• Authors:
    • Roskamp, G. K.
    • Glassman, K. R.
    • Ortiz-Ribbing, L. M.
    • Hallett, S. G.
  • Source: Plant Disease
  • Volume: 95
  • Issue: 4
  • Year: 2011
  • Summary: Common waterhemp ( Amaranthus rudis) and pigweeds ( Amaranthus spp.) are troublesome weeds in many cropping systems and have evolved resistance to several herbicides. Field trials to further develop Microsphaeropsis amaranthi and Phomopsis amaranthicola as bioherbicides for control of waterhemp and pigweeds were conducted to test the effectiveness of these organisms in irrigated and nonirrigated pumpkin and soybean plots over 2 years at three locations in western Illinois. The bioherbicide was applied with lecithin and vegetable oil at 187 liters ha -1 in 2008 and 374 liters ha -1 in 2009. Treatments included spore suspensions of M. amaranthi and P. amaranthicola alone, a mixture of both organisms, and sequential treatments of the organisms with halosulfuron-methyl (Sandea Herbicide) in pumpkin or glyphosate (Roundup Original Max Herbicide) in soybean. Bioherbicide effectiveness was estimated at approximately 7 and 14 days after treatment, as disease incidence, disease severity, percent weed control, and weed biomass reduction. Significant reductions in weed biomass occurred in treatments with one or both of the fungal organisms, and potential exists to tank mix M. amaranthi with halosulfuron-methyl. Leaf surface moisture and air temperatures following application may account for inconsistencies in field results between year and locations. These fungal organisms show potential as bioherbicides for weeds in the genus Amaranthus.
  • Authors:
    • Rosolem, C. A.
    • dos Santos, G. P.
    • Castoldi, G.
    • Pivetta, L. A.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 46
  • Issue: 11
  • Year: 2011
  • Summary: The objective of this work was to assess winter and spring crop effects on soybean root system growth, and on yield, and to compare a direct method (soil core sampling) with an indirect method (with rubidium) in evaluating the root system. The experimental design was a randomized complete block design, in a split-plot arrangement, with four replicates. Plots consisted of the winter crops, triticale (X Triticosecale) and sunflower (Helianthus annuus), and subplots of the spring crops, pearl millet (Pennisetum glaucum), forage sorghum (Sorghum bicolor) and sunn hemp (Crotalaria juncea), besides chisel tillage in 2003 and 2009. Soybean (Glycine max) was grown in the summer, and its root system was evaluated by physical sampling of the roots and by root activity assessment using rubidium. Changes in the architecture or in the activity of soybean roots did not affect yield. The distribution and activity of soybean roots were not significantly affected by the winter cover crops, but root growth was favored after millet and sorghum were grown in the spring. The direct measurement of the soybean root system with an auger has low correlation with root activity.
  • Authors:
    • Thorp, K. R.
    • Malone, R. W.
    • Helmers, M. J.
    • Qi, Z.
  • Source: Transactions of the ASABE
  • Volume: 54
  • Issue: 5
  • Year: 2011
  • Summary: Planting winter cover crops into corn-soybean rotations is a potential approach for reducing subsurface drainage and nitrate-nitrogen (NO(3)-N.) loss. However, the long-term impact of this practice needs investigation. We evaluated the RZWQM2 model against comprehensive field data (2005-2009) in Iowa and used this model to study the long-term (1970-2009) hydrologic and nitrogen cycling effects of a winter cover crop within a corn-soybean rotation. The calibrated RZWQM2 model satisfactorily simulated crop yield, biomass, and N uptake with percent error (PE) within +/- 15% and relative root mean square error (RRMSE) 0.50, ratio of RMSE to standard error (RSR)
  • Authors:
    • Pederson, C. H.
    • Christianson, R. D.
    • Helmers, M. J.
    • Qi, Z.
  • Source: Journal of Environmental Quality
  • Volume: 40
  • Issue: 5
  • Year: 2011
  • Summary: Nitrate-nitrogen (NO(3)-N) loading to surface water bodies from subsurface drainage is an environmental concern in the midwestern United States. The objective of this study was to investigate the effect of various land covers on NO(3)-N loss through subsurface drainage. Land-cover treatments included (i) conventional corn (Zea mays L.) (C) and soybean [Glycine max (L.) Merr.] (S); (ii) winter rye (Secale cereale L.) cover crop before corn (rC) and before soybean (rS); (iii) kura clover (Trifolium ambiguum M. Bieb.) as a living mulch for corn (kC); and (iv) perennial forage of orchardgrass (Dactylis glomerata L.) mixed with clovers (PF). In spring, total N uptake by aboveground biomass of rye in rC, rye in rS, kura clover in kC, and grasses in PF were 14.2, 31.8, 87.0, and 46.3 kg N ha(-1), respectively. Effect of land covers on subsurface drainage was not significant. The NO(3)-N loss was significantly lower for kC and PF than C and S treatments (p
  • Authors:
    • Kaleita, A. L.
    • Helmers, M. J.
    • Qi, Z.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 4
  • Year: 2011
  • Summary: Modification of land cover systems is being studied in subsurface drained Iowa croplands due to their potential benefits in increasing soil water and nitrogen depletion thus reducing drainage and NO(3)-N loss in the spring period. The objective of this study was to evaluate the impacts of modified land covers on soil water dynamics. In each individual year, modified land covers including winter rye-corn (rC), winter rye-soybean (rS), kura clover as a living mulch for corn (kC), and perennial forage (PF), as well as conventional corn (C) and soybean (S), were grown in subsurface drained plots in north-central Iowa. Results showed that subsurface drainage was not reduced under modified land covers in comparison to conventional corn and soybean. Soil water storage (SWS) was significantly reduced by PF treatments during the whole growing seasons and by kC during May through July when compared to the cropping system with corn or soybean only (p
  • Authors:
    • Passos, A. M. A. dos
    • Albuquerque, A. de
    • Resende, P. M. de
    • Baliza, D. P.
    • Reis, W. P.
    • Botrel, E. P.
  • Source: Revista de Agricultura
  • Volume: 86
  • Issue: 1
  • Year: 2011
  • Summary: The objective of this work was to compare the potential of the irrigated wheat under no tillage and conventional cropping systems, as well as to evaluate the performance of fifteen wheat cultivars in the two cropping systems, in succession to soybean crop, in the South of Minas Gerais. The experiment was carried out in the Federal University of Lavras (UFLA), in Lavras, MG, in the years of 2006/07 and 2007/08, in a split-block-designed scheme in a randomized complete block design, with three replications. The cropping systems (conventional and no-tillage) were installed in the rows and, in the columns, the fifteen wheat cultivars were distributed. The wheat yield and others agronomic characteristics were evaluated. The no-tillage provided an average increase of 25% in the organic matter levels in the topsoil layer in relation to previous levels and to conventional cropping system. The cultivars tested, independent of the agricultural year, significantly altered the grain yields and the agronomic characteristics. The high yield presented by the cultivars evaluated in this study indicates the high potential of the irrigated wheat cropped in succession to soybean crops, under similar climatic and soil conditions used in this study.
  • Authors:
    • Prabhakaran, N. K.
    • Chinnusamy, C.
    • Sangeetha, C.
  • Source: Madras Agricultural Journal
  • Volume: 98
  • Issue: 4/6
  • Year: 2011
  • Summary: A study was carried out to evaluate the effect of early post emergence herbicide, imazethapyr against weeds in irrigated soybean (Glycine max (L.) Merill) at Agricultural Research Station, Bhavanisagar. Weeds, viz., Dactyloctenium aegypticum, Acrach ne racemosa, Cyperus rotundus, Boerhaavia diffusa, Digera arvensis, Parthenium hysterophorous were the dominant weeds in the experimental field. Imazethapyr at 100 and 200 g ha -1 applied on 15 DAS provided 87 to 91% weed control efficiency compared to unweeded control. However, imazethapyr at 200 g ha -1 had slight phytotoxicity on soybean in the initial stages. Higher grain yield of 1645 kg ha -1 was obtained with application of imazethapyr 100 g ha -1.
  • Authors:
    • Prasad, T. V. R.
    • Kumar, V. K. K.
    • Sanjay, M. T.
    • Gowda, P. T.
  • Source: Journal of Crop and Weed
  • Volume: 7
  • Issue: 1
  • Year: 2011
  • Summary: A field experiment was conducted during Kharif 2007 and summer 2008 on sandy loam soil of Hebbal, Bangalore, University of Agricultural Sciences, Bangalore, to know the comparative performance of tank mix application of chlorimuron ethyl (Kloben 25% WP)+quizalofop-p-terfuryl (Pantera 4% EC) on controlling weeds in soybean and seed yield Tank mix combination of chlorimuron ethyl 9 g+quizalofop-p-tefuryl 40 g ai/ha -20 DAS with surfactant (1598 kg/ha) or without surfactant (1518 kg/ha) gave seed yield similar to hand weeding twice (1720 kg/ha), as result of good control of grasses, broad leaf weeds and sedge. Unweeded control lowered the yield by 61% mainly due to severe competition offered by grasses. Thus, use of chlorimuron ethyl 9 g+quizalofop-p-terfuryl 40 g ai/ha+0.2% surfactant (as tank mix) at 20 DAS can be used safely for broad spectrum weed control in irrigated soybean.
  • Authors:
    • Cella, A. J. S.
    • Ferraz, E. de C.
    • Barros, H. B.
    • Santos, E. R. dos
    • Capone, A.
    • Santos, A. F. dos
    • Fidelis, R. R.
  • Source: Revista Ceres
  • Volume: 58
  • Issue: 6
  • Year: 2011
  • Summary: The genetic diversity is one of the most important parameters evaluated by plant breeders in the early stages of a genetic improvement program. The objective of this paper was to evaluate the genetic divergence by means of multivariate techniques, among 48 soybean genotypes grown in irrigated lowland in the State of Tocantins, in order to select parents of hybrids for the production of oil and meal, as well as varieties of the panel, intended for human consumption. The experiment was conducted in the county Formoso do Araguaia - Tocantins, Brazil, in the cultivation of irrigated lowland, in the inter-cropping 2010. The experimental design was a randomized block with four replications. There was observed variability among the genotype tested. The Tocher's method, UPGMA and Canonic Variables agreed among themselves, and found four distinct groups. The following hybrids are promising for the production of soybean oil and meal for the M-Soy 8766, M-Soy 9144, A-7002 and M-soy 9056 with Amaralina RR crosses between and M-Soy 8766, M-Soy 9144 and Amaralina RR with BRSMG 790A, BRS 257, BRS 216 and BRS 213, are listed in order especially soybeans for human consumption.
  • Authors:
    • Munkhtsetseg, E.
    • Kimura, R.
    • Şaylan, L.
    • Kamichika, M.
  • Source: Theoretical and Applied Climatology
  • Volume: 105
  • Issue: 1/2
  • Year: 2011
  • Summary: In this study, variations in carbon dioxide (CO 2) fluxes resulting from gross primary production (GPP), net ecosystem exchange (NEE), and respiration ( Re) of soybean ( Glycine max L.) were investigated by the Eddy Covariance method during the growing period from June to November 2005 on an irrigated sand field at the Arid Land Research Center, Tottori University in Tottori, Japan. Although climatic conditions were humid and temperate, the soybeans required frequent irrigation because of the low water holding capacity of the sandy soil at the field site. Finally, it has been found that the accumulated NEE, GPP, and Re fluxes of soybean over 126 days amount to -93, 319, and 226 gC m -2, respectively. Furthermore, the average ratio of GPP to Re was 1.4 and the average ratio of NEE to GPP was about -0.29 for the growth period of soybean. Daily maximum NEE of -3.8 gC m -2 occurred when LAI was 1.1.