• Authors:
    • Szendrei, Z.
  • Source: Entomologia Experimentalis et Applicata
  • Volume: 143
  • Issue: 2
  • Year: 2012
  • Summary: Habitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds on M. quadrilineatus abundance was investigated experimentally in carrot [ Daucus carota L. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed-free plots. The preference of M. quadrilineatus for different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance of M. quadrilineatus in the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no-border treatment. However, spelt-bordered plots had 42% fewer M. quadrilineatus than three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affected M. quadrilineatus abundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf-weeds had about 59% fewer M. quadrilineatus compared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf-weeds repelled M. quadrilineatus relative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.
  • Authors:
    • Toth, T.
    • Arvay, J.
    • Tomas, J.
  • Source: Journal of Microbiology, Biotechnology and Food Sciences
  • Volume: 1
  • Issue: Special Issue
  • Year: 2012
  • Summary: The contents of heavy metals in plants were not in relation to contents of heavy metals in soil. Increased content of heavy metals in soils was not in consistency with content in plants. Usually content of heavy metals in plants according to our results were lower than their content in soil. Only the over limit contents of copper and cadmium were assessed in grain of barley and oat. The results of heavy metals content showed that dominant part on content of elements in plants have their mobile forms what depends on pH, content of organic matter in soil and portion of clay parts.
  • Authors:
    • Takebe, M.
    • Karasawa, T.
  • Source: Plant and Soil
  • Volume: 353
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims A field experiment was conducted where maintenance of indigenous arbuscular mycorrhizal (AM) fungal populations was attempted using AM host cover crops arranged temporally or spatially during growth of nonmycorrhizal crops. Methods To arrange AM hosts temporally, sunflower or oat was grown as a cover crop after non-host cropping (cabbage) or fallowing. In order to arrange AM hosts spatially, red clover, white clover or vetch was intercropped during growth of non-host cabbage. Results The AM colonization and growth of maize with previously introduced sunflower or oat were much greater than those without introduction of cover crops or those with introduction of non-host cover crops. The AM colonization and yield of winter wheat grown after cabbage with AM host intercropping were greater than those after cabbage only cropping, suggesting that arrangement of AM hosts between cabbage rows is effective for maintaining the AM fungal population in soil during non-host cropping. Conclusions Mycorrhizal hosts cropped after or during non-host cropping is an effective means to increase indigenous AM fungal populations. The results show that AM colonization, P uptake and productivity of crops after cultivation of nonmycorrhizal crops can be improved by arranging AM hosts temporally or spatially as cover crops.
  • Authors:
    • Singer, J. W.
    • Moorman, T. B.
    • Parkin, T. B.
    • Jaynes, D. B.
    • Kaspar, T. C.
  • Source: Agricultural Water Management
  • Volume: 110
  • Year: 2012
  • Summary: Much of the NO3 in the riverine waters of the upper Mississippi River basin in the United States originates from agricultural land used for corn (Zea mays L) and soybean (Glycine max [L] Merr.) production. Cover crops grown between maturity and planting of these crops are one approach for reducing losses of NO3. In this experiment, we evaluated the effectiveness of oat (Avena sativa L.) and rye (Secale cereale L.) cover crops in reducing NO3 concentrations and loads in subsurface drainage water. The oat fall cover crop was broadcast seeded into living corn and soybean crops before harvest in late August or early September and was killed by cold temperatures in late November or early December The rye winter cover crop, which had already been used annually for four years, was planted with a grain drill after corn and soybean harvest, overwintered, grew again in the spring, and was killed with herbicides before main crop planting. These treatments were evaluated in subsurface-drained field plots with an automated system for measuring drainage flow and collecting proportional samples for analysis of NO3 concentrations from each plot. The rye winter cover crop significantly reduced drainage water NO3 concentrations by 48% over five years, but this was less than the 58% reduction observed in its first four years of use. The oat fall cover crop reduced NO3 concentrations by 26% or about half of the reduction of the rye cover crop. Neither cover crop significantly reduced cumulative drainage or nitrate loads because of variability in cumulative annual drainage among plots. Both oat and rye cover crops are viable management options for significantly reducing NO3 losses to surface waters from agricultural drainage systems used for corn and soybean production. Published by Elsevier B.V.
  • Authors:
    • Van Eerd, L. L.
    • Vyn, R. J.
    • Lauzon, J. D.
    • O'Reilly, K. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 2
  • Year: 2012
  • Summary: In order to improve N best management practices in southwestern Ontario vegetable farming, the effect of cover crops on N dynamics in the fall and spring prior to sweet corn planting and during sweet corn season was assessed. The experiment was a split plot design in a fresh green pea - cover crop - sweet corn rotation that took place over 2 site-years at Bothwell and Ridgetown in 2006-2007 and 2007-2008, respectively. The main plot factor was fall cover crop type with five treatments including oat (Avena saliva L.), cereal rye (Secale cereal L.), oilseed radish (OSR; Raphanus sativus L. var. oleoferus Metzg Stokes), mixture OSR plus cereal rye (OSR&rye) and a no cover crop control. Compared with no cover crop, sweet corn profit margins were higher by $450 ha(-1) for oat at Bothwell and $1300 and $760 ha(-1) for OSR and OSR&rye, respectively, at Ridgetown. By comparing plant available N over the cover crop season, the cover crops tested were more effective at preventing N loss at Bothwell than at Ridgetown likely due to higher precipitation and sandier soil at Bothwell. Despite differences in site characteristics, cover crops did not result in increased plant available N compared with no-cover during the sweet corn season at either site, indicating that these cover crops will not provide an N credit to the following crop and growers should not modify N fertilizer applications based on cover crops.
  • Authors:
    • Mazza, G.
    • Pronyk, C.
  • Source: Bioresource Technology
  • Volume: 106
  • Year: 2012
  • Summary: Five cereal (triticale, durum wheat, CPS wheat, feed barley, oats) and two oilseed (canola, mustard) straws were fractionated with pressurized low polarity water in a flow-through reactor at 165 degrees C with a flow rate of 115 mL/min and a solvent-to-solid ratio of 60 mL/g. The conversion and extraction of the major carbohydrates and lignin from the reactor system during hydrothermal treatment was largely completed within the first 20-30 min. Glucan content of all straws were enriched by the process. More. than 90% of the xylan and nearly 50% of the lignin were extracted and there was no effect on yield due to crop species. However, there were differences in solid residue and liquid extract composition. Cereal crops yielded a residue richer in glucan and lower in lignin. Oilseed crop residues contained very low levels of ash. Xylo-oligosaccharides from oilseed crops contain more acetyl and uronic acid substituents. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
  • Authors:
    • Cai, L.
    • Padovan, B.
    • Lee, B.
    • Ren, Y. L.
  • Source: Pest Management Science
  • Volume: 68
  • Issue: 2
  • Year: 2012
  • Summary: BACKGROUND: Methyl bromide is being phased out for use on stored commodities, as it is listed as an ozone-depleting substance, and phosphine is the fumigant widely used on grains. However, phosphine resistance occurs worldwide, and phosphine fumigation requires a long exposure period and temperatures of > 15 degrees C. There is an urgent requirement for the development of a fumigant that kills insects quickly and for phosphine resistance management. This paper reports on a new fumigant formulation of 95% ethyl formate plus 5% methyl isothiocyanate as an alternative fumigant for stored grains. RESULTS: The formulation is stable for at least 4 months of storage at 45 degrees C. A laboratory bioassaywith the formulation showed that it controlled all stages of Sitophilusoryzae (L.), Sitophilusgranarius (L.), Tribolium castaneum (Herbst), Rhyzopertha dominica (F.), Trogoderma variabile Ballion and Callosobruchus maculatus (Fabricius) in infestedwheat, barley, oats and peas at 80 mg L-1 for 5 days, and in canola at both 40mg L-1 for 5 days and 80mg L-1 for 2 days at 25 +/- 2 degrees C. After an 8-14 day holding period, residues of ethyl formate and methyl isothiocyanate in wheat, barley, peas and canola were below the experimental permit levels of 1.0 and 0.1 mg kg(-1). However, fumigated oats needed an 18 day holding period. CONCLUSIONS: The findings suggest that the ethyl formate plusmethyl isothiocyanate formulation has potential as a fumigant for the control of stored-grain insect pests in various commodities. (C) 2011 Society of Chemical Industry
  • Authors:
    • Netland, J.
    • Brandsaeter, L. O.
    • Sjursen, H.
  • Source: Acta Agriculturae Scandinavica, Section B - Soil & Plant Science
  • Volume: 62
  • Issue: 2
  • Year: 2012
  • Summary: Cover crops can be used to reduce leaching and erosion, introduce variability into crop rotation and fix nitrogen (N) for use by the main crops, less is however known about effects on weeds. The effects on weed seed bank, weed growth and grain yield of 4 years of annual undersown clover and ryegrass alone and in combination, and one of the 4 years with clover or clover + grass as green manure, were studied in oat and spring wheat at two experimental sites in south-eastern Norway. These treatments were compared with no undersown crop (control) and with weed harrowing. In contrast to many results in the literature, the undersown clover in this study did not suppress annual weeds, but fertilized the weeds as well as the cereals. Undersown clover resulted in a statistically significant increase of grain yield at the two sites to 116% and 121% of control. During the 4-year period relative seed bank and density of emerged weed (dominated by Spergula arvensis) increased significantly about 4.5 and 10 times respectively in the undersown clover plots at Apelsvoll. At Kise both ryegrass alone and ryegrass mixed with clover significantly suppressed the weed biomass to 70% and 74% of control respectively. It is concluded that fertilization effects of undersown clover may have dominated and overriden the competitive effects. One whole-season clover green manure did not increase the mean yield, but resulted in a significant drop in seed bank size the following year, because of limited weed establishment in an established ley. Only a slight increase in average weed biomass was observed at one of the two experimental sites. The weed seed bank and the weed biomass were essentially kept at steady state during the experimental period in harrowed plots, but harrowing decreased grain yield significantly at both sites.
  • Authors:
    • Jeanville, P.
    • Kellog, C.
    • Schachterle, S.
    • Muntean, F.
    • Bong, S.
    • Rousetty, K.
    • Peebles, B.
    • Trengove, R.
  • Source: American Laboratory
  • Volume: 44
  • Issue: 2
  • Year: 2012
  • Authors:
    • Klakegg, O.
    • Janzen, H. H.
    • Skjelvag, A. O.
    • Bonesmo, H.
    • Tveito, O. E.
  • Source: Agricultural Systems
  • Volume: 110
  • Issue: July
  • Year: 2012
  • Summary: To increase food production while mitigating climate change, cropping systems in the future will need to reduce greenhouse gas emission per unit of production. We conducted an analysis of 95 arable farms in Norway to calculate farm scale emissions of greenhouse gases, expressed both as CO2 eq per unit area, and CO2 eq per kg DM produced and to describe relationships between the farms' GHG intensities and heir economic efficiencies (gross margin). The study included: (1) design of a farm scale model for net GHG emission from crop production systems; (2) establishing a consistent farm scale data set for the farms with required soil, weather, and farm operation data; (3) a stochastic simulation of the variation in the sources of GHG emission intensities, and sensitivity analysis of selected parameters and equations on GHG emission intensities; and (4) describing relationships between GHG emission intensities and gross margins on farms. Among small seed and grain crops the variation in GHG emissions per kg DM was highest in oilseed (emission intensity at the 75th percentile level was 1.9 times higher than at the 25th percentile). For barley, oats, spring wheat, and winter wheat, emissions per kg DM at the 75th percentile levels were between 1.4 and 1.6 times higher than those at the 25th percentiles. Similar trends were observed for emissions per unit land area. Invariably soil N2O emission was the largest source of GHG emissions, accounting for almost half of the emissions. The second largest source was the off farm manufacturing of inputs (similar to 25%). Except for the oilseed crop, in which soil carbon (C) change contributed least, the on farm emissions due to fuel use contributed least to the total GHG intensities (similar to 10%). The soil C change contributed most to the variability in GHG emission intensities among farms in all crops, and among the sensitivity elasticities the highest one was related to environmental impacts on soil C change. The high variation in GHG intensities evident in our study implies the potential for significant mitigation of GHG emissions. The GHG emissions per kg DM (intensity) decreased with increasing gross margin in grain and oilseed crops, suggesting that crop producers have economic incentives to reduce GHG emissions. (c) 2012 Elsevier Ltd. All rights reserved,