• Authors:
    • Spann, C.
    • Houlbrooke, D.
    • Hamilton, G.
    • Bakker, D.
  • Source: Australian Journal of Soil Research
  • Volume: 43
  • Issue: 5
  • Year: 2005
  • Summary: Waterlogging and poor soil structure in the root-zone of duplex soils in Western Australia has long been recognized as a major constraint to the production of agricultural crops (oats, barley, rape, field peas, wheat, lupins) and pastures. The effect of raised beds on waterlogging, soil structure, and productivity of duplex soils was investigated. Five experimental sites were established, monitored, and operated over 5 years as well as 3 larger scale demonstration sites which were operated over 4 or 3 years. Treatments consisted of raised beds and a normal no-till seedbed as the control. The beds were made with a bed former after the soil had been deep cultivated. Bulk density and steady-state infiltration rate observations indicated significant and lasting improvements in soil structure in the beds. The incidence of waterlogging in raised beds was reduced and this was accompanied by an increase in runoff from the raised beds. The average grain yield increase from the beds was 18% for a variety of crops across a range of climatic conditions and duplex soils. Seven years after the introduction of raised beds for broad-acre farming in Western Australia, more than an estimated 30 000 ha of crops is now grown on raised beds.
  • Authors:
    • Barker-Reid, F.
    • Gates, W. P.
    • Eckard, R. J.
    • Wilson, K.
    • Baigent, R.
    • Galbally, I. E.
    • Meyer, C. P.
    • Weeks, I. A.
  • Source: 4th International Symposium on non-CO2 Greenhouse Gases
  • Year: 2005
  • Authors:
    • Kelly, K.
    • Baigent, R.
    • Eckard, R.
    • Weeks, I.
    • Leuning, R.
    • Phillips, F.
    • Barker-Reid, F.
    • Gates, W.
    • Grace, P.
    • Galbally, I.
    • Meyer, M.
    • Bentley, S.
  • Source: Environmental Sciences
  • Volume: 2
  • Issue: 2-3
  • Year: 2005
  • Authors:
    • Schilizzi, S.
    • Flugge, F.
  • Source: Ecological Economics
  • Volume: 55
  • Issue: 4
  • Year: 2005
  • Authors:
    • O'Neil, K.
    • Nyiraneza ,J.
    • Leep, R.
    • Black, J. R.
    • Mutch, D.
    • Labarta, R.
    • Swinton, S. M.
    • Snapp, S. S.
  • Source: Agronomy Journal
  • Volume: 97
  • Issue: 1
  • Year: 2005
  • Summary: The integration of cover crops into cropping systems brings costs and benefits, both internal and external to the farm. Benefits include promoting pest-suppression, soil and water quality, nutrient cycling efficiency, and cash crop productivity. Costs of adopting cover crops include increased direct costs, potentially reduced income if cover crops interfere with other attractive crops, slow soil warming, difficulties in predicting N mineralization, and production expenses. Cover crop benefits tend to be higher in irrigated systems. The literature is reviewed here along with Michigan farmer experience to evaluate promising cover crop species for four niches.
  • Authors:
    • Johnson, D. W.
    • Moeltner, K.
    • van Kooten, G. C.
    • Manley, J.
  • Source: Climatic Change
  • Volume: 68
  • Issue: 1-2
  • Year: 2005
  • Summary: Carbon terrestrial sinks are often seen as a low-cost alternative to fuel switching and reduced fossil fuel use for lowering atmospheric CO2. To determine whether this is true for agriculture, one meta-regression analysis (52 studies, 536 observations) examines the costs of switching from conventional tillage to no-till, while another (51 studies, 374 observations) compares carbon accumulation under the two practices. Costs per ton of carbon uptake are determined by combining the two results. The viability of agricultural carbon sinks is found to vary by region and crop, with no-till representing a low-cost option in some regions (costs of less than $10 per tC), but a high-cost option in others (costs of $100-$400 per tC). A particularly important finding is that no-till cultivation may store no carbon at all if measurements are taken at sufficient depth. In some circumstances no-till cultivation may yield a triple dividend of carbon storage, increased returns and reduced soil erosion, but in many others creating carbon offset credits in agricultural soils is not cost effective because reduced tillage practices store little or no carbon.
  • Authors:
    • Johnsen, T. N.
    • McLain, J. E. T.
    • Emmerich, W.
    • Martens, D. A.
  • Source: Soil & Tillage Research
  • Volume: 83
  • Issue: 1
  • Year: 2005
  • Summary: Agriculture in the southwestern USA is limited by water supply due to high evaporation and limited seasonal precipitation. Where water is available, irrigation allows for production of a variety of agricultural and horticultural crops. This review assesses the impacts of agriculture on greenhouse gas emission and sequestration of atmospheric C in soils of the hot, dry region of the southwestern USA. In Texas, conservation tillage increased soil organic C by 0.28 Mg C ha(-1) year(-1) compared with more intensive tillage. Conversion of tilled row crops to the conservation reserve program or permanent pastures increased soil organic C by 0.32 +/- 0.50 Mg C ha(-1) year(-1). Soil organic C sequestration was dependent on rotation, previous cropping, and type of conservation tillage employed. Relatively few studies have interfaced management and C cycling to investigate the impacts of grazing management on soil organic C, and therefore, no estimate of C balance was available. Irrigated crop and pasture land in Idaho had soil organic C content 10-40 Mg C ha(-1) greater than in dryland, native grassland. Soil salinity must be controlled in cropland as soil organic C content was lower with increasing salinity. Despite 75% of the region's soils being classified as calcic, the potential for sequestration of C as soil carbonate has been only scantly investigated. The region may be a significant sink for atmospheric methane, although in general, trace gas flux from semiarid soils lacks adequate characterization. Agricultural impacts on C cycling will have to be better understood in order for effective C sequestration strategies to emerge. Published by Elsevier B.V.
  • Authors:
    • Milbrandt, A.
  • Source: Technical Report
  • Year: 2005
  • Authors:
    • Drenovsky, R. E.
    • Whisson, D. A.
    • Scow, K. M
    • Ingels, C. A.
  • Source: American Journal of Enology and Viticulture
  • Volume: 56
  • Issue: 1
  • Year: 2005
  • Summary: Several cover crop mixes were planted in a winegrape vineyard in Sacramento County to test their effects on vine growth, production, juice composition, soil microbial ecology, and gopher activity over a three-year period (1998 to 2000). The trial was conducted in a Vitis vinifera L. cv. Merlot vineyard on a silt loam soil. Vines were planted in 1993 on 5BB rootstock, spaced 2.1 x 3.4 m. The mixes used were: California native perennial grass (no-till), annual clover (no-till), green manure (disked), cereals (disked), and disked control. Cover crops were planted on either side of entire rows, with a disked alley separating treatment replicates. A 1.2-m herbicide strip was maintained under the vines. Drip irrigation and fertigation were applied uniformly across all treatments, but additional nitrogen fertilizer was applied to the grass mixes. Weed biomass increased in the clover mix but decreased in the native grass mix. Grapevine petiole nitrogen content was highest in the bell bean mix and very low in the native grass mix. There were very few differences in leaf water potential or pruning weights of the vines, and in yields or juice Brix, pH, or titratable acidity in any year. Cover-cropped soils had greater microbial biomass than disked or berm soils, and the no-till mixes had greater microbial biomass than the disked mixes. Gophers were very numerous in 1999 only, with nearly all activity exclusively in the clover mix.
  • 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.