W.
    • Heiman, P.
    • Boyle, K. P.
    • Kanwar, R. S.
  • Source: Agricultural Systems
  • Volume: 106
  • Issue: 1
  • Year: 2012
  • Summary: A 45% reduction in riverine total nitrogen flux from the 1980-1996 time period is needed to meet water quality goals in the Mississippi Basin and Gulf of Mexico. This paper addresses the goal of reducing nitrogen in the Mississippi River through three objectives. First, the paper outlines an approach to the site-specific quantification of management effects on nitrogen loading from tile drained agriculture using a simulation model and expert review. Second, information about the net returns to farmers is integrated with the nitrogen loading information to assess the incentives to adopt alternative management systems. Third, the results are presented in a decision support framework that compares the rankings of management systems based on observed and simulated values for net returns and nitrogen loading. The specific question addressed is how information about the physical and biological processes at Iowa State University's Northeast Research Farm near Nashua, Iowa, could be applied over a large area to help farmers select management systems to reduce nitrogen loading in tile drained areas. Previous research has documented the parameterization and calibration of the RZWQM model at Nashua to simulate 35 management system effects on corn and soybean yields and N loading in tileflow from 1990 to 2003. As most management systems were studied for a 6 year period and in some cases weather had substantial impacts, a set of 30 alternative management systems were also simulated using a common 1974-2003 input climate dataset. To integrate an understanding of the economics of N management, we calculated net returns for all management systems using the DevTreks social budgeting tool. We ranked the 35 observed systems in the Facilitator decision support tool using N loading and net returns and found that rankings from simulated results were very similar to those from the observed results from both an onsite and offsite perspective. We analyzed the effects of tillage, crop rotation, cover crops, and N application method, timing, and amount for the 30 long term simulations on net returns and N loading. The primary contribution of this paper is an approach to creating a quality assured database of management effects on nitrogen loading and net returns for tile drained agriculture in the Mississippi Basin. Such a database would systematically extend data from intensively monitored agricultural fields to the larger area those fields represent. Published by Elsevier Ltd.
  • Authors:
    • Singer, J. W.
    • Moorman, T. B.
    • Parkin, T. B.
    • Jaynes, D. B.
    • Kaspar, T. C.
  • Source: Agricultural Water Management
  • Volume: 110
  • Year: 2012
  • Summary: Much of the NO3 in the riverine waters of the upper Mississippi River basin in the United States originates from agricultural land used for corn (Zea mays L) and soybean (Glycine max [L] Merr.) production. Cover crops grown between maturity and planting of these crops are one approach for reducing losses of NO3. In this experiment, we evaluated the effectiveness of oat (Avena sativa L.) and rye (Secale cereale L.) cover crops in reducing NO3 concentrations and loads in subsurface drainage water. The oat fall cover crop was broadcast seeded into living corn and soybean crops before harvest in late August or early September and was killed by cold temperatures in late November or early December The rye winter cover crop, which had already been used annually for four years, was planted with a grain drill after corn and soybean harvest, overwintered, grew again in the spring, and was killed with herbicides before main crop planting. These treatments were evaluated in subsurface-drained field plots with an automated system for measuring drainage flow and collecting proportional samples for analysis of NO3 concentrations from each plot. The rye winter cover crop significantly reduced drainage water NO3 concentrations by 48% over five years, but this was less than the 58% reduction observed in its first four years of use. The oat fall cover crop reduced NO3 concentrations by 26% or about half of the reduction of the rye cover crop. Neither cover crop significantly reduced cumulative drainage or nitrate loads because of variability in cumulative annual drainage among plots. Both oat and rye cover crops are viable management options for significantly reducing NO3 losses to surface waters from agricultural drainage systems used for corn and soybean production. Published by Elsevier B.V.
  • Authors:
    • Lawton-Rauh, A.
    • Agudelo, P.
    • Leach, M.
  • Source: Plant Disease
  • Volume: 96
  • Issue: 1
  • Year: 2012
  • Summary: Rotylenchulus reniformis is a highly variable nematode species and an economically important pest in many cotton fields across the southeastern United States. Rotation with resistant or poor host crops is a method for management of reniform nematode. We studied the effect of six planting schemes covering four 120-day planting cycles on the predominant genotype of R. reniformis. Rotations used were: (i) cotton to corn; (ii) susceptible soybean to corn; (iii) resistant soybean to cotton; (iv) corn to cotton; (v) continuous susceptible soybean; (vi) continuous cotton. After each 120-day cycle, amplified fragment length polymorphisms (AFLPs) produced from four primer pairs were used to determine the effect of crop rotation on the predominant genotype of reniform nematode. A total of 279 polymorphic bands were scored using four primer combinations. Distinct changes in genotype composition were observed following rotations with resistant soybean or corn. Rotations involving soybean (susceptible and resistant) had the greatest effect on population structure. The characterization of field population variability of reniform nematode and of population responses to host plants used in rotations can help extend the durability of resistant varieties and can help identify effective rotation schemes.
  • Authors:
    • Asebedo, R.
    • Ruiz-Diaz, D.
    • Mengel, D.
    • Maxwell, T.
  • Source: Better Crops with Plant Food
  • Volume: 96
  • Issue: 1
  • Year: 2012
  • Summary: Soybeans are not generally considered responsive to N fertilizer; however, there are some circumstances where this crop can benefit from addition of N. Kansas research performed several years ago and reported in this magazine showed the potential for soybean grain response to N fertilizer in high-yield irrigated conditions. This article looks at other conditions where N fertilizer can be beneficial in soybean production.
  • Authors:
    • Newman, M. A.
    • Canaday, C. H.
    • Little, C. R.
    • Chen, P.
    • Rupe, J. C.
    • Wrather, A. J.
    • Shannon, G. J.
    • Bond, J. P.
    • Bellaloui, N.
    • Arelli, P. A.
    • Mengistu, A.
    • Pantalone, V. R.
  • Source: Plant Health Progress
  • Issue: March
  • Year: 2012
  • Summary: Seed-borne diseases of soybeans caused by Phomopsis longicolla (Phomopsis seed decay), Cercospora kukuchii (purple seed stain), and M. phaseolina (charcoal rot) are economically important diseases that affect seed quality. Commercial cultivars marketed as resistant to all three diseases are not available. Reactions of 27 maturity group (MG) III, 30 early MG IV, 33 late MG IV, and 53 MG V genotypes were evaluated for resistance to these pathogens during the 2006 to 2008 growing season in the same field that had been in no-till production, not irrigated, and naturally and artificially infested. There was great variation in seed infection among genotypes and years, indicating the value of screening genotypes over multiple years. Some genotypes were resistant to these pathogens in one, two, or in all three years. Genotypes, DP 3478 (early MG IV), and RO1-769F (MG V) were resistant and DG4460 was moderately resistant to P. longicolla infection across three years. Genotypes AG3705 and FFR3990 (MG III) and DC20300, DC7816, Stoddard, and Ozark (MG V), were resistant to C. kukuchii infection during all three years. Ten genotypes in MG III, eight in early MG IV, seven in late MG IV, and 14 in MG V had no seed infection by M. phaseolina in all three years. These results indicate that seed infection comparison to these pathogens among genotypes should be made over several years, or false conclusions about resistance to any of the three pathogens may be made when disease is assessed for limited period of time. The genotypes identified as having resistance to each or combinations of the seed-borne diseases across the three years could be useful as a source for resistance in improving soybean seed quality.