• Authors:
    • Konopinski, M.
    • Patkowska, E.
  • Source: Folia Horticulturae
  • Volume: 20
  • Issue: 2
  • Year: 2008
  • Summary: The purpose of the present study was to conduct pathogenicity tests for salsify seedlings in a soil environment colonised by selected fungi species, after the cultivation of cover crops such as oats, common vetch and tancy phacelia. A growth chamber experiment used the seeds of 'Mamut' salsify and soil overgrown with Altenaria alternata, Fusarium culmorum, F. oxysporum, Pythium irregulare, Rhizoctonia solani and Sclerotinia sclerotiorum. The pathogenicity of these microorganisms towards salsify seedlings was established on the basis of the grown plants, their health and a disease index calculated on the basis of a five-degree scale. The examined isolates considerably weakened the emergence and health of salsify. Based on pathogenicity tests, such species as R. solani, S. sclerotiorum and P. irregulare were considered as the major cause of seedling necrosis and root rot of the plants of the Tragopogon porrifolius var. sativus. Among the studied soil-borne plant pathogens, the most pathogenic ones towards salsify seedlings proved to be the isolates of R. solani, S. sclerotiorum and P. irregulare, whereas the least harmful included A. alternata and F. culmorum.
  • Authors:
    • Coelho, S.
    • Rosa, D.
    • Mauli, M.
    • Nobrega, L.
    • Piccolo, G.
  • Source: Central theme, technology for all: sharing the knowledge for development. Proceedings of the International Conference of Agricultural Engineering, XXXVII Brazilian Congress of Agricultural Engineering, International Livestock Environment Symposium - ILES V
  • Year: 2008
  • Summary: It was registered the allelopathic interference of remains of black oat (BO) in a consortium with BO, forage turnip and vetch (CO) in relation to seeds quality and soybean productivity, in interval of one, ten, twenty and thirty days between the covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing (IDS). The coverings were prepared with plots of 5*2.5 m with 1 m of border, which were desiccated according to the IDS. So, there were four treatments and one control treatment for each covering, randomized with five replications. The soybean was sown with 0.45 m among rows, thirteen lines and 14 seeds by linear meter. The productivity was determined according to water content adjusted to 13%; germination percentage; mass of 100 seeds (m-100); water content and vigor (accelerated aging test). The experimental design was completely randomized, subdivided in parcels and averages were compared by Scott and Knott test at 5% of significance. The cropped soybean under BO presented the best answer for mass of 100 seeds, but when it was cropped under CO, it had the best vigor. Productivity did not differ between BO and CO. The IDS affected m-100 and productivity. IDS, at the first day, increased m-100, but did not reduce productivity. So, it does not recommend the soybean crop near the covering desiccation.
  • Authors:
    • Rosa, D. M.
    • Mauli, M. M.
    • Nobrega, L. H. P.
    • Piccolo, G.
    • Smanhotto, A.
  • Source: Central theme, technology for all: sharing the knowledge for development
  • Year: 2008
  • Summary: It was analyzed a possible allelopathic action of black oat ( Avena strigosa Schreb) (BO) in a consortium (CO) with BO, forage turnip ( Raphanus sativus L.) (FT) and vetch ( Vicia sativa L.) (V) in relation to seedling emergency (SE), emergency speed (ES), seedling emergency speed (SES) plants heights and soybean productivity, in interval between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing (IDS). Plots of 5*2.5 m were randomly prepared with 1 m of border, four treatments of BO and CO and two control treatments, with five replications of 0.15 among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The harvest was manual and productivity was adjusted to 13% of water content. The experimental design was completely randomized, subdivided in plots. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible effect of BO and CO on SES, with higher SES to CO. The coverings did not influence on the other parameters however, IDS interfered in all of them. Thus, it is recommended CO use with IDS from ten days.
  • Authors:
    • Souza Filho, A. P. da S.
    • Nobrega, L. H. P.
    • Piccolo, G.
    • Fortes, A. M. T.
    • Uribe-Opazo, M.
  • Source: Central theme, technology for all: sharing the knowledge for development
  • Year: 2008
  • Summary: It was analyzed the possible allelopathic action of vegetal remains of black oat ( Avena strigosa Schreb) (BO) and a consortium (CO) of BO with forage turnip ( Raphanus sativus L.) and vetch ( Vicia sativa L.) in relation to the incidence of weed plants on soybean culture; in intervals (IDS) between covering desiccation with Glyphosate 480 (3 L ha -1) and the cultivar BRS 232 sowing; 5*2.5 m parcels with 1 m of border; four treatments of BO and CO and two control treatments, with five randomized replications, in August, 2006, with 0.15 m among rows. At bloom term, the plots were desiccated in an IDS, of one, ten, twenty and thirty days. The soybean was sown in November 2006, with 0.45 m among rows, thirteen sowing lines and 14 seeds by linear m -1. The incidence of weed plants was evaluated with a 0.5*0.5 m metal frame. The plants were counted and classified by narrow leaf (NL) and large leaf (LL). The soybean harvest was manual and its productivity was adjusted to 13% of water content. The experimental design was completely randomized, in split plot. The data were submitted to normality, while averages were compared by Scott and Knott test at 5% of significance. There was a possible suppressor allelopathic effect of BO and CO coverings on weed plants. The interval between desiccation and sowing interfered on weed population.
  • Authors:
    • Starkova, D. L.
    • Platunov, A. A.
  • Source: Kormoproizvodstvo
  • Issue: 8
  • Year: 2008
  • Summary: The effect of soil moisture level on development of perennial leguminous grasses in conditions of the Kirov region, Russia, is considered. The results of previous field trials revealed that the soil moisture content was higher under winter rye compared with spring crops or the absence of crops. Growing of a vetch-oat mixture for green fodder resulted in the driest soil conditions compared with oat, barley and wheat. Advantages of growing birdsfoot trefoil under the cover of cereal crops are discussed as a way of weed control, also resulting in better soil water conditions. However, birdsfoot trefoil had more light and soil moisture content and showed more intensive above-ground growth in the absence of a crop cover. Field trials were conducted to study the complex relationship between the growth and yield of spring and winter crops, availability of water and light, and weed control and production of high yield of green fodder. Data are tabulated on development and green fodder yield of birdsfoot trefoil during the 1st and 2nd years of growth without plant cover compared with growth under the cover of winter rye, barley, wheat, oat and vetch + oat in 2005 and 2006. Overall results confirmed advantages of growing birdsfoot trefoil under spring crops, especially oat, a vetch-oat mixture and wheat for higher yield of green fodder.
  • Authors:
    • Balkcom, K. S.
    • Arriaga, F. J.
    • Bergtold, J. S.
    • Stoll, M. E.
    • Price, A. J.
    • Kornecki, T. S.
    • Rap, R. L.
  • Source: Communications in Biometry and Crop Science
  • Volume: 3
  • Issue: 1
  • Year: 2008
  • Summary: Research has shown that some cover crops are allelopathic and can inhibit weed germination and growth. Additionally, negative allelopathic effects have been documented in cash crops planted into cover crop residue. However, little literature exists comparing relative the allelopathic potential of cover crops producers utilize in conservation-agriculture systems. This study assessed the effects of twelve cover crop extracts on radish ( Raphanus sativus L.) and cotton ( Gossypium hirsutum L.) radicle elongation, in three trials, using an extract-agar bioassay. In Trial 1 the cover crops were black oat ( Avena strigosa Schreb) cv. SoilSaver, crimson clover ( Trifolium incarnatum L.) cv. AU Robin, white lupin ( Lupinus albus L.) cvs. AU Homer and AU Alpha, rye ( Secale cereale L.) cv. Elbon, wheat ( Triticum aestivum L.) cv. Vigoro Grazer, and triticale (* Triticosecale Wittmack) cv. Trical 2700. In Trial 2 the cover crops were forage rape ( Brassica napus L. var. napus) cv. Licapo, sunn hemp ( Crotalaria juncea L.), Austrian winter field pea ( Pisum sativum spp. arvense L. Poir), black medic ( Medicago lupilina L.), hairy vetch ( Vicia villosa Roth), black oat cv. SoilSaver, and crimson clover cv. AU Robin. Cotton was evaluated using the same bioassay and all of the cover crops mentioned above in a single trial (Trial 3). All cover crop extracts inhibited radicle elongation compared to water. Allelopathic potential was highly variable among cultivars within a cover crop species, and within a cultivar. Allelopathic differences among cover crops give an additional weed control tool in conservation systems. However, winter cover selection may impact on cash crop performance if producers plant their crop into green residue.
  • Authors:
    • Aita, C.
    • Reichert, J. M.
    • Albuquerque, J. A.
    • Reinert, D. J.
    • Andrada, M. M. C.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 5
  • Year: 2008
  • Summary: The physical quality of a Typic Hapludalf in a no-tillage system was evaluated after the use of cover crops, and the critical limit of bulk density was measured. In autumn/winter of 1999/00 and 2000/01, the site was cultivated with black oats ( Avena strigosa) [ Avena nuda] with vetch ( Vicia sativa) and in 2001/02, with forage turnip ( Raphanus sativus). Corn ( Zea mays) was sown in summer and at the end of the cycle, four summer cover crops ( Crotalaria juncea, Cajanus cajan, Stilozobium cinereum and Canavalia ensiformis) were sown compared to fallow soil. Soil bulk density and penetration resistance were measured. The rooting system was evaluated by a root profile method during the cycle of forage turnip, corn and summer cover crops. The soil bulk density was increased by no-tillage to levels considered critical for plant growth. The root growth of all crops used in the rotations suffered some degree of restriction. There was no difference among the species in their root growth potential in the compacted soil. The root growth of the cover crop was normal up to a bulk density of 1.75 Mg/m 3, while values between 1.75 and 1.85 Mg/m 3 were restrictive, with visible deformation of the root morphology. These deformations were more pronounced when bulk density was greater than 1.85 Mg/m 3, with increased root thickening, deviations in the vertical root growth direction and concentration of roots in the topmost soil layer. The evaluated species can be used in compacted soils, but at soil bulk density >1.85 Mg/m 3, soil mobilization through mechanical methods may be necessary to alleviate the effects on root and plant growth.
  • Authors:
    • Eltz, F.
    • Rovedder, A.
  • Source: Ciencia Rural
  • Volume: 38
  • Issue: 1
  • Year: 2008
  • Summary: This study investigated the growth of Pinus elliottii and Eucalyptus tereticornis from Rio Grande do Sul, Brazil, and tested their capacity for reducing the arenization process. The treatments consisted of planting two species on: (i) arenization-degraded soil (DS); (ii) native grassland (C); (iii) native grassfield associated with cover crops (C+PC); and (iv) degraded soil associated with cover crops (DS+PC). Black oat ( Avena nuda) and Lupinus albescens were used as cover crops. The survival rate, height, basal diameter and productivity factor of tree species were obtained 30 days, 6 months and 12 months after planting. In relation to initial survival, only pine showed significant differences, with lower percentage in the treatment C+PC. Eucalyptus benefited from the consortium with cover crops, while pine presented higher sensibility to interspecific competition.
  • Authors:
    • Fares, A.
    • Ryder, M.
  • Source: Journal of the American Water Resources Association
  • Volume: 44
  • Issue: 3
  • Year: 2008
  • Summary: A study was conducted to determine the effects of three land covers (sunn hemp - Crotalaria juncea, sudex, a sorghum-sudangrass hybrid - Sorghum bicolor * S. bicolor var. sudanese, and common oats - Avena sativa) planted as vegetative filter strips on the reduction of sediment and nutrient loading of surface runoff within the Kaika-Waialua watershed on the island of Oahu, Hawaii. Runoff samples were collected and analyzed for total suspended solids (TSS), total dissolved solids (TDS), phosphorous, and three forms of nitrogen (nitrate, ammonium, total nitrogen). Study results show that during seven out of 10 runoff events, the three cover crop treatments significantly reduced TSS as compared to the fallow treatment. Average removal efficiencies were 85, 77, and 73% for oats, sunn hemp, and sudex, respectively, as compared to the fallow treatment. Nutrient concentrations were low with phosphorous concentrations, lower than 1 (g/ml) for all treatments, and total nitrogen (TN) concentrations below 7 (g/ml) except in the sunn hemp treatment, where TN concentrations were less than 10 (g/ml). Results of analysis of TDS showed that the cover crop treatments did not decrease dissolved solids concentrations in comparison with the fallow treatment. Analysis of nutrient concentrations in runoff samples did not detect any significant decreases in phosphorous, nitrogen, ammonium, or TN concentrations in comparison to the fallow treatment. However, a significant increase in TN concentrations in the sunn hemp treatment was detected and showed the nitrogen fixing capacity of sunn hemp. No treatment effects on runoff volume were detected, and runoff volumes were directly correlated with rainfall amounts showing no crops significantly impacted soil infiltration rates. These results were attributed to extremely low soil hydraulic conductivities (0.0001-7 cm/day at the soil surface, 15 and 30 cm below the soil surface). This study showed that cover crops planted as vegetative filters can effectively reduce sediment loads coming from idle and fallow fields on moderately steep volcanically derived highly weathered soils.
  • Authors:
    • Gallandt, E.
    • Reberg-Horton, S.
    • Shearin, A.
  • Source: Weed Science
  • Volume: 56
  • Issue: 3
  • Year: 2008
  • Summary: Cover crop systems were investigated in 2004 and 2005 for their effects on the activity-density (a function of movement and density) of a promising group of weed biological control organisms, the ground beetles collectively known as carabids, with particular emphasis on a beneficial carabid species Harpalus rufipes. Marked H. rufipes released into pea/oat-rye/vetch cover crop plots were more than twice as likely to be recaptured within the same plots as beetles released in nonvegetated fallow plots (18 and 8%, respectively). Marked beetles released into fallow plots were more than twice as likely to leave their plots and be recaptured in pea/oat-rye/vetch plots as vice versa (13 vs. 5%), indicating a clear preference for habitat with vegetative cover. Overall recapture rates were not different between treatments. Unmarked H. rufipes activity-density was also higher in pea/oat-rye/vetch compared to fallow plots. Additionally, five cover crop systems, including the fallow and pea/oat-rye/vetch treatments, and two residue management methods (conventional and zone tillage) were investigated from June to August in 2005 for their effects on H. rufipes activity-density. Maize was planted in 2005 into residues of the five cover crop systems grown in 2004. H. rufipes activity-density was higher in zone and conventionally tilled maize planted in pea/oat-rye/vetch residues and conventionally tilled maize planted in red clover/oat residues than in any other cover crop and residue management combination. Pea/oat-rye/vetch cover crop systems are apparently beneficial for H. rufipes during the cover crop year as well as in subsequent crops planted into this cover crop's residues. This system was not the least disturbed system but, based on the number of tillage events, represented a medium level of disturbance among the various systems. Thus, some level of disturbance might be beneficial for H. rufipes, but how and when that soil disturbance occurs requires further research to determine the best means of conserving this species.