• Authors:
    • Cardon, G.
    • Qian, Y.
    • Dillon, M.
    • Sparks, R.
    • Barbarick, K.
    • Delgado, J. A.
    • Al-Sheikh, A.
  • Source: Soil & Tillage Research
  • Volume: 81
  • Issue: 2
  • Year: 2005
  • Summary: The potential for wind erosion in South Central Colorado is greatest in the spring, especially after harvesting of crops such as potato (Solanum tuberosum L.) that leave small amounts of crop residue in the surface after harvest. Therefore it is important to implement best management practices that reduce potential wind erosion and that we understand how cropping systems are impacting soil erosion, carbon dynamics, and properties of rangeland sandy soils. We evaluate the effects of cropping systems on soil physical and chemical properties of rangeland sandy soils. The cropping system included a small grain-potato rotation. An uncultivated rangeland site and three fields that two decades ago were converted from rangeland into cultivated center-pivot-irrigation-sprinkler fields were also sampled. Plant and soil samples were collected in the rangeland area and the three adjacent cultivated sites. The soils at these sites were classified as a Gunbarrel loamy sand (Mixed, frigid Typic Psammaquent). We found that for the rangeland site, soil where brush species were growing exhibited C sequestration and increases in soil organic matter (SOM) while the bare soil areas of the rangeland are losing significant amounts of fine particles, nutrients and soil organic carbon (SOM-C) mainly due to wind erosion. When we compared the cultivated sites to the uncultivated rangeland, we found that the SOM-C and soil organic matter nitrogen (SOM-N) increased with increases in crop residue returned into the soils. Our results showed that even with potato crops, which are high intensity cultivated cropping systems, we can maintain the SOM-C with a rotation of two small grain crops (all residue incorporated) and one potato crop, or potentially increase the average SOM-C with a rotation of four small grain crops (all residue incorporated) and one potato crop. Erosion losses of fine silt and clay particles were reduced with the inclusion of small grains. Small grains have the potential to contribute to the conservation of SOM and/or sequester SOM-C and SOM-N for these rangeland systems that have very low C content and that are also losing C from their bare soils areas (40%). Cultivation of these rangelands using rotations with at least two small grain crops can reduce erosion and maintain SOM-C and increasing the number of small grain crops grown successfully in rotation above two will potentially contribute to C and N sequestration as SOM and to the sequestration of macro- and micro-nutrients.
  • Authors:
    • Arshad, M.
    • Klein-Gebbinck, H.
    • Soon, Y.
  • Source: Canadian Journal of Plant Science
  • Volume: 85
  • Issue: 1
  • Year: 2005
  • Summary: Brown girdling root rot (BGRR) is a serious and widespread disease of canola ( Brassica rapa L.) in the Peace River region of northwestern Canada. There is no chemical control treatment for the pathogen, and farmers have observed that the disease is more severe when canola follows red fescue ( Festuca rubra L.) or clover ( Trifolium spp.) compared to summer fallow. A field study was conducted to determine how crop sequences following red fescue termination can be combined with residue and tillage management to reduce BGRR infection and increase canola yield. The five treatments consisted of rotations of: continuous canola (CCC) and oat ( Avena sativa L.)-oat-canola (OOC), both managed using reduced tillage (RT), and wheat ( Triticum aestivum L.)-wheat-canola (WWC), managed using RT, conventional tillage (CT) or no-till (NT). Canola yield followed the trend: OOC(RT)=WWC(RT) > WWC(CT) > CCC(RT)=WWC(NT). BGRR infection increased with tillage intensity: WWC(CT) > CCC(RT)=WWC(RT)=OOC(RT) > WWC(NT), and was reduced when canola followed two cereal break crops. Yield was highest when canola was preceded by a cereal crop and lowest without a break crop. The low yield with NT was attributed to poor crop emergence from a hard seed bed with unbroken turf and to competition from re-emerged fescue in the third year after fescue breaking. This study demonstrated that the cropping sequence and tillage system used influenced canola yield to a greater extent than did BGRR infection.
  • Authors:
    • Quine, T. A.
    • Djurhuus, J.
    • Heckrath, G.
    • Van Oost, K.
    • Govers, G.
    • Zhang, Y.
  • Source: Journal of Environmental Quality
  • Volume: 34
  • Issue: 1
  • Year: 2005
  • Summary: Tillage erosion had been identified as a major process of soil redistribution on sloping arable land. The objectives of our study were to investigate the extent of tillage erosion and its effect on soil quality and productivity under Danish conditions. Soil samples were collected to a 0.45-m depth on a regular grid from a 1.9-ha site and analyzed for Cs-137 inventories, as a measure of soil redistribution, soil texture, soil organic carbon (SOC) contents, and phosphorus (P) contents. Grain yield was determined at the same sampling points. Substantial soil redistribution had occurred during the past decades, mainly due to tillage. Average tillage erosion rates of 2.7 kg m(-2) yr(-1) occurred on the shoulderslopes, while deposition amounted to 1.2 kg m(-2) yr(-1) on foot- and toeslopes. The pattern of soil redistribution could not be explained by water erosion. Soil organic carbon and P contents in soil profiles increased from the shoulder- toward the toeslopes. Tillage translocation rates were strongly correlated with SOC contents, A-horizon depth, and P contents. Thus, tillage erosion had led to truncated soils on shoulderslopes and deep, colluvial soils on the foot- and toeslopes, substantially affecting within-field variability of soil properties. We concluded that tillage erosion has important implications for SOC dynamics on hummocky land and increases the risk for nutrient losses by overland flow and leaching. Despite the occurrence of deep soils across the study area, evidence suggested that crop productivity was affected by tillage-induced soil redistribution. However, tillage erosion effects on crop yield were confounded by topography-yield relationships.
  • Authors:
    • Kim,J. G.
    • Chung,E. S.
    • Seo,S.
    • Kim,M. J.
    • Chang,Y. S.
    • Chung,B. C.
  • Source: Han'gug coji hag'hoeji
  • Volume: 25
  • Issue: 3
  • Year: 2005
  • Summary: This study was conducted to determine the effect of nitrogen fertilizer levels and mixture of small grains on the productivity and quality of spring forage rape (Brassica napus) in the south region of Korea (Mokpo). The experiment was arranged in a split plot design with three replications. The main plots consisted of three different levels of nitrogen fertilizer (100, 150 and 200 kg/ha). The sub-plots consisted of five kinds of mixed small grain species (rye (Secale cereale), oat (Avena sativa), barley (Hordeum vulgare), italian ryegrass (Lolium multiflorum), and rape (B. napus) monoculture). The results were summarized as follows: (1) dry matter (DM) content of rye+rape and barley+rape mixtures increased by 2-3% compared to rape monoculture. The high level of nitrogen application increased the fresh matter yield and yield of rye+rape monoculture were higher than that of others; (2) dry matter yield of rye+rape mixture and rape monoculture with 200 kg/ha of nitrogen application were higher by 9449 and 9227 kg/ha, respectively; (3) the crude protein (CP) content of rape was high as 18.6% while average CP content was 16%. (4) The average total digestible nutrient (TDN) content showed high as 70%. It is suggested that the rye+rape mixture or rape monoculture would recommended for spring use of rape in the southern region of Korea.
  • Authors:
    • Álvaro-Fuentes, J.
    • Arrúe, J. L.
    • López, M. V.
    • Moret, D.
  • Source: European Journal of Agronomy
  • Volume: 23
  • Issue: 1
  • Year: 2005
  • Summary: Most of the benefits from conservation tillage are attained by maintaining crop residues on the soil surface. However, the effectiveness of crop residues depends on their persistence in time and maintenance of sufficient residue cover can become difficult, especially when a long-fallow period is involved. In this study, we evaluate the effects of conventional tillage (CT) and two conservation tillage systems (reduced tillage, RT, and no-tillage, NT), under both continuous cropping (CC) and cereal-fallow rotation (CF), on the dynamics of surface barley residues during four fallow periods in a dryland field of semiarid Aragon. The CC system involves a summer fallow period of 5-6 months and the CF rotation a long-fallow of 17-18 months. Results indicate that the lack of residue-disturbing operations in NT makes this practice the best strategy for fallow management. With this tillage system, the soil surface still conserved a residue cover of 10-15% after long-fallowing and percentages of standing residues ranging from 20 to 40% of the total mass after the first 11-12 months. In both CT and RT, primary tillage operations had the major influence on residue incorporation, with percentages of cover reduction of 90-100% after mouldboard ploughing (CT) and 50-70% after chiselling (RT). Two decomposition models were tested, the Douglas-Rickman and the Steiner models. Our data indicate that the Steiner model described more accurately the decline of surface residue mass over the long-fallow period in the NT plots. Measured and predicted data indicate that, under NT, 80-90% of the initial residue mass is lost at the end of fallow and that 60-75% of this loss occurs during the first 9-10 months. Finally, the mass-to-cover relationship established in this study for barley residues could be used to predict soil cover from flat residue mass through the fallow period by using a single A(m) coefficient (0.00208 ha kg(-1)). (C) 2004 Elsevier B.V. All rights reserved.
  • Authors:
    • Clayton, G. W.
    • Harker, K. N.
    • Blackshaw, R. E.
    • O'Donovan, J.
    • Maurice, D. C.
  • Source: Canadian Journal of Plant Science
  • Volume: 85
  • Issue: 4
  • Year: 2005
  • Summary: Various regression equations based on weed density alone, or relative time of weed and crop emergence or crop density in addition to weed density have been developed in western Canada to estimate the effects of wild oat (Avena fatua L.) and volunteer cereals on yield loss of field crops, and to advise farmers on the economics of weed control with herbicides. In 1997, 1998, and 1999, several of these equations were evaluated in 9 barley (Hordeum vulgare L.), 9 wheat (Triticum aestivum L.) and 11 canola (Brassica napus L.) fields in Alberta. Wild oat was the dominant weed in the barley and wheat fields, and wild oat or volunteer cereals in the canola fields. In barley and wheat, more complex equations based on both weed density and either crop density or relative time of weed and crop emergence were more reliable in estimating yield losses due to wild oat than those based on weed density alone. In canola, an equation based on volunteer barley and canola density provided the most reliable estimates. Under the assumed crop prices and herbicide costs, these equations also resulted in the best estimates of whether or not a herbicide application resulted in a net profit or loss. Herbicide application was rarely economical in barley, but usually economical in wheat and canola reflecting the different market value of the crops. The implementation of the weed economic threshold concept is likely to be more feasible in low-value crops such as feed barley than in higher-value crops such as canola.
  • Authors:
    • Spiridon, C.
    • Rotarescu, M.
    • Raranciuc, S.
    • Guran, M.
    • Popov, C.
    • Vasilescu, S.
    • Gogu, F.
  • Source: Probleme de Protectia Plantelor
  • Volume: 33
  • Issue: 1/2
  • Year: 2005
  • Summary: The paper presents the harmful organisms which attacked the field crops in 2004. It is emphasized the occurrence and spreading of the most important pathogens and harmful insects in cereals, grain legumes, industrial and fodder crops as well as their role on yield quality and quantity. In Romania, the most important issues of plant protection in 2004, by the economic impact and applied chemical measures were those determined by the following pathogens and harmful insects. The soil and seed pathogens were: Tilletia spp., Fusarium spp. in wheat; Ustilago nuda [ U. segetum var. nuda], Pyrenophora graminea in barley; Pythium spp., Fusarium spp. in maize; Sclerotinia sclerotiorum, Botrytis cinerea, Plasmopara helianthi [ Plasmopara halstedii], Orobanche cumana in sunflower; Fusarium spp., Pythium spp. in pea, beans and soyabean foliar and ear diseases were: Erysiphe spp., Septoria spp., Pyrenophora graminea, Puccinia spp., Fusarium spp. in wheat and barley; Ustilago maydis [ Ustilago zeae], Helminthosporium turcicum [ Setosphaeria turcica], Fusarium spp., Nigrospora oryzae [ Khuskia oryzae] in maize; Sclerotinia sclerotiorum, Botrytis cinerea, Alternaria spp., Phomopsis spp. in sunflower; Erysiphe spp., Septoria spp. in rape. The soil pests were: Zabrus tenebrioides, Agriotes spp. in spiked cereals; Tanymecus dilaticollis, Agriotes spp. in maize and sunflower; Delia platura in beans; Phyllotreta atra in rape and mustard; Aphthona euphorbiae in linseed; Sitona spp., Agriotes spp. in lucerne and clover. The pests which attack aerial part of plants and seeds were: Eurygaster integriceps, Lema melanopa [ Oulema melanopus], Anisoplia spp. in wheat, barley and oats; Ostrinia nubilalis, Diabrotica virgifera virgifera in maize; Thrips linarius in linseed; Athalia rosae, Meligethes aeneus, Brevicoryne brassicae in rape and mustard; Hypera variabilis [ Hypera postica], Semiothisa clathrata [ Chiasmia clathrata], Bruchophagus roddi, Subcoccinella 24- punctata in lucerne and clover. Based on evaluation of the attack potential of these harmful organisms in 2004, the potential for the future manifestation was also estimated.
  • Authors:
    • Mattsson, L.
    • Andren, O.
    • Roing, K.
  • Source: Acta Agriculturae Scandinavica Section B, Soil and Plant Science
  • Volume: 55
  • Issue: 1
  • Year: 2005
  • Summary: Estimates of soil N mineralization capacity and the factors that control the rates are necessary for optimal N management. Long-term field experiments can be used to measure how different management options affect the amount and quality of soil organic matter (SOM) - the substrate for N mineralization. Net N mineralization was estimated in a pot experiment as N uptake by ryegrass ( Lolium perenne) grown in pots with soils from 30 Swedish long-term field fertility experimental treatments ( 16 - 40 years). The long-term management effects of cereal and ley rotations, crop residue removal and return and inorganic N application on ryegrass N uptake were investigated and related to soil organic carbon (SOC) content. Total plant N uptake during three months varied between 9 and 27 mg N kg(-1) ( 23 - 67 kg N ha(-1)) and increased with SOC concentration and previous application levels of inorganic N. Soil from crop rotations with ley mineralized about 50% more N than soil from crop rotations with only cereals. Plant N uptake and SOC were not significantly affected by crop residue return.
  • Authors:
    • Abou-Alaiw, W.
    • Al-Abed, D.
    • Zhang, S. L.
    • Parani, M.
    • Chennareddy, S.
    • Sairam, R.
    • Goldman, S.
  • Source: In Vitro Cellular & Developmental Biology - Plant
  • Volume: 41
  • Issue: 4
  • Year: 2005
  • Summary: The development of robust plant regeneration technology in cereals, dicots and ornamentals that is in turn coupled to a high-frequency DNA transfer technology is reported. Transgenic cereals that include maize, Tripsacum, sorghum, Festuca and Lolium, in addition to dicots that include soybean, cotton and various ornamentals such as petunia, begonia, and geranium have been produced following either somatic embryogenesis or direct organogenesis independent of genotype. Coupled with these regeneration protocols, we have also identified several interesting genes and promoters for incorporation into various crops and ornamentals. In addition, the phenomenon of direct in vitro flowering from cotyledonary nodes in soybean is described. In in vitro flowering, the formation of a plant body is suppressed and the cells of the cotyledonary node produce complete flowers from which fertile seed is recovered. This in vitro flowering technology serves as a complementary tool to chloroplast transformation for developing a new transgenic pollen containment strategy for crop species. Recently, the center has undertaken to screen the expression response of the 24 000 Arabidopsis genes to nitric oxide. This signaling molecule upregulated 342 genes and downregulated 80 genes. The object here was to identify a population of promoters that can be manipulated by using a signaling molecule. In addition, in keeping with the mission of enhancing greenhouse profitability for North West Ohio growers, we cloned a number of genes responsive for disease resistance from ornamentals that play an important role in disease management and abiotic stress. We have constructed a plant transformation vector with CBF3 gene under the rd29A promoter for engineering cold and freezing tolerance in petunia. Leaf discs of Petunia * hybrida v26 were used for Agrobacterium-mediated transformation, and 44 hygromycin-resistant T0 plants were obtained. The presence of CBF3 gene was confirmed in all the transgenic plants by PCR and Southern analyses.
  • Authors:
    • Hanna, W. W.
    • Timper, P.
  • Source: Journal of Nematology
  • Volume: 37
  • Issue: 2
  • Year: 2005
  • Summary: Pearl millet ( Pennisetum glaucum) has potential as a grain crop for dryland crop production in the southeastern United States. Whether or not pearl millet will be compatible in rotation with cotton ( Gossypium hirsutum), corn ( Zea mays), and peanut ( Arachis hypogaea) will depend, in part, on its host status for important plant-parasitic nematodes of these crops. The pearl millet hybrid 'TifGrain 102' is resistant to both Meloidogyne incognita race 3 and M. arenaria race 1; however, its host status for other plant-parasitic nematodes was unknown. In this study, the reproduction of Belonolaimus longicaudatus, Paratrichodorus minor, Pratylenchus brachyurus, and Meloidogyne javanica race 3 on pearl millet ('HGM-100' and TifGrain 102) was compared relative to cotton, corn, and peanut. Separate greenhouse experiments were conducted for each nematode species. Reproduction of B. longicaudatus was lower on peanut and the two millet hybrids than on cotton and corn. Reproduction of P. minor was lower on peanut and TifGrain 102 than on cotton, corn, and HGM-100. Reproduction of P. brachyurus was lower on both millet hybrids than on cotton, corn, and peanut. Reproduction of M. javanica race 3 was greater on peanut than on the two millet hybrids and corn. Cotton was a nonhost. TifGrain 102 was more resistant than HGM-100 to reproduction of B. longicaudatus, P. minor, and M. javanica. Our results demonstrated that TifGrain 102 was a poor host for B. longicaudatus and P. brachyurus (Rf