• Authors:
    • Conte, O.
    • Trein, C. R.
    • Levien, R.
    • Debiasi, H.
    • Mazurana, M.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: special
  • Year: 2008
  • Summary: One of the most effective practices in preventing soil compaction is to apply stresses below the bearing capacity of the soil, often estimated by the pre-compression stress (sigma p). To evaluate the effects of cover crops and tractor traffic on σ p and compression index (CI), a field experiment was initiated in 2002 on sandy clay loam Paleudult, in Southern Brazil (Rio Grande do Sul State). Treatments under no-tillage involved winter fallow and two winter cover crops (black oats ( Avena strigosa) and black oats + vetch ( Vicia faba), which was substituted in 2006 by oilseed radish - Raphanus sativus) in the plots and two traffic conditions (with and without wheel-tractor traffic) in the subplots. Undisturbed soil cores were sampled in June and November 2006 to determine soil physical properties as well as sigma p and CI by uniaxial compression tests in an oedometer. Before oedometer tests, soil cores were equilibrated at different water tensions. Regardless of time and traffic conditions, winter fallow showed the highest sigma p value and the lowest CI value at 0.03-0.06 m. As the soil became drier, differences in sigma p between winter fallow and cover crops were reduced. In five years, seven wheel-tractor passages increased sigma p only in the surface layer (0.03-0.06 m), without altering CI. The use of cover crops and absence of traffic reduced the soil bearing capacity and increased soil susceptibility to compaction due to the reduction in soil bulk density and increase of macropores.
  • Authors:
    • Dimitrova, T.
  • Source: Herbologia
  • Volume: 9
  • Issue: 1
  • Year: 2008
  • Summary: With the purpose of studying the weed suppressive capacity of some cover crops as an alternative for weed control in lucerne ( Medicago sativa) and the effect on its productivity, a study was carried out under field non-irrigated conditions on slightly leached medium-deep chernozem. During the 2005-2007 period, a trial was carried out with the following variants: V 1 - Lucerne ( Medicago sativa), pure stand (PS) - check, zero; V 2 - Lucerne, PS - check, weeded; V 3 - Lucerne, PS - with chemical control; V 4 - Lucerne+cover oat ( Avena sativa); V 5 - Lucerne+cover spring barley ( Hordeum sativum); V 6 - Lucerne+cover rye ( Secale cereale). As a result of the study the following conclusions were drawn: In the systems of environmentally friendly agriculture, the use of some cover cereal crops (spring barley, oat and rye) in the year of establishment of lucerne stands, under favourable agro-meteorological conditions, could be an alternative to conventional technology. The cover crops had a weed suppressive capacity and as a result they decreased weed infestation degree, though to a smaller extent, as compared to chemical control. The cover crops allowed more efficient area use in the first year of lucerne cultivation, when it had a slow rate of growth and development. In spite of lower seed yields from the lucerne stands with cover crops, as compared to the pure stands by conventional technology, they are of interest in ecological aspect. Under the conditions of the concrete study, the cover crops were in the following ascending order according to aggressiveness: spring barley, oat and rye.
  • Authors:
    • Foloni, J. S. S.
    • Rosolem, C. A.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 4
  • Year: 2008
  • Summary: An earlier application of potassium fertilizer, in the cultivation of cover crop species preceding the main summer crop in no-tillage system can be an advantageous in commercial farming. This study evaluated grain yield and K accumulation in soyabean due to an earlier application of potassium fertilizer to a pearl millet cover crop, and compared to K applied at sowing of the subsequent soyabean under no-tillage. The experiment was conducted in Sao Paulo, Brazil during the 2000/2001, 2001/2002 and 2002/2003 growing seasons, on a dystroferric red Latosol (sandy loam Oxisol), cultivated with soyabean (summer) in rotation with black oats (winter) under no-till for two years prior to the experiment. Pearl millet ( Pennisetum glaucum) was sown in September over the residues of black oat ( Avena strigosa [ Avena nuda]), and soyabean ( Glycine max) was planted in the first weeks of December, in the three growing seasons. The treatments consisted of 0, 30, 60, and 90 kg/ha K 2O doses applied to pearl millet, in combination with 0, 30, 60, and 90 kg/ha K 2O applied to soyabean. Soyabean plants were harvested 25, 50, 75, and 100 days after emergence, and the grains harvested at the end of the experiment in order to determine K accumulation and yield. The early application of 60 to 90 kg/ha K 2O at pearl millet sowing did not affect K accumulation in soyabean plants. Soyabean yields were higher with applications of 80 to 90 kg/ha K 2O, which can be totally applied at pearl millet sowing. The anticipation of the application of KCl at pearl millet sowing reduced K export in soyabean grains.
  • Authors:
    • Levien, R.
    • Gamero, C. A.
    • Furlani, C. E. A.
    • Silva, R. P. da
    • Cortez, J. W.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 1
  • Year: 2008
  • Summary: To evaluate the effect of soil tillage and management of winter cover crops (black oat+radish intercrop) on the soil temperature, an experiment was conducted in a Nitossol (Alfisol) in Botucatu, state of Sao Paulo, Brazil, in the 2000 autumn/winter season. A design in randomized blocks was used in a 3*3 factorial scheme (three tillage and three cover crop managements). Soil tillage consisted of: conventional tillage, conservation tillage with chiselling, and no-tillage. The cover crops managements included plant killing with post-emergence herbicide, rolling, or shredding. The soil temperature (thermocouples) was evaluated at a depth of 5 cm, every hour, 7, 14, 30, 45, and 60 days after plant emergence; the soil water content at a depth of 10 cm, at the same dates and, the soil surface coverage (dry mass and cover index) were measured immediately after treatment application. Lower soil temperatures were observed in the no-tillage system than under conventional tillage until the 14th day after plant emergence (DAE). From the 30th DAE, the temperature was no longer influenced by the treatments due to the soil cover and sufficient water availability in the soil. The cover managements with plant rolling, shredding, or herbicide had no influence on the soil temperature. The soil temperature did not affect the development of the cover crops.
  • Authors:
    • Harrison, H.
    • Jackson, D.
  • Source: Journal of Economic Entomology
  • Volume: 101
  • Issue: 6
  • Year: 2008
  • Summary: Sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), are typically grown on bare soil where weeds and erosion can be serious problems. Conservation tillage systems using cover crop residues as mulch can help reduce these problems, but little is known about how conservation tillage affects yield and quality of sweetpotato or how these systems impact populations of beneficial and pest insects. Therefore, field experiments were conducted at the U.S. Vegetable Laboratory, Charleston, SC, in 2002-2004 to evaluate production of sweetpotatoes in conventional tillage versus a conservation tillage system by using an oat ( Avena sativa L.) (Poaceae)-crimson clover ( Trifolium incarnatum L.) (Fabaceae) killed-cover crop (KCC) mulch. The four main treatments were (1) conventional tillage, hand-weeded; (2) KCC, hand-weeded; (3) conventional tillage, weedy; and (4) KCC, weedy. Each main plot was divided into three subplots, whose treatments were sweetpotato genotypes: 'Ruddy', which is resistant to soil insect pests; and 'SC1149-19' and 'Beauregard', which are susceptible to soil insect pests. For both the KCC and conventional tillage systems, sweetpotato yields were higher in plots that received hand weeding than in weedy plots. Orthogonal contrasts revealed a significant effect of tillage treatment (conventional tillage versus KCC) on yield in two of the 3 yr. Ruddy remained resistant to injury by soil insect pests in both cropping systems; and it consistently had significantly higher percentages of clean roots and less damage by wireworm- Diabrotica-Systena complex, sweetpotato flea beetles, grubs, and sweetpotato weevils than the two susceptible genotypes. In general, injury to sweetpotato roots by soil insect pests was not significantly higher in the KCC plots than in the conventionally tilled plots. Also, more fire ants, rove beetles, and carabid beetle were captured by pitfall traps in the KCC plots than in the conventional tillage plots during at least 1 yr of the study. This study suggests that a sweetpotatoes can be successfully grown under a killed-cover crop production system.
  • Authors:
    • Nason, R.
    • Entz, M.
    • Froese, J.
    • Ranjan, R.
    • Kahimba, F.
  • Source: Applied Engineering in Agriculture
  • Volume: 24
  • Issue: 3
  • Year: 2008
  • Summary: Excess root zone soil moisture resulting from annual precipitation in excess of crop water requirements negatively affects crop yields. A field study was conducted in the 2005 and 2006 seasons on sandy loam soils to investigate the influence of berseem clover ( Trifolium alexandrium L.) cover crop in oats ( Avena sativa L.) on soil temperature, infiltration, and soil moisture redistribution within the growing season and during the fall to spring seasons. A 4-year crop rotation experiment to investigate farming with fewer chemicals was used to grow oats in a no-till cultivation system with and without the cover crop. The total and unfrozen water contents were measured in the field using neutron moisture meter and time domain reflectometry, respectively, at 0.2-m intervals from the surface to 1.8-m deep, plus a 0.1-m measurement depth. The cover crop significantly reduced soil moisture during the growing season resulting in significantly lower biomass yields (6146 kg ha -1 combined biomass for oats and berseem clover, vs. 7327 kg ha -1 for oats alone). By mid-August 2005, the cover crop treatment had 34.6% lower water content (0.17 vs. 0.26 m 3 m -3) within the 0.0- to 0.7-m root zone depth compared to the non-cover crop. During the fall, the soil profile in the cover crop treatment was 3°C warmer, thus delaying soil freezing and leading to a shallower depth of the frozen soil layer (0.4 vs. 0.6 m) in March 2006. During the spring, the cover crop treatment warmed and thawed earlier enabling more snow melt infiltration and deep percolation. Areas experiencing excess soil moisture could use annual cover crops as a means for reducing excess soil moisture during the summer growing season and avoiding accumulation of soil moisture during the fall, winter and spring seasons.
  • Authors:
    • Konopinski, M.
  • Source: Vegetable Crops Research Bulletin
  • Volume: 68
  • Year: 2008
  • Summary: Field experiments were conducted in Poland, on a grey-brown podzolic soil, to assess the yields of scorzonera ( Scorzonera hispanica cv. Einjahrige Riesen) roots in different soil and plant cultivation systems, i.e. ridge and flat cultivation, reduced soil tillage prior to sowing (shallow tillage) and the application of cover crops ( Sinapis alba, Vicia sativa, Phacelia tanacetifolia and Avena sativa) in conservation tillage and no-tillage systems. Reduced spring tillage did not have a negative effect on the yields of scorzonera roots. Cultivation of plants on ridges had a positive effect on the total and marketable yields of roots compared to flat soil cultivation. Mulching with cover crops had a significant influence on the increase in the marketable yield of roots. No-tillage cultivation did not have a negative effect on the total and marketable yields of roots. Reduction in spring tillage prior to sowing, soil mulching and no-tillage cultivation had no negative effects on the inulin content of scorzonera roots. Among the investigated cover crops, Sinapis alba was the most beneficial plant for increasing the inulin content of roots. Cultivation of plants on ridges and flat soil and reduction in spring pre-sowing tillage did not have a significant effect on the protein content of roots. Irrespective of the soil cultivation methods, a significantly higher protein content was found in the roots harvested from the plots mulched with Vicia sativa. The various plant cultivation conditions exerted a considerable influence on nutrient uptake. Roots of the plants cultivated on ridges contained higher amounts of P, K and Ca. Soil mulching created better conditions for nutrient absorption. A significant effect of Sinapis alba in increasing the P and K content of roots was also observed.
  • Authors:
    • Blecharczyk, A.
    • Maecka, I.
  • Source: Agronomy Research
  • Volume: 6
  • Issue: 2
  • Year: 2008
  • Summary: Yield, N uptake, weeds and diseases of spring barley were examined under five mulching practices (white mustard, phacelia, oat-pea mixture, straw mulch, and no mulch), three tillage systems (conventional, reduced and no-tillage) and three doses of nitrogen fertilization (0, 50 and 100 kg N ha -1). In general the grain yield of spring barley for cover crops was 10-31% higher compared with the no-mulch treatment. A mulch of straw provided a smaller barley grain yield than the no-mulch treatment. Compared to conventional tillage, grain yield under reduced tillage and no-tillage were 7 and 12% less, respectively. Spring barley sowing after a mixture of oat-pea led to decreased a negative response of reduced and no-tillage. Grain yield after treatment with legume cover crops and without N fertilization was similar compared as the rates 50 kg N ha -1 after white mustard or phacelia and as the rate 100 kg N ha -1 without mulches. There was no evidence of tillage * N fertilization interaction on grain yield, dry matter production and plant-N uptake. Cover crops and straw mulch significantly decreased total weed populations compared with the treatment without mulch. Total weed density increased from 108 plants per m 2 in the no-tillage to 322 plants per m 2 for reduced tillage, and to 416 plants per m 2 for the conventional tillage over mulch. Higher infestation of spring barley with stem base and root diseases was observed in reduced and no-tillage in comparison with the conventional soil tillage and after straw mulch and no-mulch than after cover crops.
  • Authors:
    • Ojeda Trejo, E.
    • Martinez Menes, M.
    • Prat, C.
    • Bravo Espinosa, M.
    • Medina Orozco, L.
    • Serrato Barajas, B.
  • Source: Agricultura Tecnica en Mexico
  • Volume: 34
  • Issue: 2
  • Year: 2008
  • Summary: In the upper part of Cuitzeo Lake watershed, Michoacan, Mexico, farmers use a traditional short-fallow production system. With this system, land is sown one year, and left without cultivation from one to three years for grazing. Tins system is used mainly on Andisols and Acrisols, and it is supposed to be associated with soil degradation due to low nutrient recycling level and to excessive tillage during the cultivation year. The objective of this study was to measure soil, nutrient and runoff losses under the traditional short-fallow system (AV), and under two alternatives systems: organic (O), and improved traditional (TM) systems. Research was carried out on an Acrisol in the Cointzio subwatershed, during three years under rainfed conditions on 1 000 m 2 runoff plots without replications. Results showed that soil losses under all systems were permissible (
  • Authors:
    • Bragagnolo, J.
    • Girardello, V.
    • Lanzanova, M.
    • Schneider, S.
    • Amado, T.
    • Nicoloso, R.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 4
  • Year: 2008
  • Summary: This study aimed to evaluate the efficiency of a mechanical (chisel plough) and biological (forage radish) soil decompaction method or the combination of both to improve the physical properties of a very clayey texture Oxisol and to increase soyabean grain yield under no-tillage. The treatments were: black oat on no-till (NT-O), consortium of forage radish and black oat on no-till (NT-R+O), black oat on chiselled soil (CH-O) and consortium of forage radish and black oat on chiselled soil (CH-R+O). The following properties were evaluated: soil bulk density, macroporosity, microporosity and total porosity in the layers 0-0.05, 0.05-0.10, 0.10-0.15 and 0.15-0.20 m, soil penetration resistance, soil moisture and soil water infiltration at soyabean flowering. The winter cover biomass production and soyabean yield were also measured. The treatments did not affect the soil bulk density significantly at any of the soil depths. However, the treatments NT-R+O and CH-R+O doubled the mean soil macroporosity values in the 0-0.20 m layer, with more pronounced effects in the upper soil layers. The treatments NT-R+O and CH-R+O reduced soil penetration resistance compared to NT+O, while treatment CH-O had intermediate results. The treatments NTR+O and CH-R+O increased the accumulated infiltrated water by 44.6 as compared to treatments NT-O and CH-O. The highest soyabean yields were observed in the treatment CH-R+O (3.73 tonnes/ha), which did not differ significantly from treatment NT-R+O (3.49 tonnes/ha). The effect of winter mechanical chiseling was temporary and nine months later no soil physical improvements were observed, apart from the increase of total porosity and macroporosity in the 0-0.05 m layer. Biological chiselling increased soil macroporosity, reduced soil penetration resistance and improved soil water infiltration. Mechanical chiselling was only efficient to improve the soil physical conditions when associated with biological chiselling, which prevented soil reconsolidation.