• Authors:
    • Carter, M. R.
  • Source: Agronomy Journal
  • Volume: 94
  • Issue: 1
  • Year: 2002
  • Summary: Soil quality concepts are commonly used to evaluate sustainable land management in agroecosystems. The objectives of this review were to trace the importance of soil organic matter (SOM) in Canadian sustainable land management studies and illustrate the role of SOM and aggregation in sustaining soil functions. Canadian studies on soil quality were initiated in the early 1980s and showed that loss of SOM and soil aggregate stability were standard features of nonsustainable land use. Subsequent studies have evaluated SOM quality using the following logical sequence: soil purpose and function, processes, properties and indicators, and methodology. Limiting steps in this soil quality framework are the questions of critical limits and standardization for soil properties. At present, critical limits for SOM are selected using a commonly accepted reference value or based on empirically derived relations between SOM and a specific soil process or function (e.g., soil fertility, productivity, or erodibility). Organic matter fractions (e.g., macro-organic matter, light fraction, microbial biomass, and mineralizable C) describe the quality of SOM. These fractions have biological significance for several soil functions and processes and are sensitive indicators of changes in total SOM. Total SOM influences soil compactibility, friability, and soil water-holding capacity while aggregated SOM has major implications for the functioning of soil in regulating air and water infiltration, conserving nutrients, and influencing soil permeability and erodibility. Overall, organic matter inputs, the dynamics of the sand-sized macro-organic matter, and the soil aggregation process are important factors in maintaining and regulating organic matter functioning in soil.
  • Authors:
    • Grove, J. H.
    • Diaz-Zorita, M.
  • Source: Soil & Tillage Research
  • Volume: 65
  • Issue: 1
  • Year: 2002
  • Summary: The western part of the Argentine Pampas is a subhumid and semiarid region consisting of extensive plain with deep sandy and sandy-loam soils. The agricultural system includes pastures in rotation with annual grain crops and grazed crops or continuous annual row cropping. The objective of this review was to present and discuss changes in soil properties due to different soil management systems, mainly no-tillage practices, in the western part of the Argentine Pampas. The effects of tillage, crop sequences under no-till, and grazing on soil properties and crop productivity have been studied since 1990 on loamy and sandy Haplic Phaeozem (Typic Hapludolls and Entic Hapludolls) and Haplic Kastanozem (Typic Haplustolls). A database developed from the yield and soil test records of growers affiliated with Regional Consortium for Agricultural Experimentation (CREA) were also utilized in the study. The results showed that soil organic C (SOC) content depends both on soil texture and soil management. SOC decreases when the length of the row crop cycle increases and also in moldboard plow and chisel-tillage systems. Pastures and no-till row crop sequences with more years of maize (Zea mays L.) and wheat (Triticum aestivum L.), than sunflower (Helianthus annus L.) or soybean (Glycine max (L.) Merrill) tended to increase the SOC content in the 0-20 cm layer. Deep tillage of no-till soils with compacted layers improved maize dry matter production but, in the same experiment, yield was increased more by nitrogen fertilization than by subsoil tillage. The grazing of crop residues increases the soil bulk density only in the 0-5 cm layer of tilled soils, but did not significantly change bulk density on soils under continuous no-till. Crop productivity was related to SOC content of the 0-20 cm layer of the soils. Due to the positive effect of SOC on crop yields, no-till soil management and pasture-annual row crop rotations are two practices that permit the development of sustainable production systems in the western part of the Argentine Pampas.
  • Authors:
    • Lajeunesse, J.
    • Pageau, D.
    • Legere, A.
    • Simard, M.
    • Warwick, S.
  • Source: Weed Technology
  • Volume: 16
  • Issue: 2
  • Year: 2002
  • Summary: The presence of volunteer rape ( B. napus [ B. napus var. oleifera]) is becoming a significant agroecological concern, given the large-scale use of herbicide-tolerant varieties in some areas. Our goal was to estimate the frequency and persistence of volunteer rape in Quebec cropping systems by surveying fields that included a single rape crop since 1995 in Quebec, Canada. A survey was conducted in 131 fields in the main rape-growing areas of Quebec: in the Saguenay-Lac Saint-Jean region and the Quebec City-La Pocatiere area, Canada, during June-August 2000. Volunteer rape plants were counted in 0.25-m 2 quadrats every 10 m along a W pattern, and every 15 m along the margins of 88 fields. Volunteer rape plants were found in 90% of the fields surveyed and in a wide range of crops, including cereal, maize, and soyabean. Average densities of 4.9 and 3.9 plants/m 2 were found a year after rape production in fields and field margins, respectively. Volunteer rape densities decreased significantly over time. However, volunteer plants were still present at low densities 4 and 5 years after production. Dense stands of volunteer rape were found before postemergence herbicide application in no-till fields (9.84.1 plants/m 2), suggesting that, contrary to what was suggested in the literature, seeds could become dormant in no-till as well as in tilled systems. A small proportion of the volunteer rape plants observed in no-till fields near Quebec City and Ottawa included plants that had overwintered, either originating from autumn-germinated seedlings, harvested adult plants that had grown new leaves before the onset of winter, or spring regrowth from the base of unharvested adult plants from experimental plots. The presence and persistence of low densities of volunteer rape may not have been a cause of concern until now. However, producers should be made more aware of the potential short-term and long-term problems associated with potential gene flow between different herbicide-tolerant rape (HT rape) varieties and also between HT rape and related weed species.
  • Authors:
    • Michalski, T.
    • Bartos, M.
  • Source: Progress in Plant Protection
  • Volume: 42
  • Issue: 2
  • Year: 2002
  • Summary: Experiments were conducted during 1996-99 in Poland to study the effect of sowing density on barley, oat, wheat and triticale weed infestation. The cereals were sown in 4 densities, starting from 400 grains of barley and 650 grains of the other species (100%) and consequently reduced to 80, 60 and 40%. Number and weight of weeds in each year was seriously diverse. Weed infestation was the smallest (mean 27 weeds/m 2) at high sowing density and increased with a decrease in sowing density, reaching 88 weeds at the smallest density of cereals. The reduction of sowing density by 20% increased weed density 40-50%. The most frequent weeds were Setaria viridis and cultivated rape ( Brassica napus var. oleifera).
  • Authors:
    • Moerkerk, M.
    • Niknam, S. R.
    • Cousens, R.
  • Source: 13th Australian Weeds Conference: weeds "threats now and forever?", Sheraton Perth Hotel, Perth, Western Australia, 8-13 September 2002: papers and proceedings 2002
  • Year: 2002
  • Summary: This paper reports on surveys of farmers' seed boxes, which were carried out in the Wimmera and Mallee regions of Victoria in 2001. From seeds ready to be sown, 160 cereal (mainly wheat and barley) and pulse samples (mainly lentils, beans and peas) were collected and the level and species of weed seed were determined. For lentils (28 samples), the seed box survey was followed up with a paddock survey at flowering and the determination of foreign seed material in the final harvested grain. A wide range of weed species was found in the farmer-retained seed. Farmer-retained seed also contained more weed seeds than certified seed. The main foreign seeds in cereals were annual ryegrass ( Lolium rigidum), volunteer canola, volunteer barley, wild oats ( Avena spp.), silver grass ( Vulpia bromoides), volunteer wheat, lesser canary grass ( Phalaris minor), brome grass ( Bromus spp.), volunteer oats and paradoxa grass ( Phalaris paradoxa). For lentils, a number of common weeds were identified which tend to persist in the cropping system and replenish the seed bank. Annual ryegrass was identified as the most problematic weed. Other weeds such as vetch ( Vicia sativa) and bedstraw ( Galium tricornutum) could become serious problems in pulses if effective management practices are not found soon.
  • Authors:
    • Nielsen, G.
    • Mortensen, D.
    • McGinn, S.
    • Coen, G.
    • Caprio, J.
    • Waltman, S.
    • Padbury, G.
    • Sinclair, R.
  • Source: Agronomy Journal
  • Volume: 94
  • Issue: 2
  • Year: 2002
  • Summary: The northern Great Plains have long been dominated by conventional tillage systems and cereal-based rotations including summer fallow. Over the last decade, however, the use of conservation tillage systems has markedly increased and, through improved moisture storage, has provided an opportunity for more diversified extended rotations including oilseed, pulse, and forage crops throughout the region. Considerable research is being carried out to assess the adaptability of these new crops and to develop appropriate management strategies. Typically, this type of agronomic research is carried out at plot-sized research sites, with the findings then being extrapolated to surrounding regions where growing conditions are thought to be reasonably similar. Because the environment itself largely dictates the success of a particular cropping system, extrapolation requires knowledge of the environmental conditions of the region and, in particular, the interaction of environmental components of soil and climate in relation to specific crop requirements. This paper describes 14 agroecoregions in the northern Great Plains and provides an initial framework for extrapolating agronomic information at broad regional scales. Because climate is the dominant crop production factor in the region, most of the agroecosystems represent broad climatic zones. Each agroecoregion is described in terms of its soil and landscape characteristics, with a particular focus being given to likely key environmental parameters related to the production of the new oilseed, pulse, and forage crops being introduced in the region.
  • Authors:
    • Carlyle, W. J.
  • Source: The Geographical Journal
  • Volume: 168
  • Issue: 2
  • Year: 2002
  • Summary: Changes in cropping patterns in the Canadian Prairies are examined from the early 1960s to the mid-1990s using census data. Patterns of change within the region are mapped by census division using averaged proportions of land in crops occupied by the main crops for three pairs of census years. Spring wheat and oat have undergone the most significant relative declines. Canola increased dramatically from being the sixth-ranked crop by area in the early 1960s to the third-ranked crop by area by the 1990s. The main change in the Brown soil zone has been a large decline in spring wheat and a compensatory gain in durum wheat. Increases in special crops, especially pulse crops, canola and durum wheat have offset a substantial decline in spring wheat in the Dark Brown soil zone. Barley, tame hay and especially canola have increased at the expense of spring wheat, oat and flaxseed in the Black and Gray soil zones. Prices, transportation costs, changing export markets, crop breeding and local processing all have contributed to these changes.
  • Authors:
    • Thill, D. C.
    • Daugovish, O.
    • Shafii, B.
  • Source: Weed Science
  • Volume: 50
  • Issue: 5
  • Year: 2002
  • Summary: Wild oat, a troublesome weed in small grain cereals, infests about 11 million ha of cropland in the United States Diversifying cereal production with alternative crops, such as yellow mustard and canola, provides flexible cropping systems, decreases production risks, and may allow more effective weed suppression A greenhouse study was conducted to assess the competitive ability of yellow mustard and canola with wild oat in 1999 and 2000, using replacement series interference experiments to relate the results to plant development stages Yellow mustard, regardless of its proportion in mixture, reduced aboveground biomass of wild oat 33 to 66%, leaf and tiller number 34 to 36%, and panicle production 58% compared with wild oat in monoculture Canola did not affect wild oat biomass in mixtures Yellow mustard per plant biomass in 2000 and inflorescence production in 1999 decreased 30 and 20% with increased density of yellow mustard in mixtures Yellow mustard biomass was not affected by the addition of wild oat to the mixture, indicating the greater importance of intraspecific competition between yellow mustard relative to interspecific competition with wild oat Canola per plant biomass was affected more by interspecific competition with wild oat than by intraspecific competition A second greenhouse experiment was conducted to compare plant height and biomass accumulation by the three species over 7 wk Yellow mustard had the greatest biomass accumulation and plant elongation rate, followed by canola and wild oat The greater competitive ability of yellow mustard with wild oat, compared with canola, is likely associated with the rapid growth and canopy elevation of yellow mustard.
  • Authors:
    • UK, National Institute of Agricultural Botany (NIAB)
  • Source: Pocket guide to varieties of cereals, oilseeds & pulses for autumn 2002
  • Year: 2002
  • Summary: This edition presents information on the autumn sown varieties of wheat, barley, oats, triticale, rye, durum wheat, oilseed rape, linseed, peas, lupins and beans. Individual information on each variety is given, including variety notes, yield performance, relative ranking position in different environments and a summary of the important character ratings from the Recommended Lists.
  • Authors:
    • McNew, R. W.
    • Bacon, R. K.
    • Moldenhauer, K. A. K.
    • Windham, T. E.
    • Anders, M. M.
    • Cartwright, R. D.
    • Gibbons, J. W.
  • Source: Research Series - Arkansas Agricultural Experiment Station 2000 No. 476
  • Issue: 495
  • Year: 2002
  • Summary: Net returns for the full-season 2000 crop treatment combinations were between $89.57/acre for the continuous rice, no-till, enhanced fertility, 'LaGrue' treatment combination and $326.71/acre for the rice following corn, conventional tillage, standard fertility, 'Wells' treatment combination. Net returns, on average, were lowest ($141.49/acre) for the continuous rice rotation and highest ($234.61/acre) for the rice following soybean rotation. Lower production costs from the no-till plots were more than offset by increased yields in the conventional till plots resulting in higher net returns for the conventional tillage plots. The enhanced fertility treatment did not result in sufficient yield gains to offset fertilizer costs, thus net returns were higher for the standard fertility treatments. Consistently higher grain yields from Wells resulted in overall higher net returns from this variety. The only short-season rice variety combination resulting in positive net returns was with the variety 'XL-6'. Overall grain yields declined from 178 bu/acre in 2000 to 158 bu/acre in 2001. The mean grain yield from the continuous rice rotation was approximately 20 bu/acre lower than rice following soybean or corn. The enhanced fertility plots yielded only 6 bu/acre more than the standard fertility treatment. Yields declined in the short-duration rice treatments with highest grain yields from the variety XL-6. Water-use measurements indicated that, on average, all rice plots used approximately 29 acre-inches of irrigation water during the season. Water savings came from a reduced need to flush no-till plots. Above-ground plant nutrient uptake values indicated that the variety Wells generally took up more nutrients when compared to LaGrue. Rotation had the biggest impact on nutrient uptake in 2000 and there was a trend of increased nutrient uptake from the enhanced fertility treatments when compared to the standard fertility treatments even though there was no increase in grain yield.