• Authors:
    • Goncalves, M.
    • Vitorino, A.
    • Souza, L.
    • Silva, D.
  • Source: Bragantia
  • Volume: 70
  • Issue: 1
  • Year: 2011
  • Summary: Soil physical degradation, like compaction, reduces water movement and root development. Soil structure is considered one of most importance to agriculture and closely related to it are other fundamental properties in soil-plant relationship. The objective of this study was to evaluate the effect of crop sequences on physical attributes. The research was realized in 2004/05 and 2005/06 growing seasons, in a Typic Clayey Rhodic Hopludox, under eight years of no-tillage system, at Dourados (MS). The experiment was a randomized complete block design, with three replications. Treatments were constituted by cover crops: sunflower ( Helianthus annuus L.), sunnhemp ( Crotalaria juncea L.), hairy vetch ( Vicia villosa Roth), mixture of sunnhemp+black oat ( Avena strigosa Schreb), and mixture of black oat+hairy vetch+oilseed radish ( Raphanus sativus L. Var. oliferus Metzg). Differences were not observed in soil density, porosity and aggregation rate when it was cultivated with sunflower, hairy vetch, sunnhemp, or the mixtures. Differences were observed in soil physical properties between 0-5 cm layer and 5-10 cm-10-20 cm layers, but no differences between 5-10 cm and 10-20 cm layers. Soil carbon trend to higher contents in crops with high production of surface residues, although differences in carbon contents were insufficient to modify aggregation.
  • Authors:
    • Carneiro, L.
    • Furtini Neto, A.
    • Silva, T.
    • Paludo, V.
  • Source: SEMINA-CIENCIAS AGRARIAS
  • Volume: 32
  • Issue: 4
  • Year: 2011
  • Summary: This work aimed to evaluate biomass production and phosphorus uptake by cover crops growing in two different soil types fertilized with two different sources of phosphorus. The experiment was carried out under greenhouse condition, at the Department of Soil Science, Federal University of Lavras. The experimental set up was a completely randomized design, in a 5*2*2 factorial scheme, testing five cover crops ( Brachiaria decumbens, Brachiaria brizantha cv. Marandu, Panicum maximum cv. Tanzania, Avena strigosa - oat cv. Common and Lupinus albus L. - lupine cv. Common), two P fertilizers (triple superphosphate - ST and rock phosphate araxa - FA), and two soil types (Oxisol - LVdf and Entisol - RQo), with four replications. Doses of phosphate used were 90 and 50 mg.dm -3 of P, based on the total P 2O 5 in LVdf and RQo, respectively. Plants were harvested 70 days after seedling emergence. In both soils, shoot and root biomass was higher in the ST treatment than in FNA treatment. This was probably due to the higher P accumulation in the plants. Satisfactory vegetative cover was observed when oat was cultivated using ST as a P source. For lupine, best results were obtained using FA as a P source.
  • Authors:
    • Macak, M.
    • Smatana, J.
  • Source: Acta Fytotechnica et Zootechnica
  • Volume: 14
  • Issue: 2
  • Year: 2011
  • Summary: The research of crop rotation pattern and field homogenization was carrying out during 2000-2010 at company Agrokarpaty Plavnica Ltd in Slovakia. The average temperature of the site during growing period is 14.9degreesC and a sum of precipitation 438 mm. The fields are situated at 300-450 m above the see level. Total acreage of arable land is 380 ha. Share of medicinal plants varied from 85 ha to 145 ha during evaluated period. The main growing medicinal and spices plants are as follows: Galega officinalis L, Medicago sativa L, Hypericum perforation L, Mentha piperita L, Melissa officinalis L, Calendula officinalis L, Fagopyrum esculentum Moench, Carum carvi L., Achilea milefolium L, Agrimonia eupatoria L, Matricaria recutita L, Plantago lanceolata L, Malva mauritiana L. As a forecrop red clover ( Trifolium pratense L), winter wheat ( Triticum aestivum L), spring barley ( Hordeum sativum L.) and oat ( Avena sativa L.) have been growing. The management practices of "Agrokarpaty Plavnica" are in full compliance with the good agricultural practices (GAP). The high priority is maintenance of soil fertility and sustain of nutrients, mainly nitrogen. The green manure, cover crop, growing of legumes and compost from own productions are used. Two steps for designing have been suggested (i) Field consolidation and homogenisation of field for crop rotations area, (ii) Proposal of crop rotation pattern. The interested area is characterized by low production potential of 8 classes of soil production categories. We have proposed new cropping pattern of 14 fields with total acreage of 180.11 ha with average field 12.87 ha. Share of medicinal and spices plants is 68.27%, share of red clover 14.29% and spring cereals 17.46%. The design of propose crop rotation allows to use organic manure mainly before medicinal plants growing for leaves drug, and incorporation of cover crops for maintenance of soil fertility. Supposed crop rotation pattern complies with basic principles of crop rotation and sustainable agriculture.
  • Authors:
    • Pereira, D. C. de
    • Fortes, A. M. T.
    • Spiassi, A.
    • Senem, J.
    • Tomazoni, D.
  • Source: SEMINA-CIENCIAS AGRARIAS
  • Volume: 32
  • Issue: 2
  • Year: 2011
  • Summary: In agricultural crops is common planting the main crop on the remains of straw harvesting the crop earlier due to no-tillage system. The straw remaining in the soil can exert positive or negative influence on the main crop through the release of organic compounds that carry allelopathy on plants of the subsequent growing. This experiment consisted of mixing and blending of different types of turnip ( Brassica rapa L.), oats ( Avena sativa L.), crambe ( Crambe abyssinica Hochst. Ex RE Fries), Safflower ( Carthamus tinctorius L.) and rapeseed ( Brassica napus L. var) in soil and placed in plastic trays where they planted the seeds of maize. The experimental design was completely randomized design with six treatments and three repeticoes. As ratings were: emergence, rate of emergence, shoot length, root length, root dry weight, dry weight of shoots. The cover crops canola and safflower showed a positive effect, as crambe, turnips and oats had a negative effect on initial growth of maize seedlings, are not suitable for cover crop to maize sowing.
  • Authors:
    • Ichiyama, K.
    • Jitsuyama, Y.
    • Iwama, K.
    • Uchino, H.
    • Sugiura, E.
    • Yudate, T.
  • Source: Plant Production Science
  • Volume: 14
  • Issue: 1
  • Year: 2011
  • Summary: The use of cover crops is an effective technique to control weeds, which are one of the most serious problems for crop production without using herbicides. This study investigated the characteristics of cover crops for weed suppression at an organic farming field in a snowy-cold region, Hokkaido. Nine, three and two species of cover crops comprising both Poaceae and Leguminosae were grown in 2003, 2004 and 2005, respectively, at different sowing densities from 50 to approximately 4000 seeds m -2. The relationships between weed dry matter production and characteristics of cover crops, such as plant height and coverage, were investigated at 4 and 10 weeks after cover crop sowing (WAS). Correlation analysis of the weed dry weight with characteristics of cover crops revealed that the cover crop coverage at 4 WAS had a strong and stable effect on weed suppression. The cover crop coverage at 4 WAS was affected primarily by their seed weight when cover crops with a large variation in seed weight were used, and by the sowing density when cover crops with a small variation in seed weight were used. These results suggest that to achieve high weed suppression it is important to obtain higher coverage at the early growth stage of the cover crops with a heavy seed weight and high sowing density.
  • Authors:
    • Muys, B.
    • Hermy, M.
    • Govers, G.
    • Pina, A.
    • Valckx, J.
  • Source: Pedobiologia
  • Volume: 54
  • Issue: Supplement 1
  • Year: 2011
  • Summary: Some of the widely used cover crops in temperate agroecosystems (including species of the Brassicaceae and Poaceae) have been shown to exhibit allelopathic effects. In particular, various Brassicaceae have been reported to act as biofumigants against a variety of soil-borne pests through the release of i.a. isothiocyanates (ITC) from glucosinolate precursors. Although these allelochemicals may potentially reduce the need for application of synthetic pesticides, their effects on beneficial soil ecosystem engineers such as earthworms (Lumbricidae) have not been assessed yet. Food choice chambers were used to assess short-term food preferences of Lumbricus terrestris L. for lacy phacelia ( Phacelia tanacetifolia BENTH.), the Poaceae Italian ryegrass ( Lolium multiflorum LAM.) and oats ( Avena sativa L.), and the Brassicaceae yellow mustard ( Sinapis alba L.) and rapeseed ( Brassica napus L.) while litter bags were used to study long-term litter preference under field conditions. Habitat preference of L. terrestris was determined through simple habitat preference units. Ryegrass residues were a preferred food resource, both in fresh and partly decomposed state, over mustard, phacelia or rapeseed residues, and these were in turn more fed on than oats. Litter disappeared at a fast and variable rate from litter bags under field conditions. No clear relationships with residue C:N ratio were observed. Habitats in which living oat plants were present were avoided in comparison to habitats with bare soil or yellow mustard plants. In conclusion, brassicaceous cover crops are not preferred nor avoided by L. terrestris compared to the other cover crops in this study. Decreased ITC release and earthworm exposure under field conditions may further lower the risk of harmful effects, but further research on the long-term impact is needed.
  • Authors:
    • Altieri, M. A.
    • Lana, M. A.
    • Bittencourt, H. V.
    • Kieling, A. S.
    • Comin, J. J.
    • Lovato, P. E.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 8
  • Year: 2011
  • Summary: In Santa Catarina, southern Brazil, family farmers modified the conventional no-till system by flattening cover crop mixtures on the soil surface as a strategy to reduce soil erosion and lower fluctuations in soil moisture and temperature, improve soil quality, and enhance weed suppression and crop performance. During 2007 and 2008, we conducted three experiments aimed at understanding the processes and mechanisms at play in successful organic conservation tillage systems (OCT), especially the underpinnings of ecological weed suppression, a key advantage of OCT systems over conventional no-till systems. Our results, as well as farmers observations, suggest that cover crops can enhance weed suppression and hence crop productivity through physical interference and allelopathy and also a host of effects on soil quality, fertility, and soil moisture that we did not measure. Results from the three trials indicate that the best cover crop mixture should include a significant proportion of rye, vetch, and fodder radish as these mixtures produce large biomass, and are readily killed by rolling forming a thick mulch sufficient to provide effective weed control in the subsequent vegetable crop.
  • Authors:
    • Alletto, L.
    • Coquet, Y.
    • Justes, E.
  • Source: Agricultural Water Management
  • Volume: 102
  • Issue: 1
  • Year: 2011
  • Summary: Effects of two tillage treatments and two fallow period managements under continuous maize cropping on soil temperature, soil water dynamics and maize development were evaluated over a 4-year period (2005–2008). Tillage treatments were conventional tillage with mouldboard ploughing and conservation tillage with disk harrowing. The fallow period managements were bare soil or soil sown with a cover crop after maize harvest. For each year, topsoil temperature (0–20 cm-depth) was lower under conservation tillage systems at sowing, from 0.8 to 2.8 °C. This difference persisted several weeks after sowing, and disappeared afterwards. Under conservation tillage, higher soil water content was generally measured at sowing and during the growing season strong fluctuations were observed at 40 cm-depth. Under conventional tillage, soil water content varied mainly in the tilled layer (20 cm-depth). Tillage and fallow period management affected water flow rate at 40 cm-depth. During the maize growing season, the lowest drainage volumes were measured in 2006 and 2008 under conservation tillage in cover cropped plots. No effect of fallow period management on maize development and yield was observed but significantly higher yields were measured under conservation tillage in 2005 and 2007. From this 4-year experiment under continuous maize cropping, using cover crop and reducing tillage intensity enhanced water use efficiency while maintaining or increasing maize yields.
  • Authors:
    • Blanco-Canqui, H.
    • Mikha, M. M.
    • Presley, D. R.
    • Claassen, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Inclusion of cover crops (CCs) may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no-till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near-surface bulk density (rho b) by 4% and increased cumulative infiltration by three times relative to no-CC plots. Without N application, SH and LMS reduced Proctor maximum rho b, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no-CC plots in the 0- to 7.5-cm depth. The CC-induced increase in SOC concentration was negatively correlated with Proctor maximum rho b and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no-till systems improved soil physical properties, and the CC-induced change in SOC concentration was correlated with soil physical properties.
  • Authors:
    • Calonego, J. C.
    • Rosolem, C. A.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Soil water availability to plants is affected by soil compaction and other variables. The Least Limiting Water Range (LLWR) comprises soil physical variables affecting root growth and soil water availability, and can be managed by either mechanical or biological methods. There is evidence that effects of crop rotations could last longer than chiseling, so the objective of this study was to assess the effect of soil chiseling or growing cover crops under no-till (NT) on the LLWR. Crop rotations involving triticale (X Triticosecale) and sunflower (Helianthus annuus) in the fall-winter associated with millet (Pennisetum glaucum), sorghum (Sorghum bicolor) and sunn hemp (Crotalariajuncea) as cover crops preceding soybean (Glycine max) were repeated for three consecutive years. In the treatment with chiseling (performed. only in the first year), the area was left fallow between the fall-winter and summer crops. The experiment was carried out in Botucatu, Sao Paulo State, Brazil, from 2003 to 2006 on a Typic Rhodudalf. The LLWR was determined in soil samples taken from the layers 0-20 cm and 20-40 cm, after chemical desiccation of the cover crops in December of the first and third year of the experiment. Chiseling decreases soil bulk density in the 0-20 cm soil layer, increasing the LLWR magnitude by lowering the soil water content at which penetration resistance reaches 2.0 MPa; this effect is present up to the third year after chiseling and can reach to a depth of 0.40 in. Crop rotations involving sunflower + sunn hemp, triticale + millet and triticale + sunn hemp for three years prevented soil bulk density from exceeding the critical soil bulk density in the 0-0.20 in layer. This effect was observed to a depth of 0.40 m after three years of chiseling under crop rotations involving forage sorghum. Hence, chiseling and some crop rotations under no tillage are effective in increasing soil quality assessed by the LLWR.