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961.
962.
One way to disperse waste from large commercial feedlots is to spread large amounts of the waste on limited areas nearby. The effects of this practice on the soil microbial populations was assessed. Feedlot waste (FLW) was applied for 5 yr at rates of 0, 22, 67, 134, and 269 t ha?1 yr?1. Additional treatments were 538 t ha?1 yr?1 for 1 and 3 years and applications of N and NPK fertilizer. Soil cores from plots were sampled for microbial analysis before, during, and after the fifth growing season. April, July. and December soil samples were analyzed to 180-, 20-, and 480-cm depths, respectively. The following utritional and physiological groups of microorganisms were counted: soil fungi on Rose Bengal agar; bacteria on a basal mineral salts medium, on nutrient agar (both aerobically and in BBL GasPak jars), and on EMB agar (Escherichia coli-type colonies and total counts); and nitrifying and denitrifying organisms. Little effect due to FLW application rates was found, and organisms producing coliform-type colonies on EMB agar did not persist in the soil. The results indicated that applying large amounts of feedlot waste will not deleteriously affect soil microorganisms. 相似文献
963.
M.M. Mortland 《Geoderma》1980,23(3):225-226
Weathering products of Vitrandept profiles on the Kaingaroa plateau, central North Island, New Zealand, were investigated by analysis of oxalate extracts and by chemical and mineralogical analysis of clays of selected soil horizons. Comparisons were made between profiles under a Pinus radiata (D. Don) stand and profiles under an adjacent area of manuka native scrub, Leptospermum scoparium (Myrtaceae).Clay fractions (< 2 μm) of A11 horizon under pine had significantly higher SiO2/Al2O3 mole-ratios (mean SiO2/Al2O3 = 12.2) than A11 horizon under manuka (mean SiO2/Al2O3 = 7.1). No effect of vegetation on clay fractions of B horizon was evident, these clays having much lower SiO2/Al2O3 mole-ratio (1.5). Oxalate-extractable Al, Fe and Si values of < 8-mm fractions of A, B and C horizons showed no differences attributable to present vegetative cover.SiO2/Al2O3 mole-ratios of oxalate extracts increased with increasing depth, and paleosols at > 2 m depth under pine had significantly higher SiO2/Al2O3 mole-ratios in oxalate extracts (mean SiO2/Al2O3 = 2.0) than paleosols under manuka (mean SiO2/Al2O3 = 1.6). That soil horizons at > 2 m depth are in the zone of resilication is indicated by: (1) the greater SiO2/Al2O3 mole-ratios of oxalate extracts of paleosols than surface horizons; (2) lysimeter leachate composition; and (3) the presence of authigenic halloysite at > 2 m depth in soil profiles. 相似文献
964.
A turf-banked lobe with a ground soil of post-Pinedale age overlies a buried paleosol which, although thin, appears to have been developed in situ. Organic matter from the Ab horizon of the paleosol yields a radiocarbon age of BP (Gak-3823) which corresponds with the waning stages of the Pinedale Glaciation in the Rocky Mountains. Abundant kaolinite and high amounts of silt and clay suggest that it may have developed over a long time interval. 相似文献
965.
J.A. Lee 《Biological conservation》1980,18(3):238-239
966.
The theory of island biogeography supplemented with dynamic concepts from other areas of biology can be applied to a single species. Data series from mule deer Odocoileus hemonius hemonius populations inhabiting diverse mountain as well as prairie habitats were compared. The fawn-doe ratios obtained at 6 months of age were inversely correlated (r = ?0·97; p < 0·01) with ‘island’ size as indicated by the percentage of cover. Populations inhabiting small islands of cover in the prairie consistently had higher winter fawn-doe ratios than those of the relatively secure mountain habitats. Cover fragmentation and low security level of the prairi populations relates to a high annual turnover rate compared with that of the mountain populations. The impact of cover fragmentation is consistent with this interpretation of theory which pictures reproduction as annual recolonisation. This approach may be useful in predicting hunting and ecological impact effects. 相似文献
967.
R. Michael Erwin 《Biological conservation》1980,18(1):39-51
More than 80% of the beach-nesting seabirds (common tern, least tern, black skimmer, and herring gull) in coastal Virginia nest on natural barrier island beaches, while in New Jersey the vast majority nest on dredge deposition material or natural marsh islands. This contrast probably results from the differences in human disturbance in the two regions. Although 75% of all oceanfront in New Jersey allows unrestricted recreation, about 85% of the Virginia beaches are ‘protected’ under the ownership of several conservation agencies. Attendant with changes in habitat utilisation in New Jersey, competitive interactions have apparently intensified with herring gulls usurping tern and laughing gull nest sites. Other implications are discussed. 相似文献
968.
969.
970.
The complex developmental history of a paleo-argillic brown earth in Plateau Drift has been investigated using mainly micromorphological techniques. Eight kinds of pedological features are identified, quantified and related to a probable sequence of soil-forming events. Three “stable” periods of soil formation are recognised, one pre-dating emplacement of the Plateau Drift and the other two associated respectively with one or more interglacial periods between deposition of the drift and the onset of the last glaciation (Devensian) and the post-Devensian period. Clay illuviation and reduction and segregation of iron oxides are the main processes recognised in all three periods and reddening is associated with the periods before the last glaciation. Although the soil was probably subjected to several “unstable” periods only two are distinguished. The first is associated with erosion, disruption and mixing of soils and sediments, followed by transport and emplacement of the Plateau Drift. The second is related to the Devensian glaciation and is characterised by erosion, cryoturbation and deposition of loess on the eroded surface. 相似文献