• Authors:
    • Cavigelli, M. A.
    • Szlavecz, K.
    • Clark, S.
    • Purrington, F.
  • Source: Environmental Entomology
  • Volume: 35
  • Issue: 5
  • Year: 2006
  • Summary: Ground beetle assemblages were compared in organic, no-till, and chisel-till cropping systems of the USDA Farming Systems Project in Maryland. The cropping systems consisted of 3-yr rotations of corn ( Zea mays L.), soybean ( Glycine max L. Merr.), and wheat ( Triticum aestivum L.) that were planted to corn and soybean during the 2 yr of field sampling (2001-2002). Each year, ground beetles were sampled using pitfall traps during three 9- to 14-d periods corresponding to spring, summer, and fall. A total of 2,313 specimens, representing 31 species, were collected over the 2 yr of sampling. The eight most common species represented 87% of the total specimens collected and included Scarites quadriceps Chaudoir, Elaphropus anceps (LeConte), Bembidion rapidum (LeConte), Harpalus pensylvanicus (DeGeer), Poecilus chalcites (Say), Clivina impressefrons LeConte, Agonum punctiforme (Say), and Amara aenea (DeGeer). Canonical variates analysis based on the 10 most abundant species showed that the carabid assemblages in the three cropping systems were distinguishable from each other. The organic system was found to be more different from the no-till and chisel-till systems than these two systems were from each other. In 2002, ground beetle relative abundance, measured species richness, and species diversity were greater in the organic than in the chisel-till system. Similar trends were found in 2001, but no significant differences were found in these measurements. Relatively few differences were found between the no-till and chisel-till systems. The estimated species richness of ground beetles based on several common estimators did not show differences among the three cropping systems. The potential use of ground beetles as ecological indicators is discussed.
  • Authors:
    • Cook, R. J.
  • Source: PNAS, Proceedings of the National Academy of Sciences
  • Volume: 103
  • Issue: 49
  • Year: 2006
  • Summary: The defining features of any cropping system are (i) the crop rotation and (ii) the kind or intensity of tillage. The trend worldwide starting in the late 20th century has been (i) to specialize competitively in the production of two, three, a single, or closely related crops such as different market classes of wheat and barley, and (ii) to use direct seeding, also known as no-till, to cut costs and save soil, time, and fuel. The availability of glyphosate- and insect-resistant varieties of soybeans, corn, cotton, and canola has helped greatly to address weed and insect pest pressures favored by direct seeding these crops. However, little has been done through genetics and breeding to address diseases caused by residue- and soil-inhabiting pathogens that remain major obstacles to wider adoption of these potentially more productive and sustainable systems. Instead, the gains have been due largely to innovations in management, including enhancement of root defence by antibiotic-producing rhizosphere-inhabiting bacteria inhibitory to root pathogens. Historically, new varieties have facilitated wider adoption of new management, and changes in management have facilitated wider adoption of new varieties. Although actual yields may be lower in direct-seed compared with conventional cropping systems, largely due to diseases, the yield potential is higher because of more available water and increases in soil organic matter. Achieving the full production potential of these more-sustainable cropping systems must now await the development of varieties adapted to or resistant to the hazards shown to account for the yield depressions associated with direct seeding.
  • Authors:
    • Vyn, T.
    • Janovicek, K.
    • Deen, B.
    • Lapen, D.
  • Source: ADVANCES IN GEOECOLOGY
  • Volume: 38
  • Year: 2006
  • Summary: In corn/soybean/wheat rotations in Ontario, Canada, tillage is often conducted intermittently to remediate compaction, address residues, incorporate nutrients or to level the surface. To determine the impact of intermittent tillage on no-till soil structure and crop yield, a 10-year study was initiated in 1995 at the Woodstock Research Station, University of Guelph. Specific objectives were (1) to compare the yield potential of corn, soyabean and wheat under short term and long-term no-till, and (2) to determine the best time to conduct intermittent tillage in a corn/soybean/wheat rotation. Tillage increased corn, soyabean and wheat yields in comparison to both short-term and long-term no-till. No-till soyabean yields did not improve with increasing years under no-till. Corn yields were reduced under first year no-till, but by the second year of no-till, corn yields were equal to long term no-till yields. In a corn/soybean/wheat rotation occasional tillage should be conducted in advance of corn.
  • Authors:
    • Easterly, J. L.
    • Haq, Z.
  • Source: Applied Biochemistry and Biotechnology
  • Volume: 129
  • Issue: 1/3
  • Year: 2006
  • Summary: The National Energy Modeling System (NEMS) is used by the Energy Information Administration (EIA) to forecast US energy production, consumption, and price trends for a 25-yr-time horizon. Biomass is one of the technologies within NEMS, which plays a key role in several scenarios. An endogenously determined biomass supply schedule is used to derive the price-quantity relationship of biomass. There are four components to the NEMS biomass supply schedule including: agricultural residues, energy crops, forestry residues, and urban wood waste/mill residues. The EIA's Annual Energy Outlook 2005 includes updated estimates of the agricultural residue portion of the biomass supply schedule. The changes from previous agricultural residue supply estimates include: revised assumptions concerning corn stover and wheat straw residue availabilities, inclusion of non-corn and non-wheat agricultural residues (such as barley, rice straw, and sugarcane bagasse), and the implementation of assumptions concerning increases in no-till farming. This article discusses the impact of these changes on the supply schedule.
  • Authors:
    • Mohamed, A. E. M.
    • Arab, Y. A.
    • El-Shehaby, A. I.
  • Source: Egyptian Journal of Agricultural Research
  • Volume: 84
  • Issue: 1
  • Year: 2006
  • Summary: Growing some summer crops - preceding garlic - in heavily infested potted soil significantly reduced white rot disease (Sclerotium cepivorum) of garlic. Reductions in disease incidence obtained with sugarcane, roquette [ Eruca vesicaria] and sorghum as intercrops were 80.0, 73.3 and 66.7% of the control treatment, respectively. Reductions in disease incidence obtained with maize, squash, pepper, soyabean, cotton, sesame, cowpea and roselle ranged between 53.3 and 40.0%. Cauliflower, lucerne, broad bean, nigella, Egyptian clover, coriander and roquette grown in pots, as winter crops preceding garlic, exhibited 46.7-26.7% reduction in white rot disease. Intercropping cauliflower, coriander and roquette with garlic reduced the disease by 46.0-53.8%. Seedling root exudates of cauliflower, coriander and sorghum significantly reduced mycelial growth of S. cepivorum on PDA plates more than did radish and sugarcane. Cauliflower exhibited the highest reduction in mycelial growth, followed by sorghum and coriander. Ascending rates of cauliflower root exudates resulted in a higher reduction in fungus growth. Counts of fungi were significantly higher in soil of sorghum and roquette compared with sugarcane and coriander, while coriander rhizosphere yielded the highest density of fungi. Actinomycetes were detected in the rhizosphere at a highest count with coriander but were completely absent in the soil. Bacteria, in contrast, existed only in the soil where actinomycetes were completely absent. The highest count of bacteria was detected in sorghum soil. Actinomycetes inhabited soil only while bacteria and fungi existed in soil and rhizosphere of cauliflower, radish and garlic intercropped with the two crops. Cauliflower significantly increased counts of fungi and bacteria in rhizosphere when intercropped with garlic compared with those detected with garlic alone. Some recommendations are made.
  • Authors:
    • Age Pedersen, C.
  • Source: Review of agricultural experiments 2006. Trials and research in the agronomy sector. Oversigt over Landsfors<o>gene 2006. Fors<o>g og unders<o>gelser i de land<o>konomiske foreninger.
  • Year: 2006
  • Summary: The organization and aims of the 'Landsforsgene', the collective name for the body that coordinates agricultural experiments in Denmark, are described. The growing season 2005-2006 in Denmark was characterized by long periods of severe drought in summer that resulted in lower crop yields, although the economic effect was mitigated to some extent by higher prices. Separate sections of the review deal with winter barley, winter rye, triticale, winter wheat, spring barley, oats, spring wheat, various seed crops, field seeds, winter rape, manures and calcium treatments, growing techniques, organic farming, potatoes, sugar beet, grass and green fodder crops, maize, plant breeding, general information on experimental design and aims, and a list of authors.
  • Authors:
    • Villenave, C.
    • Girardin, C.
    • Blanchart, E.
    • Azontonde, A.
    • Barthes, B.
    • Oliver, R.
    • Feller, C.
  • Source: Soil Erosion and Carbon Dynamics
  • Year: 2006
  • Summary: Field experiment was conducted from 1988 to 1999 at an experimental farm at Agonkanmey, near Cotonou in southern Benin, to study the effect of relay-cropping maize through Mucuna pruriens (var. utilis). The relay-cropping system was compared with traditional maize cropping system without any input, and with a maize cropping system with mineral fertilizers (NPK). Special attention was given on the changes in soil C during the period of the experiment in relation to residue biomass C returned to the soil, runoff and soil erosion losses, and loss of C with erosion. The soils are classified as sandy loam Typic Kandiustult. The general properties of these soils are given. For this soil type, relay cropping of maize and mucuna was very effective in enhancing C sequestration: change in Ct (total C content) stock for 0 to 40 cm depth was 1.3 t C/ha per year over the 12-year period of the experiment, ranging among the highest rates recorded for the eco-region. This increase resulted first from the high amount of residue biomass provided by mucuna, which amounted to 10 t DM/ha per year (83% aboveground). Mucuna residues, supplying the soil with N, also favoured the production of maize biomass, and total mucuna plus maize residue biomass returned to the soil was approximately 20 t/ha per year. In contrast, non-fertilized and fertilized continuous maize cultivation resulted in -0.2 and 0.2 t C/ha per year change in Ct stock for 0 to 40 cm depth, respectively. Total residue biomass was 8 and 13 t/ha per year, including 77 and 29% by weeds, respectively. Thick mulch produced by mucuna decreased losses by runoff and erosion, which were 0.28, 0.12 and 0.08 mm/mm and 34.0, 9.0 and 3.0 t/ha per year in unfertilized, fertilized with NPK and mucuna treatments, respectively. Eroded C was estimated at 0.3, 0.1 and 1.0 t C/ha per year in unfertilized, fertilized with NPK and mucuna treatments, respectively. Through its benefits on soil organic matter management, weed suppression and erosion control, cropping systems including a legume crop may have an adverse impact from a global change standpoint.
  • Authors:
    • Yang, H. S.
    • Amos, B.
    • Burba, G. G.
    • Suyker, A. E.
    • Arkebauer, T. J.
    • Knops, J. M.
    • Walters, D. T.
    • Cassman, K. G.
    • Dobermann, A.
    • Verma, S. B.
    • Ginting, D.
    • Hubbard, K. G.
    • Gitelson, A. A.
    • Walter-Shea, E. A.
  • Source: Agricultural and Forest Meteorology
  • Volume: 131
  • Issue: 1-2
  • Year: 2005
  • Summary: Carbon dioxide exchange was quantified in maize ( Zea mays)-soybean ( Glycine max) agroecosystems employing year-round tower eddy covariance flux systems and measurements of soil C stocks, CO 2 fluxes from the soil surface, plant biomass, and litter decomposition. Measurements were made in 3 cropping systems: (a) irrigated continuous maize; (b) irrigated maize-soybean rotation; and (c) rainfed maize-soybean rotation during 2001-2004. The study was conducted at the University of Nebraska Agricultural Research and Development Centre near Mead, Nebraska, USA. Because of a variable cropping history, all 3 sites were uniformly tilled by disking prior to initiation of the study. Since then, all sites are under no-till, and crop and soil management follow best management practices prescribed for production-scale systems. Cumulative daily gain of C by the crops (from planting to physiological maturity), determined from the measured eddy covariance CO 2 fluxes and estimated heterotrophic respiration, compared well with the measured total above and belowground biomass. Two contrasting features of maize and soyabean CO 2 exchange are notable. The value of integrated gross primary productivity (GPP) for both irrigated and rainfed maize over the growing season was substantially larger (ca. 2:1 ratio) than that for soyabean. Also, soyabean lost a larger portion (0.80-0.85) of GPP as ecosystem respiration (due, in part, to the large amount of maize residue from the previous year), as compared to maize (0.55-0.65). Therefore, the seasonally integrated net ecosystem production (NEP) in maize was larger by a 4:1 ratio (approximately), as compared to soyabean. Enhanced soil moisture conditions in the irrigated maize and soyabean fields caused an increase in ecosystem respiration, thus eliminating any advantage of increased GPP and giving about the same values for the growing season NEP as the rainfed fields. On an annual basis, the NEP of irrigated continuous maize was 517, 424, and 381 g C m -2 year -1, respectively, during the 3 years of our study. In rainfed maize, the annual NEP was 510 and 397 g C m -2 year -1 in years 1 and 3, respectively. The annual NEP in the irrigated and rainfed soyabean fields were in the range of -18 to -48 g C m -2. Accounting for the grain C removed during harvest and the CO 2 released from irrigation water, our tower eddy covariance flux data over the first 3 years suggest that, at this time: (a) the rainfed maize-soybean rotation system is C neutral; (b) the irrigated continuous maize is nearly C neutral or a slight source of C; and (c) the irrigated maize-soybean rotation is a moderate source of C. Direct measurement of soil C stocks could not detect a statistically significant change in soil organic carbon during the first 3 years of no-till farming in these 3 cropping systems.
  • Authors:
    • Atwood,J. D.
    • Izaurralde, R. C.
    • Williams, J. R.
    • He, X.
    • Wang, X.
  • Source: Transactions of the ASAE
  • Volume: 48
  • Issue: 3
  • Year: 2005
  • Summary: Modeling biophysical processes is a complex endeavor because of large data requirements and uncertainty in model parameters. Model predictions should incorporate, when possible, analyses of their uncertainty and sensitivity. The study incorporated uncertainty analysis on EPIC (Environmental Policy Impact Calculator) predictions of corn (Zea mays L.) yield and soil organic carbon (SOC) using generalized likelihood uncertainty estimation (GLUE). An automatic parameter optimization procedure was developed at the conclusion of sensitivity analysis, which was conducted using the extended Fourier amplitude sensitivity test (FAST). The analyses were based on an experimental field under 34-year continuous corn with five N treatments at the Arlington Agricultural Research Station in Wisconsin. The observed average annual yields per treatment during 1958 to 1991 fell well within the 90% confidence interval (CI) of the annually averaged predictions. The width of the 90% CI bands of predicted average yields ranged from 0.31 to 1.6 Mg ha-1. The predicted means per treatment over simulations were 3.26 to 6.37 Mg ha-1, with observations from 3.28 to 6.4 Mg ha-1. The predicted means of yearly yield over simulations were 1.77 to 9.22 Mg ha-1, with observations from 1.35 to 10.22 Mg ha-1. The 90% confidence width for predicted yearly SOC in the top 0.2 m soil was 285 to 625 g C m-2, while predicted means were 5122 to 6564 g C m-2 and observations were 5645 to 6733 g C m-2. The optimal parameter set identified through the automatic parameter optimization procedure gave an R2 of 0.96 for average corn yield predictions and 0.89 for yearly SOC. EPIC was dependable, from a statistical point of view, in predicting average yield and SOC dynamics.
  • Authors:
    • Kelly, K.
    • Baigent, R.
    • Eckard, R.
    • Weeks, I.
    • Leuning, R.
    • Phillips, F.
    • Barker-Reid, F.
    • Gates, W.
    • Grace, P.
    • Galbally, I.
    • Meyer, M.
    • Bentley, S.
  • Source: Environmental Sciences
  • Volume: 2
  • Issue: 2-3
  • Year: 2005