• Authors:
    • Prado A., R. del
    • Diaz S., J.
    • Espinoza N., N.
  • Source: XVII Congreso de la Asociación Latinoamericana de Malezas (ALAM) I Congreso Iberoamericano de Ciencia de las Malezas, IV Congreso Nacional de Ciencia de Malezas, Matanzas, Cuba, 8 al 11 de noviembre del 2005, pp. 326
  • Year: 2005
  • Summary: Eight biotypes of herbicide-resistant weeds have been described in Chile. All belong to grass weeds, specifically wild oat ( Avena fatua), ryegrass ( Lolium rigidum), Italian ryegrass ( L. multiflorum) and crested dogtailgrass ( Cynosurus echinatus), which are the most common in the main wheat, barley, oats, lupin and canola producing area (36degreesS to 39degreesS). The biotypes have shown resistance to ACCasa, ALS and EPSP inhibitors. Most biotypes have appeared in farm fields subjected to intensive land use, with annual crops, with a trend to wheat monoculture in some cases, and with intense use of no-till and herbicides with similar mode of action. Herbicides most frequently used have been glyphosate (EPSP), diclofop-methyl and clodinafop-propargyl (ACCasa). Cross-resistance to ACCasa was found in some biotypes of wild oat and ryegrass, with greater resistance to aryloxyphenoxypropionates than to cyclohexanediones. All ACCasaresistant biotypes were susceptible to iodosulfuron and flucarbazone Na (ALS). These two herbicides are recommended for wheat and began to be used just recently in the country. Two biotypes of Italian ryegrass were found resistant to glyphosate. One of these biotypes showed, in addition, resistance to ALS; that is to say, showed multiple resistance. Also the crested dogtailgrass biotype showed multiple resistance to ACCasa and ALS.
  • Authors:
    • Australia, Wagga Wagga Agricultural Institute
  • Source: Cultivar X herbicide screening: 2005 results
  • Year: 2005
  • Summary: The results are included on this CD-ROM for herbicide trials involving wheat, barley, oats, triticale, rape, lupin and field pea. Field trials were sprayed with the recommended application rate (1xR) and twice the rate (2xR). The high rate establishes the safety margin of the herbicide and confirms the differences in tolerances between the cultivars used. New varieties and advanced lines from various breeding programmes were tested at the x2 rate of only a subset of herbicides. Grain yield of sprayed versus unsprayed plots is used as a measure of crop tolerance of the herbicide. The results of not just 2005 trials are included but also those from 2002, 2003 and 2004 are also included on the CD-ROM together with photographs from the trials.
  • Authors:
    • Linden, D. R.
    • Voorhees, W. B.
    • Hatfield, J. L.
    • Johnson, J. M. F.
    • Wilhelm, W. W.
  • Source: Agronomy Journal
  • Volume: 96
  • Issue: 1
  • Year: 2004
  • Summary: Society is facing three related issues: overreliance on imported fuel, increasing levels of greenhouse gases in the atmosphere, and producing sufficient food for a growing world population. The U.S. Department of Energy and private enterprise are developing technology necessary to use high-cellulose feedstock, such as crop residues, for ethanol production. Corn (Zea mays L.) residue can provide about 1.7 times more C than barley (Hordeum vulgare L.), oat (Avena sativa L.), sorghum [Sorghum bicolor (L.) Moench], soybean [Glycine max (L.) Merr.], sunflower (Helianthus annuus L.), and wheat (Triticum aestivum L.) residues based on production levels. Removal of crop residue from the field must be balanced against impacting the environment (soil erosion), maintaining soil organic matter levels, and preserving or enhancing productivity. Our objective is to summarize published works for potential impacts of wide-scale, corn stover collection on corn production capacity in Corn Belt soils. We address the issue of crop yield (sustainability) and related soil processes directly. However, scarcity of data requires us to deal with the issue of greenhouse gases indirectly and by inference. All ramifications of new management practices and crop uses must be explored and evaluated fully before an industry is established. Our conclusion is that within limits, corn stover can be harvested for ethanol production to provide a renewable, domestic source of energy that reduces greenhouse gases. Recommendation for removal rates will vary based on regional yield, climatic conditions, and cultural practices. Agronomists are challenged to develop a procedure (tool) for recommending maximum permissible removal rates that ensure sustained soil productivity.
  • Authors:
    • NASDA
  • Year: 2004
  • Authors:
    • Dale, B. E.
    • Kim, S.
  • Source: Biomass and Bioenergy
  • Volume: 26
  • Issue: 4
  • Year: 2004
  • Summary: The global annual potential bioethanol production from the major crops, corn, barley, oat, rice, wheat, sorghum, and sugar cane, is estimated. To avoid conflicts between human food use and industrial use of crops, only the wasted crop, which is defined as crop lost in distribution, is considered as feedstock. Lignocellulosic biomass such as crop residues and sugar cane bagasse are included in feedstock for producing bioethanol as well. There are about 73:9 Tg of dry wasted crops in the world that could potentially produce 49:1 GL year-1 of bioethanol. About 1:5 Pg year-1 of dry lignocellulosic biomass from these seven crops is also available for conversion to bioethanol. Lignocellulosic biomass could produce up to 442 GL year-1 of bioethanol. Thus, the total potential bioethanol production from crop residues and wasted crops is 491 GL year-1, about 16 times higher than the current world ethanol production. The potential bioethanol production could replace 353 GL of gasoline (32% of the global gasoline consumption) when bioethanol is used in E85 fuel for a midsize passenger vehicle. Furthermore, lignin-rich fermentation residue, which is the coproduct of bioethanol made from crop residues and sugar cane bagasse, can potentially generate both 458 TWh of electricity (about 3.6% of world electricity production) and 2:6EJ of steam. Asia is the largest potential producer of bioethanol from crop residues and wasted crops, and could produce up to 291 GL year -1 of bioethanol. Rice straw, wheat straw, and corn stover are the most favorable bioethanol feedstocks in Asia. The next highest potential region is Europe (69:2 GL ofbioethanol), in which most bioethanol comes from wheat straw. Corn stover is the main feedstock in North America, from which about 38:4 GL year -1 of bioethanol can potentially be produced. Globally rice straw can produce 205 GL of bioethanol, which is the largest amount from single biomass feedstock. The next highest potential feedstock is wheat straw, which can produce 104 GL of bioethanol. This paper is intended to give some perspective on the size ofthe bioethanol feedstock resource, globally and by region, and to summarize relevant data that we believe others will 0nd useful, for example, those who are interested in producing biobased products such as lactic acid, rather than ethanol, from crops and wastes. The paper does not attempt to indicate how much, if any, of this waste material could actually be converted to bioethanol.
  • Authors:
    • Palm, C.
    • King, J.
    • Verchot, L.
    • Wassmann, R.
    • Mosier, A.
  • Source: Environment, Development and Sustainability
  • Volume: 6
  • Issue: 1-2
  • Year: 2004
  • Summary: Tropical soils are important sources and sinks of atmospheric methane (CH4) and major sources of oxides of nitrogen gases, nitrous oxide (N2O) and NOx (NO+NO2). These gases are present in the atmosphere in trace amounts and are important to atmospheric chemistry and earth's radiative balance. Although nitric oxide (NO) does not directly contribute to the greenhouse effect by absorbing infrared radiation, it contributes to climate forcing through its role in photochemistry of hydroxyl radicals and ozone (O3) and plays a key role in air quality issues. Agricultural soils are a primary source of anthropogenic trace gas emissions, and the tropics and subtropics contribute greatly, particularly since 51% of world soils are in these climate zones. The soil microbial processes responsible for the production and consumption of CH4 and production of N-oxides are the same in all parts of the globe, regardless of climate. Because of the ubiquitous nature of the basic enzymatic processes in the soil, the biological processes responsible for the production of NO, N2O and CH4, nitrification/denitrification and methanogenesis/methanotropy are discussed in general terms. Soil water content and nutrient availability are key controls for production, consumption and emission of these gases. Intensive studies of CH4 exchange in rice production systems made during the past decade reveal new insight. At the same time, there have been relatively few measurements of CH4, N2O or NOx fluxes in upland tropical crop production systems. There are even fewer studies in which simultaneous measurements of these gases are reported. Such measurements are necessary for determining total greenhouse gas emission budgets. While intensive agricultural systems are important global sources of N2O and CH4 recent studies are revealing that the impact of tropical land use change on trace gas emissions is not as great as first reports suggested. It is becoming apparent that although conversion of forests to grazing lands initially induces higher N-oxide emissions than observed from the primary forest, within a few years emissions of NO and N2O generally fall below those from the primary forest. On the other hand, CH4 oxidation is typically greatly reduced and grazing lands may even become net sources in situations where soil compaction from cattle traffic limits gas diffusion. Establishment of tree-based systems following slash-and-burn agriculture enhances N2O and NO emissions during and immediately following burning. These emissions soon decline to rates similar to those observed in secondary forest while CH4 consumption rates are slightly reduced. Conversion to intensive cropping systems, on the other hand, results in significant increases in N2O emissions, a loss of the CH4 sink, and a substantial increase in the global warming potential compared to the forest and tree-based systems. The increasing intensification of crop production in the tropics, in which N fertilization must increase for many crops to sustain production, will most certainly increase N-oxide emissions. The increase, however, may be on the same order as that expected in temperate crop production, thus smaller than some have predicted. In addition, increased attention to management of fertilizer and water may reduce trace gas emissions and simultaneously increase fertilizer use efficiency.
  • Authors:
    • Holland, J. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 103
  • Issue: 1
  • Year: 2004
  • Summary: Conservation tillage (CT) is practised on 45 million ha world-wide, predominantly in North and South America but its uptake is also increasing in South Africa, Australia and other semi-arid areas of the world. It is primarily used as a means to protect soils from erosion and compaction, to conserve moisture and reduce production costs. In Europe, the area cultivated using minimum tillage is increasing primarily in an effort to reduce production costs, but also as a way of preventing soil erosion and retain soil moisture. A large proportion (16%) of Europe's cultivated land is also prone to soil degradation but farmers and governments are being slow to recognise and address the problem, despite the widespread environmental problems that can occur when soils become degraded. Conservation tillage can improve soil structure and stability thereby facilitating better drainage and water holding capacity that reduces the extremes of water logging and drought. These improvements to soil structure also reduce the risk of runoff and pollution of surface waters with sediment, pesticides and nutrients. Reducing the intensity of soil cultivation lowers energy consumption and the emission of carbon dioxide, while carbon sequestration is raised though the increase in soil organic matter (SOM). Under conservation tillage, a richer soil biota develops that can improve nutrient recycling and this may also help combat crop pests and diseases. The greater availability of crop residues and weed seeds improves food supplies for insects, birds and small mammals. All these aspects are reviewed but detailed information on the environmental benefits of conservation tillage is sparse and disparate from European studies. No detailed studies have been conducted at the catchment scale in Europe, therefore some findings must be treated with caution until they can be verified at a larger scale and for a greater range of climatic, cropping and soil conditions. (C) 2004 Elsevier B.V. All rights reserved.
  • Authors:
    • Kreye, H.
  • Source: Bulletin OILB/SROP
  • Volume: 27
  • Issue: 10
  • Year: 2004
  • Summary: In a long-term field trial, the effects of three different tillage systems on harmful organisms and yield were investigated. The focus was on fungal diseases, weeds and slugs. With the ploughing system as the standard, a non-inversion/conservation tillage and a direct drilling/no till system were compared with one another. The crop rotation oilseed rape-wheat-barley, which was established in 1995, was reconverted into a crop rotation oilseed rape-wheat-wheat in 1998 due to problems with volunteer wheat in the following barley in the two ploughless tillage systems. The occurrence of Phoma root-collar and stem disease, the most important in Germany, was not affected in comparison over the years by the intensity of the cultivation. For Sclerotinia stem rot, a correlation could only be determined with the tillage systems in one year of the trial series. The infection became more severe with decreasing intensity of soil cultivation. Whether this result can be reproduced in future growing seasons remains to be seen. Effects on the incidence of Verticillium longisporum could not be determined. Other diseases arose only sporadically at very low levels. However, in comparison, the occurrence of weeds was affected significantly. The amount of grass weed species ( Alopecurus myosuroides, Apera spica-venti, volunteer barley) increased in the systems without ploughing. The effect on dicotyledonous weed species was dependent on the particular species. In individual years, heavy slug damage could be correlated with direct drilling system.
  • Authors:
    • Merrill, S.
    • Lares, M.
    • Tanaka, D.
    • Krupinsky, J.
  • Source: Agronomy Journal
  • Volume: 96
  • Issue: 1
  • Year: 2004
  • Summary: Crop diversification and crop sequencing can influence plant disease risk in cropping systems. The objective of this research was to determine the effect of 10 previous crops on leaf spot diseases of barley ( Hordeum vulgare L.) and hard red spring wheat ( Triticum aestivum L.). Barley and spring wheat were direct-seeded (no till) in the crop residue of 10 crops {barley, canola ( Brassica napus L.), crambe ( Crambe abyssinica Hochst. ex R.E. Fr.), dry bean ( Phaseolus vulgaris L.), dry pea ( Pisum sativum L.), flax ( Linum usitatissimum L.), safflower ( Carthamus tinctorius L.), soybean [ Glycine max (L.) Merr.], sunflower ( Helianthus annuus L.), and spring wheat}. Barley was evaluated for leaf spot diseases 15 times over 2 yr. Results indicate that risk for leaf spot disease on barley would be lower following wheat, crambe, canola and dry pea compared with the barley-after-barley treatment. Although barley yields were similar across all treatments one year, differences were detected in another year with the barley-after-barley treatment having the lowest yield. Spring wheat was evaluated for leaf spot diseases 22 times over 2 yr. Differences among treatments were more detectable in earlier evaluations, indicating a greater influence of crop residue and carryover of inoculum early in the season compared with later. The risk for leaf spot disease was lower when wheat was grown after canola, barley, crambe, and flax than when grown after the other crops. Although wheat yields were similar across all treatments one year, differences were detected in another year with the wheat-after-wheat treatment having the lowest yield.
  • Authors:
    • Correa, R.
    • Wilkins, D.
    • Siemens, M.
  • Source: Transactions of the ASAE
  • Volume: 47
  • Issue: 2
  • Year: 2004
  • Summary: Adoption of conservation tillage in the Pacific Northwest lags that of the U.S. in part due to the lack of reliable seeding equipment for planting into the high residue densities encountered in this region. To overcome this problem, a drill attachment was developed to manage heavy residue next to the furrow opening tines of hoe-type no-till drills. The U.S. patented device consists of a fingered rubber wheel, a rubber inner ring, and a spring-loaded arm that pivots about vertical and horizontal axes. The performance of the device was evaluated in terms of stand establishment and yield in Oregon and Washington. Test site locations varied significantly in the amount and condition of crop residue and were planted to a variety of different crops. As compared to the standard no-till drill without the attachment, use of the residue management wheel was found to increase the stand establishment of small seeded crops such as canola and mustard by over 40% and large seeded crops such as wheat and barley by approximately 17%. Increases in stand establishment were attributed to fewer piles of residue covering the seed row. Use of the device also significantly increased crop yield by up to 12% in 8 of the 20 trials conducted (P≤0.10). Although the residue management wheel costs $300 per unit to fabricate, using the device may be economically feasible if it results in significant improvements in both stand establishment and yield.