• Authors:
    • Mosier, A. R.
    • Burke, I. C.
    • Kaye, J. P.
    • Guerschman, J. P.
  • Source: Ecological Applications
  • Volume: 14
  • Issue: 4
  • Year: 2004
  • Summary: Land-use change is an important driver of soil-atmosphere gas exchange, but current greenhouse-gas budgets lack data from urban lands. Field comparisons of urban and non-urban ecosystems are required to predict the consequences of global urban-land expansion for greenhouse-gas budgets. In a rapidly urbanizing region of the U.S. Great Plains, we measured soil-atmosphere exchange of methane (CH 4) and nitrous oxide (N 2O) for one year in replicated ( n=3) urban lawn, native shortgrass steppe, dryland wheat-fallow, and flood-irrigated corn ecosystems. All soils were net sinks for atmospheric CH 4, but uptake by urban, corn, and wheat-fallow soils was half that of native grasslands (-0.300.04 g C.m -2.yr -1 [mean1 Se]). Urban (0.240.03 g N.m -2.yr -1) and corn (0.200.02 g N.m -2.yr -1) soils emitted 10 times more N 2O to the atmosphere than native grassland and wheat-fallow soils. Using remotely sensed land-cover data we calculated an upper bound for the contribution of lawns to regional soil-atmosphere gas fluxes. Urban lawns occupied 6.4% of a 1578-km 2 study region, but contribute up to 5% and 30% of the regional soil CH 4 consumption and N 2O emission, respectively, from land-use types that we sampled. Lawns that cover small portions of the landscape may contribute significantly to regional soil-atmosphere gas exchange.
  • Authors:
    • Skinner, D. Z.
    • Liang, G. H.
  • Year: 2004
  • Summary: This book contains chapters on: genetic transformation; mechanisms of transgene locus formation; gene stacking through site-specific integration; transgenics of plant hormones and their potential application in horticultural crops; avidin in transgenic maize; genetic engineering protocols and use to enhance stress tolerance in wheat; development and utilization of transformation in Medicago spp.; sorghum transformation for resistance to fungal pathogens and drought; current progress and future prospects in rice transformation; successes and challenges in cotton transformation; progress in transforming the recalcitrant soyabean; progress in vegetable crop transformation and future prospects and challenges; genetic transformation of turfgrass; and risks associated with genetically engineered crops.
  • Authors:
    • Reddy, G. B.
    • Brock, B.
    • Naderman, G.
    • Raczkowski, C. W.
  • Source: Proceedings of the 26th Southern Conservation Tillage Conference for Sustainable Agriculture 8-9 June, 2004, Raleigh, North Carolina
  • Year: 2004
  • Summary: This study reports the results of sampling soil within a field experiment at CEFS, the Cherry Farm, Goldsboro, North Carolina. The experiment tested effects of six years of conservation tillage with cover crops, contrasted with chisel plow/disk tillage without cover crops, under three crop rotations. In April, 2003 two sets of undisturbed core samples were collected from six mapped soil areas, at depth increments of 0-2 and 2-5 inches, replicated four times. One set was used for soil bulk density; the other provided soil carbon and total nitrogen contents. The study found strong and consistent inverse correlations between soil carbon content and bulk density. Under conservation tillage the surface two inches generally sustained suitable density for root activities. However, at 2-5 inches density approached or exceeded 1.6 g cm-3. Given the textures involved, this density likely would affect root growth, especially under non-ideal, wet/cool or dry/hard conditions. This would be especially important for crop establishment within this prime rooting zone. This low carbon/high-density problem was less likely for soils containing the influences of more silt with less sand. It was greater when corn, peanut and cotton were grown compared to producing soyabean or wheat/soybean with corn. This study revealed increased carbon sequestration from the conservation tillage systems used, along with increased total N content in the surface five inches of soil. Conservation tillage as practiced helped to reduce the "greenhouse effect" and lessened N leaching losses, holding more of these elements within the topsoil.
  • Authors:
    • O'Connell, P. J.
    • Allard, J. L.
  • Source: Weed management: balancing people, planet, profit. 14th Australian Weeds Conference, Wagga Wagga, New South Wales, Australia, 6-9 September 2004: papers and proceedings 2004
  • Year: 2004
  • Summary: Australian winter broadacre crops have been planted on 19.4 million ha on average, over the five years 1999-2003. The cropped area is dominated by cereals and in particular wheat. Annual ryegrass (ARG, Lolium rigidum) is the most widespread, difficult to control and important weed of Australian winter broadacre farming systems, and is arguably the greatest threat to sustainability of these systems. It was calculated that it infests ~6 million ha. Syngenta's analyses of herbicide sales suggest that the area treated for annual ryegrass could be as high as 8 million ha. Herbicide sales have been used to estimate the area treated for ARG control. This analysis focuses on herbicides for which there is not yet widespread ARG resistance. Grain producers are heavily dependant on two groups of herbicides. Group M (glyphosate) is applied as a non-selective burn-down treatment prior to planting and is applied to as much as 25 million ha (applied up to 132% of the winter crop area). The Group D herbicides, especially trifluralin, are used for pre-emergent weed control on nearly 7 million ha, 36% of the cropped area, up from 25% in 2001. There is circumstantial evidence that Group D herbicides are mostly applied for the management of ARG, and there is a high risk of over-use. Minimum- and no-tillage are used on 76% of the cropped area, while burning as a weed control technique (hot burn) is used on just over 10% of the area. In view of the current willingness of grain growers to rely heavily upon herbicides for weed control, a greater burden is placed on ensuring herbicide rotational strategies are carefully thought through and implemented. This has resulted in extension of double-knockdown techniques with Spray.Seed to reduce the likelihood of glyphosate resistant ARG in reduced tillage environments. A similar education programme needs to be directed towards Group D herbicides and alternatives promoted. Group K herbicides, including S-metolachlor (Dual Gold), are potential alternatives. Group K herbicides are generally well-tolerated by barley, oats, legumes and canola and can be used at higher rates in these crops. Wheat is less tolerant at the rates required to manage ARG effectively. Rotating to Group K herbicides outside wheat is proposed. The grains industry could evaluate the model the Australian cotton industry has established for the very successful management of insecticide resistance. A better way to manage herbicide use and rotation needs to be found, particularly as fewer new active ingredients are expected to be developed than in the past.
  • Authors:
    • Philip, H.
    • Woods, S.
    • Weiss, R. M.
    • Olfert, O.
    • Dosdall, L.
  • Source: The Canadian Entomologist
  • Volume: 136
  • Issue: 2
  • Year: 2004
  • Summary: Cereal leaf beetle, Oulema melanopus L., is an invasive pest insect of small grain cereal crops, particularly oat, wheat, and barley. The first report of cereal leaf beetle populations in North America came from Michigan in 1962. Surveys indicate that populations have become established throughout eastern North America from Ontario to Alabama and in northwestern North America from Utah to southern British Columbia. The establishment of O. melanopus in western North America has raised concern that its presence is a potential risk to the Canadian cereal industry, especially in the prairie ecozone of western Canada, where up to 10 million hectares of cereal crops are grown annually. Field surveys to date have indicated that O. melanopus has not yet become established in this region. A CLIMEX(TM)model for O. melanopus in North America was developed, based on climate and ecological parameters, and validated with actual distribution records. The actual distribution of O. melanopus in eastern North America matched the predicted distribution well. The model predicts that, once introduced, O. melanopus would readily survive in the cereal-growing areas of western Canada and present a significant risk to cereal production. The potential for establishment of O. melanopus in the prairie ecozone of western Canada substantiates the efforts by regulatory agencies to prevent accidental introduction of this pest species.
  • Authors:
    • UK, HGCA
  • Source: HGCA recommended list 2004/05 for cereals and oilseeds
  • Year: 2004
  • Summary: Descriptions are provided for cultivars of cereals (winter, late autumn and spring wheat, winter and spring barley, winter rye, winter triticale, and winter and spring oat) and oilseeds (winter and spring oilseed rape and spring linseed) recommended for cultivation in the UK in 2004/05.
  • Authors:
    • Zakharenko, V. A.
  • Source: Zashchita i Karantin Rastenii
  • Issue: 12
  • Year: 2004
  • Summary: Wild oat (Avena fatua) is widely spread in cereals, particularly wheat, barley and oat, in many regions of Russia, causing up to 40% losses of crops, and a decrease of quality of seed material, and food and feed grains. Investigations carried out in the Orlov region, European Russia, revealed significant infestations of agricultural crops, particularly winter and spring wheat, and pea, with wild oat. Data are tabulated on herbicides effective against Poaceae weeds including A. fatua in sugarbeet, sunflower, soyabean, rape, potato and vegetable crops. Strategies for prevention and control of A. fatua are discussed. Data are also tabulated on herbicides showing activity against Poaceae and dicotyledonous weeds, as well as A. sativa in maize, sugarbeet, sunflower, soyabean, rape, potato and vegetable crops.
  • Authors:
    • Acker, R. van
    • Boyd, N.
  • Source: Weed Science
  • Volume: 52
  • Issue: 4
  • Year: 2004
  • Summary: Laboratory experiments were conducted to determine the effects of oxygen concentration (21, 10, 5 and 2.5%), exposure to light, and osmotic potential on the germination of wheat, canola [rape] and various weed species, i.e. barnyardgrass ( Echinochloa crus-galli), catchweed bedstraw ( Galium aparine), curly dock ( Rumex crispus), dandelion ( Taraxacum officinale), foxtail barley ( Hordeum jubatum), green foxtail ( Setaria viridis), perennial sowthistle ( Sonchus arvensis), wild mustard ( Brassica kaber), wild oat ( Avena fatua) and field pennycress ( Thlaspi arvense). Germination of most species increased as osmotic potential was increased. Seed germination for some species like barnyardgrass was inhibited by the combination of exposure to normoxic (21% oxygen) conditions and light. This combination of conditions may function as a signal to prevent soil surface germination. Wild mustard germination increased with increasing oxygen concentration when seeds were not exposed to light, whereas green foxtail germination was relatively insensitive to oxygen concentration. Wild oat germination increased with increasing osmotic potential, and osmotic potential had a greater influence when the seeds were exposed to light. Dandelion, foxtail barley, curly dock and perennial sowthistle germination was affected more by osmotic potential and light exposure than by oxygen concentration. A better understanding of the mechanisms of depth detection for specific species will lead to a better understanding of their recruitment biology. This information may help model the potential for invasion and proliferation of each species as well as devise improved management strategies.
  • Authors:
    • Bunce, J. A.
  • Source: Oecologia
  • Volume: 140
  • Issue: 1
  • Year: 2004
  • Summary: Reductions in leaf stomatal conductance with rising atmospheric carbon dioxide concentration ([CO 2]) could reduce water use by vegetation and potentially alter climate. Crop plants have among the largest reductions in stomatal conductance at elevated [CO 2]. The relative reduction in stomatal conductance caused by a given increase in [CO 2] is often not constant within a day nor between days, but may vary considerably with light, temperature and humidity. Species also differ in response, with a doubling of [CO 2] reducing mean midday conductances by 50% in others. Elevated [CO 2] increases leaf area index throughout the growing season in some species. Simulations, and measurements in free air carbon dioxide enrichment systems both indicate that the relatively large reductions in stomatal conductance in crops would translate into reductions of
  • Authors:
    • Hrstkova, P.
    • Chloupek, O.
    • Schweigert, P.
  • Source: Field Crops Research
  • Volume: 85
  • Issue: 2-3
  • Year: 2004
  • Summary: Officially published data for the Czech Republic (CR) from 1920 to 2000 and for selected European countries (mostly from 1960 to 2000) were analysed. In the last 40 years, the yield of the five main crops was comparable with European Union (EU) for wheat, barley and rape, but lower for potato and sugar beet. The fastest yield growth was found for flax (2.15% per year), maize and wheat (1.61 and 1.53%), while growth was slower for hops and root crops and slowest for grassland hay (0.22%). The highest yield variation caused by individual years was for wine grapes (32.5%), poppy, edible legumes and flax (18.5-18.3%), while the lowest level of variation was for cereals, i.e. oats, barley, wheat, rye and hay from arable land (9.7-12.0%). For many crops, yield variation decreased over time. The most adaptable crops, whose yield increased most in fertile years, were flax, wheat, edible legumes, maize, rape and barley (regression coefficient of 1.76-1.24), while the lowest level of adaptability was shown by hops, sugar beet, hay from grassland and poppy (0.68-0.14). The higher the level of adaptability the higher the yield growth over the 75 years analysed. The differences in yield of the most commonly grown crops between the EU and the CR can be explained by the different levels of adaptability of the crops in the two regions. Of the five most commonly grown CR crops, wheat was the most adapted crop in 7 of the 10 European countries studied (without regard to other countries), and sugar beet was the least adapted in 6 countries, Within the 10 countries analysed (without regard for the adaptability of the crop in particular countries) wheat, rape and sugar beet were most adaptable in Spain; barley was most adaptable in Italy; and potato was most adaptable in Hungary. The crops in other countries showed more stability across years. Yields of these five crops in the 10 countries were correlated to each other, with only the yield of potato and sugar beet in the former Soviet Union and that of rape in United Kingdom not being influenced by general factors affecting other countries. The higher the yield of sugar beet in a country of the 10 evaluated, the higher was its adaptability in that country (r = 0.717*). Crop diversity in the CR decreased significantly over the period. Each year the percentage of the three most commonly grown crops increased by 0.41% (percentage of the five most commonly grown crops by 0.14%). The percentage of particular cereals on arable land (wheat 23.0%, barley 17.1%, rye 5.1%, oat 5.2%) and their yields were related to their response to fertilisation over the last 40 years. The average temperature increased significantly during the last 50 years, on average by 0.021 degreesC each year, but in the last 10 years by 0.087 degreesC each year. These climate changes were favourable for the most of the commonly grown crops (wheat, barley, rape, sugar beet, rye, maize and legumes), since the crops gave higher yields in warmer years that were accompanied by more hours of sunshine. The other crops were indifferent to climate changes. Fertilisers have been used in the CR to a greater extent since 1946/1947 (22 kg of nutrients per hectare) with maximum usage in 1985/1986 (273 kg ha(-1), including 105 kg N, 86 kg P and 82 kg K). The consumption rate of nutrients increased by 2.91 kg ha(-1) annually from 1918 to 2000, as found by the regression coefficient. One kilogram of nutrients (N + P + K) increased yields of cereals by 6.7-10.1 kg ha(-1) of grain, rape by 5.2, root crops by 26.1-37.8, hops and wine grapes by 2.0-2.6 kg ha(-1). Yield growth due to fertilisation varied from 9.1% (hay from arable land) up to 84.1% (hops) of the entire growth (=100%). The percentage in grain crops (cereals, grain legumes and rape) was 54.3 (maize)-69.8% (barley), and 63.3% on average in the eight crops. It was also similar in root crops, but only 13.4% for wine grape yields. The highest yield growth per 1 kg of nutrients from fertilisers was found in wheat, rape, sugar beet and potato at the level of application of 70-120 kg ha(-1) nutrients. The efficiency of applied nutrients was higher in years with average precipitation than in years with over-average precipitation, and much higher than in dry years. The yield growth for 1 kg nutrients in all grain crops was lowest in years with average temperature, and highest in most of the crops in years with low mean annual temperature. The estimated balance of nitrogen (applied nitrogen in fertilisers minus nitrogen utilised in harvested crops) was negative during 1947-1960, positive during 1970-1990, and slightly negative again from 1995 to 2000. The surplus of applied mineral nitrogen reached in the years of positive balance was 18.5-36.8 kg ha(-1). The impact of the weather was less than the influence of fertilisation. The dynamics of yield in Germany was studied by multiple regression analysis from 1946 to 1999. The annual increase of wheat yield was 50 kg ha(-1), and per kilogram of N-fertiliser by 10 kg ha(-1). The increase per year in the multiple regression was only 73% of the increase in the simple regression. Therefore, 27% of the increase was related to N-fertilisation (and also to other inputs). The corresponding figures were 25% for rye, 30% for rape, 36% for oats, 47% for potato and 66% for flax. No significant influence of N-fertiliser could be found for other crops. It is concluded that those crops exhibiting the highest increase in yield in the CR over the 75 years investigated were also the most adaptable to inter-annual variability in weather, cultivars grown and to cultivation technologies used. The least adapted crop across 10 European countries was sugar beet, for which adaptability was correlated to yield in the particular country. Among the factors studied, the high response to fertilisation was an important factor in the adaptability of particular crops over the 75 years studied. The adaptability of crops to inter-annual variation is therefore a very important trait for consideration by plant breeders. (C) 2003 Elsevier B.V. All rights reserved.