• Authors:
    • Schroeder, K. L.
    • Paulitz, T. C.
    • Schillinger, W. F.
  • Source: Plant Disease
  • Volume: 94
  • Issue: 1
  • Year: 2010
  • Summary: An irrigated cropping systems experiment was conducted for 6 years in east-central Washington State to examine agronomic and economic alternatives to continuous annual winter wheat ( Triticum aestivum) with burning and plowing, and to determine how root diseases of cereals are influenced by management practices. The continuous winter wheat treatment with burning and plowing was compared with a 3-year no-till rotation of winter wheat-spring barley ( Hordeum vulgare)-winter canola ( Brassica napus) and three straw management treatments: burning, straw removal, and leaving the straw stubble standing after harvest. Take-all disease and inoculum increased from years 1 to 4 in the continuous winter wheat treatment with burning and plowing, reducing plant growth compared to the no-till treatments with crop rotations. Inoculum of Rhizoctonia solani AG-8 was significantly lower in the tilled treatment compared to the no-till treatments. Inoculum concentration of Fusarium pseudograminearum was higher than that of F. culmorum, and in one of three years, the former was higher in treatments with standing stubble and mechanical straw removal compared to burned treatments. Residue management method had no effect on Rhizoctonia inoculum, but spring barley had more crown roots and tillers and greater height with stubble burning. This 6-year study showed that irrigated winter wheat can be produced in a no-till rotation without major disease losses and demonstrated how cropping practices influence the dynamics of soilborne cereal diseases and inoculum over time.
  • Authors:
    • Kennedy, A. C.
    • Schillinger, W. F.
    • Young, D. L.
    • Paulitz, T. C.
  • Source: Field Crops Research
  • Volume: 115
  • Issue: 1
  • Year: 2010
  • Summary: Field burning of residue is a traditional management tool for irrigated wheat ( Triticum aestivum L.) production in the Inland Pacific Northwest of the United States (PNW) that can result in reduced air quality. A 6-year no-till field experiment to evaluate two complete cycles of a 3-year irrigated crop rotation of winter wheat-spring barley ( Hordeum vulgare L.)-winter canola ( Brassica napus L.) was sown (i) directly into standing residue of the previous crop, (ii) after mechanical removal of residue and, (iii) after burning of residue. The traditional practice of continuous annual winter wheat sown after burning residue and inverting the topsoil with a moldboard plow was included as a check treatment. Over-winter precipitation storage efficiency (PSE) was markedly improved when residue was not burned or burned and plowed after grain harvest. Grain yield of winter wheat trended higher in all no-till residue management treatments compared to the check treatment. Average grain yields of spring barley and canola were not significantly different among the no-till residue management treatments. Winter canola failed in 5 of 6 years due to a combination of a newly identified Rhizoctonia damping-off disease caused by Rhizoctonia solani AG-2-1 and cold temperatures that necessitated replanting to spring canola. Six-year average net returns over total costs were statistically equal over all four systems. All systems lost from $358 to $396 ha -1. Soil organic carbon (SOC) increased linearly each year with no-till at the 0-5 cm depth and accumulated at a slower rate at the 5-10 cm depth. Take-all of wheat caused by Gaeumannomyces graminis var. tritici was most severe in continuous annual winter wheat. The incidence and severity of Rhizoctonia on roots of wheat and inoculum of R. solani AG-8, was highest in the no-till treatments, but there was no grain yield loss due to this disease in any treatment. Residue management method had no consistent effect on Rhizoctonia root rot on barley. The annual winter grass downy brome ( Bromus tectorum L.) was problematic for winter wheat in the standing and mechanically removed residue treatments, but was controlled in the no-till residue burned and the burn and plow check. Another winter annual grass weed, rattail fescue ( Vulpia myuros L.), infested all no-till treatments. This was the first comprehensive and multidisciplinary no-till irrigated crop rotation study conducted in the Pacific Northwest.
  • Authors:
    • O'Donovan, J.
    • Harker, K.
    • Clayton, G.
    • Dosdall, L.
    • Hummel, J.
  • Source: Biological Control
  • Volume: 55
  • Issue: 3
  • Year: 2010
  • Summary: Several natural enemies regulate populations of root maggots ( Delia spp.) (Diptera: Anthomyiidae) in canola ( Brassica napus L.) in western Canada, among them the rove beetles Aleochara bilineata Gyllenhal and Aleochara verna Say (Coleoptera: Staphylinidae) and the hymenopteran Trybliographa rapae Westwood (Hymenoptera: Figitidae). Intercrops of canola and wheat ( Triticum aestivum L.) can be part of an integrated pest management strategy to reduce damage by Delia spp. to canola. We investigated several intercropping regimes of canola and wheat to determine effects on parasitism of Delia radicum (L.) and activity densities of adult A. bilineata and A. verna. Studies were conducted over four site-years in central Alberta, Canada in 2005 and 2006. Mean parasitism rates of D. radicum puparia by A. bilineata ranged from 7.27% to 81.69%. Increasing proportions of wheat in intercrops significantly reduced parasitism by A. bilineata in one site-year. Parasitism of D. radicum by T. rapae was not affected by intercropping; mean parasitism rates were between 2.17% and 14.55%. In one site-year combined parasitism by all parasitoids significantly increased with increasing canola as a proportion of total crop plant populations. Pitfall trap collections of adult A. bilineata increased with increasing proportions of canola in some site-years. Collections of A. verna adults were low relative to A. bilineata and were largely unaffected by intercropping. Although canola-wheat intercrops do not appear to favour parasitism of D. radicum, reductions in canola root damage by Delia larvae in intercrops, reported previously, suggest that canola-wheat intercrops may nevertheless be favourable as a crop protection strategy.
  • Authors:
    • Koocheki, A.
    • Rostami, L.
    • Khorramdel, S.
    • Shabahang, J.
  • Source: Proceedings of 3rd Iranian Weed Science Congress, Volume 1: Weed biology and ecophysiology, Babolsar, Iran, 17-18 February 2010
  • Volume: 1
  • Year: 2010
  • Summary: In order to investigate the effects of row intercropping wheat ( Triticum aestivum L.) with canola ( Brassica napus L.) on weed populations an experiment was conducted at the Agricultural Research Station of Ferdowsi University of Mashhad during fall growing season in 2009. For this purpose a randomized complete block design with three replications and six treatments was used. The treatments included canola and wheat alone, one row of canola + one row of wheat (1:1), two rows of canola+two rows of wheat (2:2), three rows of canola+three rows of wheat (3:3) and four rows of canola+four rows of wheat (4:4). Weed samplings were done in two stages (early and late of growing season). Then, weeds were counted and measured their dry matter. The results revealed that the highest and lowest amounts of relative frequency were obtained for ryegrass ( Lolium rigidum) and wild spinach ( Chenopodium album) with 2.27-6.82% and 36.36-62.79%, respectively. The maximum and minimum values of weeds dry matter were observed in wheat alone and 4:4, respectively. These findings suggest that intercropping increased diversity and it decreased weed number, density and population.
  • Authors:
    • Riffkin, P.
    • MacEwan, R.
    • Clough, A.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Symposium 4.2.1 Soil, energy and food security
  • Year: 2010
  • Summary: Dryland cropping in the high rainfall zone (HRZ) of southern Australia has the potential to produce high yields of cereals, canola and pulses. However, actual yields often fall well short of the estimated potential. A survey of grain growers in the HRZ was conducted to gain a greater understanding of the factors which may prevent growers from achieving potential yields. The survey was developed in consultation with growers, soil scientists and agronomists and distributed nationally through an industry magazine. The survey captured grower perceptions of soil and crop management using multiple choice questions and free comment sections. This paper documents the section of the survey pertaining to soils. In this survey, growers throughout the HRZ provided common responses regarding their use of some forms of tillage, trafficking, chemical soil amelioration techniques and physical soil engineering techniques. Different responses were evident depending upon region and farm size for issues such as the use of conventional tillage, raised beds and lime. The perceived success of various types of soil management options is also discussed. This information is valuable for those who wish to identify which regions or grower audiences should be targeted for research and extension in soil management.
  • Authors:
    • Claupein, W.
    • Mohring, J.
    • Bühler, A.
    • Gruber, S.
  • Source: European Journal of Agronomy
  • Volume: 33
  • Issue: 2
  • Year: 2010
  • Summary: Conventional tillage systems with high soil disturbance are being steadily replaced by tillage systems with low or no soil disturbance. An approach using three methodological steps (greenhouse, deliberate seed burial and field) revealed the long-term vertical distribution and losses of a soil seed bank as effects of different tillage operations. Seeds (oilseed rape; Brassica napus L.) and seed substitutes (plastic pellets) acted as models for a seed bank. (a) A pot experiment in the greenhouse showed that emergence rates were highest in soil depths of 1-5 cm. Germination and emergence was clearly reduced in depths of 0 and 7 cm, and emergence was completely inhibited at 12 cm. About 40-50% of seeds fell dormant in 0 and 12 cm depth, while almost no seeds fell dormant in 1-7 cm depth. (b) The high-dormancy variety Smart persisted to a high extent (60% of the initial seed number), but only 8% of seeds of the low-dormancy variety Express persisted over 4.5 years, after deliberate seed burial. Seed persistence was similar in all soil depths of 0-10 cm, 10-20 cm, and 20-30 cm. (c) The field experiment lasted from 2004 to 2009 and had different tillage treatments of inversion and non-inversion tillage: stubble tillage immediately after harvest combined with primary tillage by mouldboard plough (SP), chisel plough (SC), or rototiller (SRTT); primary tillage without stubble tillage by mouldboard plough (P), chisel plough (C); or no tillage (NT). The seed bank from an artificial seed rain of 20,000 seeds m -2 was significantly higher in all treatments with immediate stubble tillage, and clearly declined over time. However, seed bank depletion was slow once a seed bank had been established. The distribution of oilseed rape seeds and plastic pellets (7000 pellets m -2 broadcast) tended to equalise over the soil layers of 0-10, 10-20 and 20-30 cm over the course of five years. Since seed bank depletion was not attributable to a specific soil depth, shallow and low disturbance tillage did not generally result in a high seed persistence. More important than the depth was the timing of tillage. Though no-till systems provided conditions for seeds to fall dormant at the soil surface to a small extent, the effect lasted only for a limited time. Seed substitutes can be well used in methodological approaches to picture movement of seeds in the soil in order to optimize tillage strategies in agricultural practice.
  • Authors:
    • Duroueix, F.
    • Sauzet, G.
    • Lieven, J.
  • Source: 21ème Conférence du COLUMA. Journées Internationales sur la Lutte contre les Mauvaises Herbes, Dijon, France, 8-9 décembre, 2010
  • Year: 2010
  • Summary: CETIOM evaluated cultural methods during the intercropping period in the Berry region. Shallow tillage before winter oilseed rape (WOSR) or before winter barley were not effective to stimulate weed germination. Before winter wheat drilling, it gave whole satisfaction. Other results indicated a back-effect of the cultivation before WOSR establishment on the autumnal infestation of Crane's-bills. Deep cultivation (10-15 cms), realized a few weeks preceding the WOSR drilling, amplified the autumnal weed emergence, probably by bringing old seeds from depth to the surface and by breaking their dormancy. In comparison, a very shallow cultivation sharply reduced the subsequent weed infestation in the WOSR. Finally, if the interest of no-till drilling to limit the weed emergence was confirmed, that of the delayed drilling was not attested.
  • Authors:
    • Butterbach-Bahl, K.
    • Kiese, R.
    • Murphy, D. V.
    • Barton, L.
  • Source: GCB Bioenergy
  • Volume: 2
  • Issue: 1
  • Year: 2010
  • Summary: Understanding nitrous oxide (N2O) and methane (CH4) fluxes from agricultural soils in semi-arid climates is necessary to fully assess greenhouse gas emissions from bioenergy cropping systems, and to improve our knowledge of global terrestrial gaseous exchange. Canola is grown globally as a feedstock for biodiesel production, however, resulting soil greenhouse gas fluxes are rarely reported for semi-arid climates. We measured soil N2O and CH4 fluxes from a rain-fed canola crop in a semi-arid region of south-western Australia for 1 year on a subdaily basis. The site included N fertilized (75 kg N ha−1 yr−1) and nonfertilized plots. Daily N2O fluxes were low (−1.5 to 4.7 g N2O-N ha−1 day−1) and culminated in an annual loss of 128 g N2O-N ha−1 (standard error, 12 g N2O-N ha−1) from N fertilized soil and 80 g N2O-N ha−1 (standard error, 11 g N2O-N ha−1) from nonfertilized soil. Daily CH4 fluxes were also low (−10.3 to 11.9 g CH4-C ha−1 day−1), and did not differ with treatments, with an average annual net emission of 6.7 g CH4–C ha-1 (standard error, 20 g CH4-C ha-1). Greatest daily N2O fluxes occurred when the soil was fallow, and following a series of summer rainfall events. Summer rainfall increased soil water contents and available N, and occurred when soil temperatures were >25 °C, and when there was no active plant growth to compete with soil microorganisms for mineralized N; conditions known to promote N2O production. The proportion of N fertilizer emitted as N2O, after correction for emissions from the no N fertilizer treatment, was 0.06%; 17 times lower than IPCC default value for the application of synthetic N fertilizers to land (1.0%). Soil greenhouse gas fluxes from bioenergy crop production in semi-arid regions are likely to have less influence on the net global warming potential of biofuel production than in temperate climates.
  • Authors:
    • Barton, L.
    • Murphy, D. V.
    • Kiese, R.
    • Butterbach-Bahl, K.
  • Source: GCB Bioenergy
  • Volume: 2
  • Issue: 1
  • Year: 2010
  • Summary: Understanding nitrous oxide (N2O) and methane (CH4) fluxes from agricultural soils in semi-arid climates is necessary to fully assess greenhouse gas emissions from bioenergy cropping systems, and to improve our knowledge of global terrestrial gaseous exchange. Canola is grown globally as a feedstock for biodiesel production, however, resulting soil greenhouse gas fluxes are rarely reported for semi-arid climates. We measured soil N2O and CH4 fluxes from a rain-fed canola crop in a semi-arid region of south-western Australia for 1 year on a subdaily basis. The site included N fertilized (75 kg N ha−1 yr−1) and nonfertilized plots. Daily N2O fluxes were low (−1.5 to 4.7 g N2O-N ha−1 day−1) and culminated in an annual loss of 128 g N2O-N ha−1 (standard error, 12 g N2O-N ha−1) from N fertilized soil and 80 g N2O-N ha−1 (standard error, 11 g N2O-N ha−1) from nonfertilized soil. Daily CH4 fluxes were also low (−10.3 to 11.9 g CH4-C ha−1 day−1), and did not differ with treatments, with an average annual net emission of 6.7 g CH4–C ha−1 (standard error, 20 g CH4–C ha−1). Greatest daily N2O fluxes occurred when the soil was fallow, and following a series of summer rainfall events. Summer rainfall increased soil water contents and available N, and occurred when soil temperatures were >25 °C, and when there was no active plant growth to compete with soil microorganisms for mineralized N; conditions known to promote N2O production. The proportion of N fertilizer emitted as N2O, after correction for emissions from the no N fertilizer treatment, was 0.06%; 17 times lower than IPCC default value for the application of synthetic N fertilizers to land (1.0%). Soil greenhouse gas fluxes from bioenergy crop production in semi-arid regions are likely to have less influence on the net global warming potential of biofuel production than in temperate climates.
  • Authors:
    • Dejoux, J. F.
    • Aubinet, M.
    • Bernhofer, C.
    • Bodson, B.
    • Buchmann, N.
    • Carrara, A.
    • Cellier, P.
    • Di Tommasi, P.
    • Elbers, J. A.
    • Eugster, W.
    • Gruenwald, T.
    • Jacobs, C. M. J.
    • Jans, W. W. P.
    • Jones, M.
    • Kutsch, W.
    • Lanigan, G.
    • Magliulo, E.
    • Marloie, O.
    • Moors, E. J.
    • Moureaux, C.
    • Olioso, A.
    • Osborne, B.
    • Sanz, M. J.
    • Saunders, M.
    • Smith, P.
    • Soegaard, H.
    • Wattenbach, M.
    • Ceschia, E.
    • Beziat, P.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 139
  • Issue: 3
  • Year: 2010
  • Summary: The greenhouse gas budgets of 15 European crop sites covering a large climatic gradient and corresponding to 41 site-years were estimated. The sites included a wide range of management practices (organic and/or mineral fertilisation, tillage or ploughing, with or without straw removal, with or without irrigation, etc.) and were cultivated with 15 representative crop species common to Europe. At all sites, carbon inputs (organic fertilisation and seeds), carbon exports (harvest or fire) and net ecosystem production (NEP), measured with the eddy covariance technique, were calculated. The variability of the different terms and their relative contributions to the net ecosystem carbon budget (NECB) were analysed for all site-years, and the effect of management on NECB was assessed. To account for greenhouse gas (GHG) fluxes that were not directly measured on site, we estimated the emissions caused by field operations (EFO) for each site using emission factors from the literature. The EFO were added to the NECB to calculate the total GHG budget (GHGB) for a range of cropping systems and management regimes. N2O emissions were calculated following the IPCC (2007) guidelines, and CH4 emissions were estimated from the literature for the rice crop site only. At the other sites, CH4 emissions/oxidation were assumed to be negligible compared to other contributions to the net GHGB. Finally, we evaluated crop efficiencies (CE) in relation to global warming potential as the ratio of C exported from the field (yield) to the total GHGB. On average, NEP was negative (-284 +/- 228 gC m(-2) year(-1)), and most cropping systems behaved as atmospheric sinks, with sink strength generally increasing with the number of days of active vegetation. The NECB was, on average, 138 +/- 239 gC m(-2) year(-1), corresponding to an annual loss of about 2.6 +/- 4.5% of the soil organic C content, but with high uncertainty. Management strongly influenced the NECB, with organic fertilisation tending to lower the ecosystem carbon budget. On average, emissions caused by fertilisers (manufacturing, packaging, transport, storage and associated N2O emissions) represented close to 76% of EFO. The operation of machinery (use and maintenance) and the use of pesticides represented 9.7 and 1.6% of EFO, respectively. On average, the NEP (through uptake of CO2) represented 88% of the negative radiative forcing, and exported C represented 88% of the positive radiative forcing of a mean total GHGB of 203 +/- 253 gC-eq m(-2) year(-1). Finally, CE differed considerably among crops and according to management practices within a single crop. Because the CE was highly variable, it is not suitable at this stage for use as an emission factor for management recommendations, and more studies are needed to assess the effects of management on crop efficiency.