• Authors:
    • Stenberg, B.
    • Stenberg, M.
    • Rydberg, T.
  • Source: Applied Soil Ecology
  • Volume: 14
  • Issue: 2
  • Year: 2000
  • Summary: The effects of reduced tillage and lime on crop yield and soil physical and microbial properties were studied in a weakly-structured silty clay loam soil at a site in Sweden. Two autumn primary tillage practices were compared, mouldboard ploughing to 20-25 cm and cultivation to 12 cm. Seedbed preparation was carried out by several harrowing operations in the mouldboard ploughed treatment, and with a harrow in the same operation as sowing in the shallow cultivation treatment. The tillage treatments were applied alone or were combined with liming aimed at soil structural improvement. Lime was added as 6.5 t CaO ha -1 before the start of the experiment and mixed into the top 12 cm of soil with a disc cultivator. A 4-year crop rotation was used: spring barley, spring oilseed rape, spring/winter wheat and oats, and all crops were compared each year. Crop residues were retained in the experiment and incorporated at cultivation. Aggregate stability was improved by the shallower tillage depth, probably as an effect of an increase in soil organic matter and a more active microbial biomass. Liming had little effect on soil structure variables but increased microbial activity to some extent. This was reflected in higher crop yields, especially when the shallow tillage depth was combined with liming. Penetration resistance in the seedbed subsoil was highest when mouldboard ploughing was carried out in plots without liming. Data were examined with principal component analyses, and the structures in the data were presented as scores and loading plots, which showed groupings between samples and relationships between variables, respectively.
  • Authors:
    • Clark, K.
  • Source: Regional on-farm experiments 1999: Deniliquin, Finley, Hillston, Leeton & Beckom agronomy districts
  • Year: 2000
  • Summary: Tabulated yield data are presented from variety trials conducted throughout New South Wales, Australia, for barley, rape, lentils, lupins, oats, peas, wheat and narbon ( Vicia narbonensis).
  • Authors:
    • Gurin, A. G.
  • Source: Sadovodstvo i Vinogradarstvo
  • Issue: 1
  • Year: 2000
  • Summary: In Russia, strips of shelter plants are sometimes grown between the rows of strawberries, so that at the end of the growing season the first frosts will kill off the tops of these plants which then fall and cover the strawberry plants like a mulch, and help to retain a protective snow cover through the winter. An account is given of the performance of oats, barley, rape, and mustard sown as shelter plants between the rows of Redgauntlet strawberries, with details of the snow accumulation and of the strawberry yields. The shelter plants did depress the growth of the strawberry plants somewhat, but had little or no effect on fruit yields, and also significantly reduced weed growth.
  • Authors:
    • Knezevic, S. Z.
    • Leeson, J. Y.
    • Thomas, A. G.
    • Acker, R. C. van
    • Frick, B. L.
  • Source: Canadian Journal of Plant Science
  • Volume: 80
  • Issue: 4
  • Year: 2000
  • Summary: In 1997, a weed survey was conducted during July and August in fields of wheat, barley, oat, canola [rape] and flax in Manitoba, Canada. Field selection was based on a stratified-random sampling methodology using ecodistricts as strata. Species in the Poaceae family were most commonly observed in the survey, followed by species in the Polygonaceae, Asteraceae and Brassicaceae families. The six most abundant weed species were green foxtail ( Setaria viridis), wild oats ( Avena fatua), wild buckwheat ( Polygonum convolvulus) [ Fallopia convolvulus], Canada thistle ( Cirsium arvense), red-root pigweed ( Amaranthus retroflexus) and wild mustard ( Sinapis arvensis). The survey highlighted significant differences between ecoregions and between crops in residual weed infestations. The weed community in the Boreal Transition ecoregion was dominated by seven species, whereas fields in the Aspen Parkland and Lake Manitoba Plain ecoregions were dominated by two species and the Interlake Plain ecoregion was dominated by only one species. Although significant differences were found between the weed communities in crops, they were not as great as differences between ecoregions. The Manitoba residual weed community in 1997 was very similar to that reported for 1978-81 and 1986, suggesting that the same species should remain a focus for weed management.
  • Authors:
    • Bertholdsson, N. O.
  • Source: Sveriges Utsädesförenings Tidskrift
  • Volume: 110
  • Issue: 4
  • Year: 2000
  • Summary: The use of hydroponic techniques to measure the response to stress by cereals is discussed with reference to studies on drought, low N inputs and crop weed competition with barley, wheat, oats, triticale and rape.
  • Authors:
    • Follett,R. F.
    • Reule,C. A.
    • Halvorson,A. D.
  • Source: Soil Science Society of America Journal
  • Volume: 63
  • Issue: 4
  • Year: 1999
  • Summary: No-till (NT) increases the potential to crop more frequently in the Great Plains than with the conventional-till (CT) crop-fallow farming system. More frequent cropping requires N input to maintain economical yields. We evaluated the effects of N Fertilization on crop residue production and its subsequent effects on soil organic C (SOC) and total soil N (TSN) in a dryland NT annual cropping system. Six N rates (0, 22, 45, 67, 90, and 134 kg N ha(-1)) were applied to the same plots from 1984 through 1994, except 1988 when rates sere reduced 50%, on a Weld silt loam (fine, smectitic, mesic Aridic Argiustoll). Spring hal leg (Hordeum vulgare L.), corn (Zea mays L.),winter wheat (Triticum aestivum L.), and oat (Avena sativa L.)-pea (Lathyrus tingitanus L.) hay were grown in rotation. Crop residue production varied with crop and gear. Estimated average annual aboveground residue returned to the soil (excluding hay years) was 2925, 3845, 4354, 4365, 4371, and 4615 kg ha(-1), while estimated annual contributions to belowground (root) residue C were 1060, 1397, 1729, 1992, 1952, and 2031 kg C ha(-1) for the above N rates, respectively. The increased amount of crop residue returned to the soil with increasing N rate resulted in increased SOC and TSN levels in the 0- to 7.5-cm soil depth after 11 crops. The fraction of applied N fertilizer in the crop residue decreased with increasing N rate. Soil bulk density (D-b) in the 0- to 7.5-cm soil depth decreased as SOC increased, The increase in SOC with N fertilization contributes to improved soil quality and productivity, and increased efficiency of C sequestration into the soil. Carbon sequestration can be enhanced by increasing crop residue production through adequate N fertility.
  • Authors:
    • Azooz, R. H.
    • Franzluebbers, A. J.
    • Arshad, M. A.
  • Source: Soil & Tillage Research
  • Volume: 53
  • Issue: 1
  • Year: 1999
  • Summary: Improvement in soil quality to maintain high production and reduce negative environmental impacts is necessary for alternative crop production strategies to become socially acceptable and viable in the long-term. No-tillage (NT) management of the predominantly small grain region of western Canada has the potential to curb soil erosion and increase profitability. An understanding of the direct effects of NT on soil properties is necessary to evaluate its potential for sustained long-term productivity. We have compiled data collected from two sites in northern British Columbia to ascertain the long-term effects of conventional tillage (CT) and NT on soil components thought to be important in surface soil structural improvement. Soil water retention was greater under NT compared with CT without dramatically altering bulk density due to redistribution of pore size classes into more small pores and less large pores. Soil organic C was greater under NT than under CT nearest the soil surface. Water-stable aggregation improved under NT compared with CT, perhaps because more soil organic C was sequestered within macroaggregates under NT compared with CT that helped to stabilize these aggregates. Steady-state water infiltration was greater under NT than under CT as a result of soil structural improvements associated with surface residue accumulation and lack of soil disturbance. Barley (Hordeum vulgave L.) yield tended to be greater under NT than under CT in years of low rainfall as a result of improvements in soil water retention and transmission that may have provided a better environment for root development. Our data indicate that NT is a viable management strategy to improve soil quality in the cold, semiarid region of western Canada. This strategy could lead to high production, minimal negative environmental impacts, and a socially-acceptable farming system.
  • Authors:
    • Parker, J. P.
    • Scott, A.
    • Ball, B. C.
  • Source: Soil & Tillage Research
  • Volume: 53
  • Issue: 1
  • Year: 1999
  • Summary: Tillage practices and weather affect the release of greenhouse gases but there have been few integrated studies of the quantities released or the mechanisms involved. No-tillage may increase emissions of nitrous oxide (N2O) and the fixation of carbon by decreasing carbon dioxide (CO2) emissions. Tillage may also decrease the oxidation rate of atmospheric methane (CH4) in aerobic soil. These effects are partly due to compaction and to the lack of both soil disturbance and residue incorporation. Our objective was to investigate how tillage practices, soil conditions and weather interact to influence greenhouse gas emissions. Here we present early measurements of N2O and CO2 emission and CH4 oxidation in two field experiments in Scotland under a cool moist climate, one involving soil compaction plus residue incorporation and the other involving no-tillage and two depths of mouldboard ploughing of a former grass sward. The experiments were located 10-15 km south of Edinburgh on a cambisol and a gleysol. In order to monitor emissions regularly, at short intervals and over long periods, a novel automatic gas sampling system which allows subsequent automated determination of both N2O and CO2 fluxes was used. Both N2O and CO2 fluxes were episodic and strongly dependent on rainfall. Peak N2O emissions were mainly associated with heavy rainfalls after fertilisation, particularly with no-tilled and compact soils. In the tillage experiment, N2O fluxes and treatment differences were greater under spring barley (Hordeum vulgare L.) (up to 600 g N ha-1 per day) than under winter barley. CO2 emissions in the few weeks after sowing were not strongly influenced by tillage and diurnal variations were related to soil temperature. However, periods of low or zero CO2 fluxes and very high N2O fluxes under no-tillage were associated with reduced gas diffusivity and air-filled porosity, both caused by heavy rainfall. Early results show that CH4 oxidation rates may best be preserved by no-tillage. The quality of the loam/clay-loams and the climate in these experiments makes ploughing, preferably to 300 mm depth, and the control of compaction necessary to minimise soil N2O and CO2 losses. The gas exchange response of different soil types to tillage, particularly methane oxidation rate which is affected by long-term soil structural damage, is a potentially useful aspect of soil quality when taken in conjunction with other qualities.
  • Authors:
    • Tanni, R.
    • Pietola, L.
  • Source: Agricultural and Food Science in Finland
  • Volume: 8
  • Issue: 4/5
  • Year: 1999
  • Summary: The role of plant growth regulators (PGR) in nitrogen (N) fertilization of spring wheat and oats (CCC [chlormequat]), fodder barley (etephon/mepiquat) an oilseed rape (etephone) in crop rotation was studied in 1993-96 on loamy clay soil. Carry over effect of the N fertilization rates (0-180 kg/ha) was evaluated in 1997. N fertilization rate for the best grain/seed yield (120-150 kg/ha) was not affected by PGRs. The seed and N yields of oilseed rape were improved frequently by the recommended use of PGR. The yield of oats increased in 1995-96. Even though PGR effectively shortened the plant height of spring wheat, the grain yield increased only in 1995. N yield of wheat grains was not increased. Response of fodder barley to PGR was insignificant or even negative in 1995. The data suggest that PGRs may decrease some N leaching at high N rates by improving N uptake by grain/seeds, if the yield is improved. The carryover study showed that in soils with no N fertilization, as well as in soils of high N rates, N uptake was higher than in soils with moderate N fertilization (60-90 kg/ha), independent of PGRs. According to soil mineral N contents, N leaching risk was significant (15-35 kg/ha) only after dry and warm late seasons. After a favourable season of high yields, the N rates did not significantly affect soil mineral N contents.
  • Authors:
    • Avci, M.
  • Source: Efficient soil water use: the key to sustainable crop production in the dry areas of West Asia, and North and Sub-Saharan Africa. Proceedings of the workshops organized by the Optimizing Soil Water Use Consortium, Niamey, Niger, 26-30 April, 1998, Amman, J
  • Year: 1999
  • Summary: Semi-arid areas cover about 55% of Turkey and are mainly found in the Central Anatolian Plateau. The main crop production systems are fallow/wheat and legume/wheat. Wheat is generally prone to droughts, which severely affect the yields. Research on soil moisture use in fallow-wheat systems started in the 1930s. Its focus was on water interception and conservation techniques, and detailed research on rainfall interception led to practices which have been adopted by most of the plateau farmers. In the 1980s research focused on the replacement of fallow by a crop in the rotation systems. In most areas, fallow can best be replaced in terms of yield by forage crops and economically by edible legumes. Characterization of the other regions will identify fallow or continuous cropping target areas, and extrapolation of research results to them. Regarding technologies, the importance of terracing for moisture conservation increases with the degree of slope and the occurrence of erosive rainfall. Contour tillage and sowing were effective only on steep slopes. Future research is needed on supplemental irrigation to increase the water-use efficiencies of the wheat and barley varieties especially developed for irrigation.