• Authors:
    • Kevan, P. G.
    • Belaoussoff, S.
    • Clements, D. R.
    • Murphy, S. D.
    • Swanton, C. J.
  • Source: Weed Science
  • Volume: 54
  • Issue: 1
  • Year: 2006
  • Summary: In a 6-yr study on four farms (36 fields) in Ontario, Canada, we tested the effects of tillage (moldboard, chisel plow, no tillage) and crop rotations (continuous corn, corn-soybean, corn-soybean-winter wheat) on emerged and seedbank weed species diversity and density Aside from the imposed experimental treatments, all other management was generally consistent among farms. Tillage had the largest effect on weed diversity and density. No tillage promoted the highest weed species diversity, chisel plow was intermediate, and moldboard plow resulted in the lowest species diversity. These results are consistent with ecological succession theory. The increase in weed species diversity resulted from 20 species being associated with no tillage systems, 15 of which were winter annuals, biennials, or perennials. Emerged weed density was affected only by tillage. Over 6 yr, seedbank declined in no-tillage systems from 41,000 to 8,000 seeds m(-3). Crop yields were not affected by tillage or crop rotation. In practical terms, reduced tillage in combination with a good crop rotation may reduce weed density and expenditures on weed management.
  • Authors:
    • Wojciak, H.
    • Adamiak, J.
    • Rychcik, B.
  • Source: Plant, Soil and Environment
  • Volume: 52
  • Issue: Special Issue
  • Year: 2006
  • Summary: A field experiment was conducted during 1992-2004 on Luvisols (formed from silty light loam) at the Experimental Station at Bacyny to investigate the response of the most important plants cultivated in Poland to monocultural cultivation. Twelve plant species were cultivated in crop rotations: (A) potato-oats-flax-winter rye-faba bean-winter triticale; (B) sugarbeet-maize-spring barley-pea-winter rape-winter wheat, and (C) each of the species in monocultures. The organic matter content in the soil plough layer (0-250 mm) in 1992, 1998 and 2004 is presented. Fractionation of humus was carried out with the Duchaufour and Jacquin method. Under the conditions of the crop rotations, organic matter content slightly increased; similar tendencies were observed in most monoculture fields. The lowest content of organic C was recorded under the conditions of continuous cultivation of pea, maize and faba bean. Humins and humus compounds (extraction II and III) had a dominant share among the determined fractions. Humic acids prevailed over fulvic acids in the crop rotation cultivations and in the most monoculture fields. However, the prevalence of fulvic acids was found under the conditions of continuous cultivation of sugarbeet, potato and winter rye.
  • Authors:
    • Harker, K. N.
    • Beckie, H. J.
    • Blackshaw, R. E.
    • Upadhyay, B. M.
    • Smith, E. G.
    • Clayton, G. W.
  • Source: Canadian Journal of Plant Science
  • Volume: 86
  • Issue: 4
  • Year: 2006
  • Summary: Integrated weed management (IWM) systems that combine seeding date, seeding rate, herbicide rate, and timing of nitrogen (N) fertilizer application were assessed for their economic performance in the Dark Brown and Black soil zones. A barley-field pea IWM system in the Black soil zone at Lacombe, Alberta, and a wheat-canola IWM system in the Dark Brown soil zone at Lethbridge, Alberta, and Scott, Saskatchewan, were used to assess contributions of seeding date (April or May), seeding rate (recommended or 150% of recommended), fertilizer timing (fall or spring), and in-crop herbicide rate (50% or 100% of recommended). The factorial set of treatments was applied in 4 consecutive years at each site. For barley-field pea production, the highest contribution margin (CM) (returns over variable production costs) was earned with 50% of the recommended herbicide rate, spring application of N fertilizer, seeding barley later at the high seeding rate, and seeding field pea early at the recommended seeding rate. This IWM system had a CM benefit of at least $51 ha(-1) compared with current common practices. The wheat-canola system results were site specific. At Lethbridge, it was more profitable to use 50% of recommended herbicide rates and to seed both crops early, with an early seeding date being very important for canola. The CM of this IWM system was $48 ha(-1) higher than current common practices. At Scott, the wheat-canola system was more profitable with spring fertilizer application, 50% of the recommended herbicide rate, and an early seeding date for canola. The best IWM system had a CM $15 to $75 ha-1 higher, depending on the year, than common practices. Our results confirmed the economic merits of using IWM practices for cereal-oilseed and cereal-pulse cropping systems in these regions of western Canada.
  • Authors:
    • Duchovskiene, L.
    • Starkute, R.
    • Zalatorius, V.
  • Source: Straipsnis leidinyje: Sodininkystė ir daržininkystė
  • Volume: 25
  • Issue: 4
  • Year: 2006
  • Summary: In 2003-05 in Lithuanian Institute of Horticulture, in trial field for ecologically grown vegetables, plant availability for green manure and its influence on ecologically grown onions yield were evaluated. Investigated plants included: barley; barley with undersown clover; summer wheat, peas and oats; and rape. Control treatment was black fallow. The biomass of plants for green manure leaves in the soil was evaluated under different amounts of organic matter. The highest amount of green matter (43.2 t/ha) was from peas and oats; summer wheat showed 32.5 t/ha; barely with undersown clover, 30.2 t/ha; and the lowest was from barely and rape (24.5 and 27.0 t/ha, respectively). There were no significant differences in the number of Thrips tabaci between treatments. Green manure from peas and oats increase onion yield by 3.1%; green manure from summer wheat by 5.7%; and green manure from barely with undersown clover by 7.3%. The lowest impact for onion yield has had green manure from barely and rape. The highest number of weeds (191 unit/m 2) was found in onions grown after barely with undersown clover, while the lowest number of 29 unit/m 2 was in onions grown after peas and oats.
  • Authors:
    • Roostalu, H.
    • Astover, A.
    • Vasiliev, N.
    • Matveev, E.
  • Source: Agronomy Research
  • Volume: 4
  • Issue: 1
  • Year: 2006
  • Summary: For analysing agronomic efficiency and economic criteria, the results of variety comparison tests of cereals, performed in Estonia during twenty years, national statistics and the data of the survey of the Farm Accountancy Data Network (FADN) for 2000-2003 were summarised. Farms whose grain production contributed more than 75% to total output were selected for analysis. At present only -40-50% of the real yield potential of cereals is realised. In case of oilseed rape the utilisation of the yield potential is 60-65%. Among the cereals, the largest share is accounted for by barley with 25-43% and wheat with 15-29%. During four years (2000-2003), total inputs increased 21%. Total inputs were the highest in large farms. As an average for 2000-2003 FADN grain producers were profitable in all size groups but consideration of total labour costs indicates that small grain farms were unprofitable. Average farm family income was 1,376 EEK ha(-1). There is a non-linear relationship between farm size and economic indicators. Farm family income increases up to similar to 400 ha. The increase is most significant in the size range 40-200 ha where the increase in farm size by one hectare increases profit by 7.6 EEK ha(-1). Further increase will decelerate profit and the most efficient use of labour occurs in this size range as well. Cost benefit is the highest for farm size ranging from similar to 150 to 400 ha. Profit decreases with the increase in one annual work unit by 508 EEK ha(-1) and production becomes unprofitable in case a grain farm employs more than 2.6 workers per 100 ha.
  • Authors:
    • Yamaguchi, J.
  • Source: JIRCAS International Symposium Series
  • Issue: 13
  • Year: 2006
  • Summary: Involvement in environment issues and population carrying capacity was analysed based on three typical agricultural systems: slash and burn semi-sedentary agriculture, recycling agriculture in which organic materials are re-used, and non-cyclic agriculture in which nutrient supply depends chiefly on chemical fertilizers. Our analysis showed that, due to its high productivity, non-cyclic agriculture is obligatory to support an ever-growing population and to offset the resultant continuous loss of arable land per person. Fertilizers to be applied should be quantified to exactly meet the balance between plant requirements and natural supply. Excess application of fertilizers should always be avoided. Degradation of soils in the tropics is caused mainly by water and wind erosion, and to a lesser extent from nutrient disturbance (mainly from shortages). The environmental protective effects of permanent crops are shown using two examples. One is in Erimo, Hokkaido (Japan), where fishermen have revived their local fisheries by reforesting the coastline, and the other in Tanzania where indigenous people thrive on the permanent culture of bananas. In the tropics, the use of vegetation as soil cover confers advantages in highly fragile areas, if only because of protection from erosion. The introduction of permanent crops is an alternative to establishing co-existence between agriculture and the environment.
  • Authors:
    • Robertson, G. P.
    • Grandy, A. S.
    • Thelen, K. D.
  • Source: Agronomy Journal
  • Volume: 98
  • Issue: 6
  • Year: 2006
  • Summary: No-till management has been shown to increase soil aggregation, reduce erosion rates, and increase soil organic matter across a range of soil types, cropping systems, and climates. Few agricultural practices provide similar opportunities to deliver positive benefits for farmers, society, and the environment. The potential benefits of no-till are not being fully realized, however, in large part because no-till is rarely practiced continuously and many fields suitable for no-till are still conventionally tilled. We present here three arguments, based on recent research, in support of the agronomic and environmental benefits of continuous no-till: (i) although there exist agronomic challenges with no-till, long-term yields in these systems can equal or exceed those in tilled soils; (ii) cultivating no-till systems can decrease soil aggregation and accelerate C and N losses so rapidly that years of soil restoration can be undone within weeks to months; and (iii) over time, changes in soil structure and organic matter, coupled with producer adaptation to the need for spatially and temporally explicit chemical applications, increase plant N availability and reduce environmental N losses. At least in theory, then, continuous no-till can be widely practiced to improve the environment and maintain yields with little or no economic sacrifice by producers. In practice, however, many diverse challenges still limit no-till adoption in different regions. These challenges are surmountable, but potential solutions need to be interdisciplinary and address the ecological and especially the social and economic constraints to deploying continuous no-till.
  • Authors:
    • Ding, H.
    • Edis, R.
    • Zhang, Y.
    • Chen, D.
    • Li, Y.
  • Source: Global Biogeochemical Cycles
  • Volume: 19
  • Year: 2005
  • Authors:
    • Desjardins, R. L.
    • Trzcinski, M. K.
    • Pattey, E.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 72
  • Issue: 2
  • Year: 2005
  • Summary: Greenhouse gas emissions from the agricultural sector can be reduced through implementation of improved management practices. For example, the choice of manure storage method should be based on environmental decision criteria, as well as production capacity. In this study, greenhouse gas emissions from three methods of storing dairy and beef cattle manure were compared during the summer period. The emissions of CH4,N2O and CO2 from manure stored as slurry, stockpile, and compost were measured using a flow-through closed chamber. The largest combined N2O-CH4 emissions in CO2 equivalent were observed from the slurry storage, followed by the stockpile and lastly the passively aerated compost. This ranking was governed by CH4 emissions in relation to the degree of aerobic conditions within the manure. The radiative forcing in CO2 equivalent from the stockpiled manure was 1.46 times higher than from the compost for both types of cattle manure. It was almost twice as high from the dairy cattle manure slurry and four to seven times higher from the beef cattle manure slurry than from the compost. The potential reduction of GHG was estimated, by extrapolating the results of the study to all of Canada. By composting all the cattle manure stored as slurry and stockpile, a reduction of 0.70 Tg CO2-eq year-1 would be achieved. Similarly, by collecting and burning CH4 emissions from existing slurry facilities, a reduction of 0.76 Tg CO2-eq year-1 would be achieved. New CH4 emission factors were estimated based on these results and incorporated into the IPCC methodology. For North America under cool conditions, the CH4 emission factors would be 45 kg CH4 hd-1 year-1for dairy cattle manure rather than 36 kg CH4 hd-1 year-1, and 3kgCH4 hd-1 year-1 for beef cattle manure rather than 1 kg CH4 hd-1 year-1.
  • Authors:
    • Paustian,Keith
    • Cole,C. Vernon
    • Sauerbeck,Dieter
    • Sampson,Neil
    • Peairs,F. B.
    • Bean,B.
    • Gossen,B. D.
  • Source: Agronomy Journal
  • Volume: 97
  • Issue: 2
  • Year: 2005
  • Summary: The intensification of traditional wheat (Triticum aestivum L.)-fallow production systems may have important consequences for management of insects, pathogens, and weeds in Great Plains dryland production systems. Assessment of these consequences is difficult due to the diversity of production systems, environmental conditions, and pests found in the region. Certain pest groups, such as weeds, traditionally controlled during the fallow period, may be favored by intensified cropping while others, such as those specializing on wheat, should be disadvantaged. Changes in pest and disease complexes will likely be evolutionary rather than revolutionary, as has been the case with other significant changes in production practices. Preventive practices in dryland production systems currently emphasize the control of grassy weeds while intensified systems may have less emphasis on the control of volunteer wheat. Crop rotation will remain a key avoidance strategy for pathogens and will help broaden herbicide options. Pest monitoring provides essential information on pest activity and environmental conditions and will become more complex as production systems are intensified. Important suppressive practices for dryland production systems include conservation biological control, tillage, and chemical controls. Chemical control, in particular, is expected to become more complicated due to drift concerns, rotational restrictions, the possible need for herbicide-tolerant crops, and the development of weed populations resistant to glyphosate. Pest management requirements should be considered during cropping system design and establishment.