• Authors:
    • Alonso, J. C.
    • Magana, M.
    • Garcia de Leon, D.
    • Bravo, C.
    • Ponce, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 141
  • Issue: 1/2
  • Year: 2011
  • Summary: Organic farming is considered an important way to preserve biodiversity in agricultural landscapes. However, more work is still necessary to enable a full appraisal of the potential benefits of this way of farming, since studies differ in the evaluation of its effectiveness. Studies are particularly scarce in the Mediterranean region, where different climatic and ecological conditions prevent simple extrapolations from work carried out at northern latitudes. In the present study, an analysis of weed and arthropod communities was conducted in 28 pairs of organic and conventional fields in a dry cereal farmland in central Spain. Plants were identified to the species level, and arthropods to the family level. Pitfalls and sweep nets were used to sample respectively, ground-dwelling and plant-visiting arthropods. Abundance (total numbers of individuals), richness (total numbers of plant species or arthropod families), diversity (Shannon-Wiener index) and biomass (milligrams per pitfall/sweep-net) were calculated for each field and compared between organic and conventional fields using Generalized Linear Mixed Models (GLMMs). To explore the effect of predictor variables on weed richness and arthropod biomass, GLMMs were used. Organic fields showed higher abundance of weeds and arthropods (3.01 and 1.43 times, respectively), higher weed richness and diversity (2.76 and 2.33 times, respectively), and a 24% reduction in cereal plants. Arthropod diversity was lower in organic fields due to the presence of three dominant groups: Collembola, Chloropidae (Diptera), and Aphididae (Hemiptera). Weed richness increased as cereal cover decreased in organic fields. Total arthropod biomass was slightly higher in organic fields, and was affected by weed abundance and diversity. The differences between organic and conventional fields found in this study were higher than those reported for northern latitudes. This could be explained by the richer weed flora in the Mediterranean region, and a higher weed seed availability favored by the two-year rotation system typical of Iberian dry cereal farmland. We conclude that organic farming may contribute to preserve biodiversity in dryland cereal agroecosystems in the Mediterranean region.
  • Authors:
    • Yang, L.
    • Yin, S.
    • Xia, L.
    • Yu, Y.
    • Wu, D.
  • Source: PEDOSPHERE
  • Volume: 21
  • Issue: 6
  • Year: 2011
  • Summary: In the Three Gorges Area of China, soil erosion and the resultant non-point source pollution and ecological degradation have endangered agricultural ecosystems and fresh water reservoirs. Although efforts have been undertaken to reduce soil and water losses from slope land used for citrus production, information on the effects of management practices on soil fertility indices is either limited or nonexistent. This study was conducted to compare the effects of 10 years of various management practices, citrus intercropped with white clover (WC), citrus mulched with straw (SM), citrus intercropped with contour hedgerows (CH), citrus orchard land with impermeable membrane (IM), and citrus intercropped with wheat ( Triticum aestivum) and peanut ( Arachris hypogaea) (WP), as treatments on soil fertility indices with that of the conventional citrus management (CM). Results showed that the soil organic carbon, total and available nitrogen, available potassium, and water-stable aggregate (>0.25 mm) contents at the 0-5 cm depth were higher for the WC and SM treatments than the CM treatment. There was also spatial variation in soil fertility along slopes of the WC and SM treatments. The soil total and available nitrogen, phosphorus, and potassium, and water-stable aggregate (>0.25 mm) contents at both the 0-5 and 5-20 cm depths were higher for the CH and IM treatments than the CM treatment. The average soil available nitrogen and available potassium contents were higher for the WP treatment than the CM treatment, but the WP treatment had little effect on the soil organic carbon, total nitrogen, and water-stable aggregate (>0.25 mm) contents. These suggested that white clover intercropping and straw mulching were the most effective approaches to improve soil fertility in citrus orchard land of the Three Gorges area.
  • Authors:
    • Ilievski, M.
    • Spasov, D.
    • Spasova, D.
    • Atanasova, B.
  • Source: Biotechnology in Animal Husbandry
  • Volume: 27
  • Issue: 3, Book 2
  • Year: 2011
  • Summary: In the period 2005-2007 trials with five oats populations ( Krivogastani, Trebenishta, Radolishta, Bugarija, Kuceviste) and three oats varieties ( Rajac, Slavuj and Lovcen), were carried out. The trials were set up in conditions of organic and conventional production. The main objective of this investigation was to determine the differences in some morphological characteristics of the tested genotypes, which directly or indirectly affect the yield, and also, to determine the differences that came up as a result of the different systems of production (conventional and organic production). The average height of the oats plant cultivated in organic production (114,4 cm) was higher absolutely by 2,2 cm or relatively by 2.0% than the height of the oats plantcultivated in conventional production. The system of production showed no effect on the length of the panicle. The yield of oats grain by panicle in organic production (3,30 g) was higher absolutely by 0,3 g or relatively by 9.1% than the yield of oats grain by panicle in conventional production (3,0 g). The system of production did not impact significantly on the percentage of the glumes. The lowest percentage of glumes in both systems of production gave variety Rajac.
  • Authors:
    • Lenssen, A. W.
    • Sainju, U. M.
    • Jabro, J. D.
    • Evans, R. G.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 42
  • Issue: 18
  • Year: 2011
  • Summary: We evaluated the effect of no tillage (NT) and conventional tillage (CT) on soil penetration resistance (PR), bulk density (BD), gravimetric moisture content (MC), and saturated hydraulic conductivity (Ks) during the fallow phase of a spring wheat-fallow rotation. The study was conducted on two soils mapped as Williams loam at the Froid and Sidney sites. Soil measurements were made on 19 May, 23 June, and 4 August 2005 at the Froid site and on 6 June and 8 July 2005 at the Sidney site. Tillage had no effect on either soil properties except on the PR at Sidney. However, soil PR, MC, and BD varied significantly with depth regardless of tillage and location. Further, soil PR and MC varied with the date of sampling at both locations, and PR generally increased with decreased MC at all soil depths. Soil Ks was slightly influenced by tillage at both locations.
  • Authors:
    • Risaliti, R.
    • Antichi, D.
    • Barberi, P.
    • Sapkota, T. B.
    • Mazzoncini, M.
  • Source: Soil & Tillage Research
  • Volume: 114
  • Issue: 2
  • Year: 2011
  • Summary: No-tillage, N fertilization and cover crops are known to play an important role in conserving or increasing SOC and STN but the effects of their interactions are less known. In order to evaluate the single and combined effects of these techniques on SOC and STN content under Mediterranean climate, a long term experiment started in 1993 on a loam soil (Typic Xerofluvent) in Central Italy. The experimental variants are: conventional tillage (CT) and no-tillage (NT), four N fertilization rates (N0, N1, N2 and N3) and four soil cover crop (CC) types (C - no cover crop; NL - non-legume CC; LNL - low nitrogen supply legume CC, and HNL - high nitrogen supply legume CC). The nitrogen fertilization rates (N0, N1, N2 and N3) were: 0, 100, 200, 300 kg N ha(-1) for maize (Zea mays, L); 0, 60, 120,180 kg N a(-1) for durum wheat (Triticum durum Desf.); 0, 50, 100, 150 kg N ha(-1) for sunflower (Helianthus annuus L.). From 1993 to 2008, under the NT system the SOC and STN content in the top 30 cm soil depth increased by 0.61 and 0.04 Mg ha(-1) year(-1) respectively. In the same period, the SOC and STN content under the CT system decreased by a rate of 0.06 and 0.04 Mg ha(-1) year(-1) respectively. During the experimental period, N1, N2 and N3 increased the SOC content in the 0-30 cm soil layer at a rate of 0.14, 0.45 and 0.49 Mg ha(-1) year(-1). Only the higher N fertilization levels (N2 and N3) increased STN content, at a rate of 0.03 and 0.05 Mg ha(-1) year(-1). NL, LNL and HNL cover crops increased SOC content by 0.17, 0.41 and 0.43 Mg C ha(-1) year(-1) and -0.01, +0.01 and +0.02 Mg N ha(-1) year(-1). Significant interactions among treatments were evident only in the case of the N fertilization by tillage system interaction on SOC and STN concentration in the 0-10 cm soil depth in 2008. The observed SOC and STN variations were correlated to C returned to the soil as crop residues, aboveground cover crop biomass and weeds (C input). We conclude that, under our Mediterranean climate, it is easier to conserve or increase SOC and STN by adopting NT than CT. To reach this objective, the CT system requires higher N fertilization rates and introduction of highly productive cover crops. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Strickland, T. C.
    • Bosch, D. D.
    • Webster, T. M.
    • Truman, C. C.
    • Potter, T. L.
  • Source: Journal of Agricultural and Food Chemistry
  • Volume: 59
  • Issue: 14
  • Year: 2011
  • Summary: Intensive glyphosate use has contributed to the evolution and occurrence of glyphosate-resistant weeds that threaten production of many crops. Sustained use of this highly valued herbicide requires rotation and/or substitution of herbicides with different modes of action. Cotton growers have shown considerable interest in the protoporphyrinogen oxidase inhibitor, fomesafen. Following registration for cotton in 2008, use has increased rapidly. Environmental fate data in major use areas are needed to appropriately evaluate risks. Field-based rainfall simulation was used to evaluate fomesafen runoff potential with and without irrigation incorporation in a conventional tillage system (CT) and when conservation tillage (CsT) was practiced with and without cover crop residue rolling. Without irrigation incorporation, relatively high runoff, about 5% of applied, was measured from the CT system, indicating that this compound may present a runoff risk. Runoff was reduced by >50% when the herbicide was irrigation incorporated after application or when used with a CsT system. Data indicate that these practices should be implemented whenever possible to reduce fomesafen runoff risk. Results also raised concerns about leaching and potential groundwater contamination and crop injury due to rapid washoff from cover crop residues in CsT systems. Further work is needed to address these concerns.
  • Authors:
    • Kaleita, A. L.
    • Helmers, M. J.
    • Qi, Z.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 4
  • Year: 2011
  • Summary: Modification of land cover systems is being studied in subsurface drained Iowa croplands due to their potential benefits in increasing soil water and nitrogen depletion thus reducing drainage and NO(3)-N loss in the spring period. The objective of this study was to evaluate the impacts of modified land covers on soil water dynamics. In each individual year, modified land covers including winter rye-corn (rC), winter rye-soybean (rS), kura clover as a living mulch for corn (kC), and perennial forage (PF), as well as conventional corn (C) and soybean (S), were grown in subsurface drained plots in north-central Iowa. Results showed that subsurface drainage was not reduced under modified land covers in comparison to conventional corn and soybean. Soil water storage (SWS) was significantly reduced by PF treatments during the whole growing seasons and by kC during May through July when compared to the cropping system with corn or soybean only (p
  • Authors:
    • Isla, R.
    • Salmeron, M.
    • Cavero, J.
  • Source: Field Crops Research
  • Volume: 123
  • Issue: 2
  • Year: 2011
  • Summary: Under semiarid Mediterranean conditions irrigated maize has been associated to diffuse nitrate pollution of surface and groundwater. Cover crops grown during winter combined with reduced N fertilization to maize could reduce N leaching risks while maintaining maize productivity. A field experiment was conducted testing two different cover crop planting methods (direct seeding versus seeding after conventional tillage operations) and four different cover crops species (barley, oilseed rape, winter rape, and common vetch), and a control (bare soil). The experiment started in November 2006 after a maize crop fertilized with 300 kg N ha(-1) and included two complete cover crop-maize rotations. Maize was fertilized with 300 kg N ha(-1) at the control treatment, and this amount was reduced to 250 kg N ha(-1) in maize after a cover crop. Direct seeding of the cover crops allowed earlier planting dates than seeding after conventional tillage, producing greater cover crop biomass and N uptake of all species in the first year. In the following year, direct seeding did not increase cover crop biomass due to a poorer plant establishment. Barley produced more biomass than the other species but its N concentration was much lower than in the other cover crops, resulting in higher C:N ratio (> 26). Cover crops reduced the N leaching risks as soil N content in spring and at maize harvest was reduced compared to the control treatment. Maize yield was reduced by 4 Mg ha(-1) after barley in 2007 and by 1 Mg ha(-1) after barley and oilseed rape in 2008. The maize yield reduction was due to an N deficiency caused by insufficient N mineralization from the cover crops due to a high C:N ratio (barley) or low biomass N content (oilseed rape) and/or lack of synchronization with maize N uptake. Indirect chlorophyll measurements in maize leaves were useful to detect N deficiency in maize after cover crops. The use of vetch, winter rape and oilseed rape cover crops combined with a reduced N fertilization to maize was efficient for reducing N leaching risks while maintaining maize productivity. However, the reduction of maize yield after barley makes difficult its use as cover crop. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Armengot, L.
    • Berner, A.
    • Sans, F. X.
    • Maeder, P.
  • Source: Weed Research
  • Volume: 51
  • Issue: 4
  • Year: 2011
  • Summary: Conservation tillage could provide environmental benefits to organic farming. However, potential weed problems often tend to discourage farmers from adopting it. The effects of tillage (reduced vs. conventional), fertilisation (slurry vs. manure compost) and the application of biodynamic preparations (with and without) on crop yield and on weed cover, diversity and biological attributes were investigated in a cropping sequence of wheat, sunflower and spelt. Total weed cover and perennial cover in reduced tillage treatments were two to three times greater than in conventional treatments. Monocotyledon cover in reduced tillage was three times that in conventional tillage in spelt, whereas the dicotyledon Stellaria media dominated in sunflower. Weed diversity was similar across treatments, regardless of cereal crop, whereas lower diversity values were observed with reduced tillage in sunflower, because of the dominance of S. media. There was virtually no effect of fertilisation and biodynamic preparations on weed parameters. Although wheat and spelt yield decreased in reduced tillage plots (14% and 8% respectively), the sunflower grain yield was unaffected. Reduced tillage could thus be useful in organic cropping systems but would require proper management of perennial and monocotyledonous weeds, which are often problematic for annual crops.
  • Authors:
    • Negrisoli, E.
    • Crusciol, C. A. C.
    • Castro, G. S. A.
    • Perim, L.
  • Source: Planta Daninha
  • Volume: 29
  • Year: 2011
  • Summary: Tillage and other agricultural production systems can contribute to weed suppression. Thus, the objective of this study was to evaluate weed control using different grain production systems. The treatments were: I. "Harvest-fallow" System-soybean/fallow/corn/fallow/rice/fallow/soybean; II. "Harvest-green manure" System-soybean/millet/maize/pigeon pea/rice/Crotalaria/soybean; III. "Harvest-out of season" System-soy/white oats/corn/dry bean/rice/castor oil/soybean; and IV "Harvest-fodder" System-brachiaria + soy/corn + brachiaria/brachiaria + rice/soybeans. A weed survey was carried out in November 2009, after three growing seasons. A 0.3 x 0.3 m frame was randomly launched four times within each plot. The plants were identified, and the total number of weeds, dry weight, and control percentage of the species were determined according to the production system. The phytosociological analysis of the weed community was also conducted. The systems Harvest-green manure; Harvest-out of season and Harvest-fodder presented a good weed control when compared to the Harvest-fallow system. Therefore, the presence of some type of soil cover is important to maintain favorable soil characteristics and good weed control.