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Conventional Farms (conventional + farm)
Selected AbstractsThe area requirements of an ecosystem service: crop pollination by native bee communities in CaliforniaECOLOGY LETTERS, Issue 11 2004Claire Kremen Abstract Managing ecosystem services is critical to human survival, yet we do not know how large natural areas must be to support these services. We investigated how crop pollination services provided by native, unmanaged, bee communities varied on organic and conventional farms situated along a gradient of isolation from natural habitat. Pollination services from native bees were significantly, positively related to the proportion of upland natural habitat in the vicinity of farm sites, but not to any other factor studied, including farm type, insecticide usage, field size and honeybee abundance. The scale of this relationship matched bee foraging ranges. Stability and predictability of pollination services also increased with increasing natural habitat area. This strong relationship between natural habitat area and pollination services was robust over space and time, allowing prediction of the area needed to produce a given level of pollination services by wild bees within this landscape. [source] Testing biotic indicator taxa: the sensitivity of insectivorous mammals and their prey to the intensification of lowland agricultureJOURNAL OF APPLIED ECOLOGY, Issue 1 2008Michael J. O. Pocock Summary 1Changes to agricultural policy aim to extensify agriculture and increase biodiversity. However, it is not known how sensitive many taxa are to intensification. Sensitive taxa could be used as biotic indicators, to assess changes over time and the effectiveness of policy changes. 2We sampled shrews, bats and their prey (beetles, flies and moths) on matched pairs of sites and assessed the response in their abundance to aspects of intensification: increased agrochemical inputs (using abundance on matched organic and conventional cereal fields as a proxy), the switch from hay to silage (using abundance on matched hay and silage fields) and boundary loss (using abundance in the field and near the boundary as a proxy, in cereal and grass separately). We quantified the abundance-derived sensitivity of the taxa in order to assess their use as biotic indicators. 3There was substantial variation in the sensitivity of taxa to the three aspects of intensification. Most estimates (51%) of sensitivity to boundary loss were significant, but only 8% for increased agrochemical inputs and 16% for the switch from hay to silage. Sensitivity to one aspect of intensification was not significantly related to sensitivity to another. 4Insectivorous mammals were relatively insensitive to increased agrochemical inputs and the switch from hay to silage, but strongly sensitive to boundary loss. 5Taxa with significant sensitivity to increased agrochemical inputs included some Carabidae and Diptera. We found fewer significant differences in abundance between organic and conventional farms than previous workers, probably because we controlled for boundary characteristics, suggesting that the quality of field boundaries is important in influencing biodiversity differences between organic and conventional farms. 6The switch from hay to silage had a positive effect on some Coleoptera and Diptera but a substantial negative effect on Hepialidae (Lepidoptera). 7Synthesis and applications. The recorded sensitivity of taxa to changes in agricultural practices is highly variable. Therefore, the selection of biotic indicator taxa of agricultural intensification is not straightforward. If surveys of biotic indicator taxa are used to assess the effectiveness of changes in agricultural practice, empirical evidence should be used to select suitable taxa. [source] Plant diversity and land use under organic and conventional agriculture: a whole-farm approachJOURNAL OF APPLIED ECOLOGY, Issue 4 2007R. H. GIBSON Summary 1Organic farming is thought to lead to increased biodiversity and greater sustainability than higher-yielding conventional farming systems. It is usually assumed that organic farms have both larger and higher quality areas of semi-natural habitats, although this assumption has not been unequivocally tested. 2Here we test the hypothesis that in comparison to conventional farms, organic farms have larger areas of semi-natural and boundary vegetation, and organic farms support higher levels of plant abundance, richness and diversity within cropped and semi-natural areas. 3Our study compared whole-farms: 10 organic farms were paired with 10 conventional farms in a complex landscape in the south-west of England. On average, organic farms were 7·3 years post conversion. Plant abundance, species richness and diversity were measured in all crop and non-crop landscape elements on each farm. 4Organic farms had greater total areas of semi-natural habitat (woodland, field margins and hedgerows combined). Woodland area on it's own was also significantly greater. Organic farms had more continuous blocks of woodland (with simpler perimeters than similarly sized patches on conventional farms), whereas woodland on conventional farms often consisted of more linear patches. 5Semi-natural habitats on organic farms did not have higher plant abundance, richness or diversity than their conventional counterparts. The only landscape element that showed a significant increase in plant abundance, richness or diversity was arable fields. 6Synthesis and applications. Even within a complex agricultural landscape differences do exist between organic and conventional farms, these differences being larger areas of semi-natural habitats on organic farms. However, with the exception of arable fields, no habitats on organic farms were yet of a better quality than their conventional counterparts in terms of plant abundance and diversity. Conventional farmers may be able to achieve an increase in plant diversity within arable fields by adopting some organic management practices at the field scale (e.g. exclusion of synthetic herbicides), and whole-farm conversion to organic practice might not be required. However, further work is needed to determine any biodiversity benefits of larger areas of semi-natural habitat on conventional farmland. [source] Small U.S. dairy farms: can they compete?AGRICULTURAL ECONOMICS, Issue 2009Richard Nehring Pasture-based system; Technical efficiency; Returns to scale; Dairy Abstract The U.S. dairy industry is undergoing rapid structural change, evolving from a structure including many small farmers in the Upper Midwest and Northeast to one that includes very large farms in new production regions. Small farms are struggling to retain competitiveness via improved management and low-input systems. Using data from USDA's Agricultural Resource Management Survey, we determine the extent of U.S. conventional and pasture-based milk production during 2003,2007, and estimate net returns, scale efficiency, and technical efficiency associated with the systems across different operation sizes. We compare the financial performance of small conventional and pasture-based producers with one another and with large-scale producers. A stochastic production frontier is used to analyze performance over the period for conventional and pasture technologies identified using a binomial logit model. Large conventional farms generally outperformed smaller farms using most economic measures,technical efficiency, various profitability measures, and returns to scale. [source] Phosphorus status on Canadian organic farmsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2007Ralph C Martin Abstract In eastern North America, many conventional livestock farms, especially dairy farms with high inputs of feed and fertiliser have excess soil phosphorus levels and an annual phosphorus surplus. However, a Canadian dairy farm in transition to organic, without fertiliser inputs reduced its farm P surplus to a marginal level. On long-term organic dairy farms in Ontario, most soils tested low to very low in available P as measured by a standard soil test. Canadian Prairie organic grain farms also consistently demonstrate deficiencies in available soil P. Organic producers have few viable alternatives for P management. Phosphate rock can be acceptable to organic standards (provided they are low in heavy metals, and not processed synthetically), but the P in these becomes available slowly, especially in high pH soils common on most organic farms in Canada. An alternative is to increase soil P availability. Enhanced microbial activity in organically managed soils may make P more available. Livestock manures are rich sources of available phosphorus, but a majority of organic farmers in Canada do not keep livestock. Off-farm manure sources are subject to organic regulations and hauling costs, both of which may be prohibitive. Furthermore, manure from conventional farms in Canada may be contaminated by genetically modified material from corn and soybean feed. Additional research is required to improve short-term availability of soil P and long-term replacement. Copyright © 2007 Society of Chemical Industry [source] Grain mineral concentrations and yield of wheat grown under organic and conventional managementJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2004MH Ryan Abstract On the low-P soils in southeastern Australia, organic crops differ from conventional ones primarily in the use of relatively insoluble, as opposed to soluble, P fertilisers and in the non-use of herbicides. As organic management, particularly elimination of soluble fertilisers, is often claimed to enhance grain mineral concentrations, we examined grain from wheat on paired organic and conventional farms in two sets of experiments: (1) four pairs of commercial crops (1991,1993); and (2) fertiliser experiments on one farm pair where nil fertiliser was compared with 40 kg ha,1 of P as either relatively insoluble reactive phosphate rock or more soluble superphosphate (1991 and 1992). All wheat was grown following a 2,6 year legume-based pasture phase. Both conventional management and the superphosphate treatment greatly increased yields but reduced colonisation by mycorrhizal fungi. While only minor variations occurred in grain N, K, Mg, Ca, S and Fe concentrations, conventional grain had lower Zn and Cu but higher Mn and P than organic grain. These differences were ascribed to: soluble P fertilisers increasing P uptake but reducing mycorrhizal colonisation and thereby reducing Zn uptake and enhancing Mn uptake; dilution of Cu in heavier crops; and past lime applications on the organic farm decreasing Mn availability. These variations in grain minerals had nutritional implications primarily favouring the organic grain; however, organic management and, specifically, elimination of soluble fertilisers did not induce dramatic increases in grain mineral concentrations. In addition, organic management was coupled with yield reductions of 17,84 per cent due to P limitation and weeds. The impact of large regional variations in the characteristics of organic and conventional systems on the general applicability of the results from this study and other similar studies is discussed. Copyright © 2004 Society of Chemical Industry [source] Genetic and phenotypic differences between thistle populations in response to habitat and weed management practicesBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010RICCARDO BOMMARCO Rapid evolutionary change is increasingly being recognized as commonplace, but the evolutionary consequences for species and ecosystems under human-induced selection regimes have not been explored in detail, although many species occur in such environments. In a common garden experiment and with amplified fragment length polymorphism markers, we examined whether genetic differentiation has taken place between spatially intermixed populations of creeping thistles Cirsium arvense (Asteraceae) collected from a natural habitat (maritime shores), a semi-natural habitat (road verges) and arable fields under two management regimes: conventional and organic farming. Populations of C. arvense have altered genetically and locally adapted their growth patterns with changed land use. Although plants from different habitats showed similar total biomass production, shoot and root production was higher for maritime populations, suggesting selection for increased competitive ability. Competitive ability then declined in the order semi-natural, conventional farms and organic farms. Thistles in arable fields may be more selected for tolerance against disturbances from herbicides and mechanical weed control. In addition, early shoot sprouting and genetic analysis showed differentiation between plants originating from conventional farms and farms that were converted to organic 9,30 years ago, suggesting some adaptation to altered crop cultivation practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 797,807. [source] | ||||||||||