Soils In Temperate Climates Research Articles

Developing an inventory of N 2O emissions from British soils

A spatial inventory of N 2O emissions from agricultural and non-agricultural soils in Great Britain was prepared using a simple regression model within a GIS framework. The regression model was based on published N 2O data from soils of temperate climates. It describes emissions as a function of N input ( N), water filled pore space (WFPS), soil temperature ( T s) and land use ( A): ln (N 2 O) (kgN ha −1 y −1 )=−2.7+0.60ln N (kgN ha −1 y −1 )+0.61ln WFPS (%)+0.035 T s (°C)−0.99 A . The regression model predicted the highest fluxes of 6–21 kg N ha −1 y −1 from grazed grasslands. On tilled land, predicted N 2O emissions did not exceed 6 kg N ha −1 y −1, while fluxes below 0.1 kg N ha −1 y −1 were estimated for semi-natural land. N 2O emissions from soils in spring and summer were a factor of 2–3 higher than in the remaining part of the year. Total N 2O emissions for Great Britain were estimated at 127 kt N 2O-N y −1. Distribution maps of annual and seasonal N 2O emissions outlined the areas with the largest fluxes as those of intensive livestock farming in wet western regions of Britain. The annual emissions predicted by this study were much higher for agricultural soils than those suggested by the IPCC emission factor of 1.25% (0.25–2.25%) of N input, which range between 3 and 9 kg N ha −1 y −1 for grasslands and 2 and 3 kg N ha −1 y −1 for tillage crops and predict a total emission from agricultural sources of 56 kt N 2O-N y −1. Main uncertainty of the linear regression model is caused by scaling from published short-term N 2O emission data to annual averages.

Nutrient requirements of ephemeral plant species from wet, mesotrophic soils

Abstract. Nanocyperion plant communities occur on wet, more or less nutrient‐poor and sparsely vegetated soils in temperate climates and are characterized by tiny, very shortlived plant species. Most of these have become locally extinct. It is generally assumed that drainage and eutrophication were the most important reasons for this decrease. However, chemical analysis of soil pore water from plots on growth sites of these ephemerals showed that phosphorus availability was relatively high.In a greenhouse experiment, the growth of ephemeral species was strongly limited by the amount of available phosphorus, whereas there was little or no limitation to the growth of other plant species from this habitat. At low phosphorus concentrations, the ephemeral species reached their reproductive phase within the same period, but showed a strong reduction in the amount of flowers that were produced. We concluded that ephemeral species in particular require a minimum amount of phosphorus for reproduction. Other species on nutrient‐poor, wet soils have a longer life span and can postpone flowering in nutrient‐poor soils.In contrast to other short‐lived plant species from the same habitat, the growth of ephemeral species was barely stimulated by enhanced nitrogen availability. Apparently, the ephemerals are adapted to low nitrogen concentrations. The occurrence on nitrogen‐poor and relatively phosphorus‐rich soils suggests that this community may be very sensitive to nitrogen deposition. Reduced phosphorus availability below the minimum requirements of ephemerals, for example after acidification or the exclusion of human activities, has possibly contributed to the decrease of ephemeral plant species.

Survival of Ralstonia solanacearum Biovar 2, the Causative Agent of Potato Brown Rot, in Field and Microcosm Soils in Temperate Climates

ABSTRACT After outbreaks of potato brown rot in three different fields in the Netherlands, the fate of the brown rot pathogen, Ralstonia solanacearum biovar 2, was monitored in soil by immunofluorescence colony staining (IFC) supported by R. solanacearum division-2 specific polymerase chain reaction. In selected areas of all fields, the R. solanacearum population densities were initially on the order 10(4) to 10(6) per g of topsoil. These population densities then declined progressively over time. In two fields, however, the pathogen persisted for periods of 10 to 12 months. The survival of a selected R. solanacearum biovar 2 isolate, strain 1609, in three soils, a loamy sand and two different silt loam soils, was further studied in soil microcosm experiments. The effects of temperature and soil moisture content were assessed. At 12 or 15 and 20 degrees C, a gradual decline of the population densities was observed in all three soils, from the established 10(5) to 10(6) CFU g(-1) of dry soil to significantly reduced levels, occasionally bordering the limit of detection (10(2) CFU g(-1)of dry soil), in periods of approximately 90 to 210 days. Soil type affected the rate of population decline at 20 degrees C, with the greatest decline occurring in loamy sand soil. In all three soils, the survival of IFC-detectable R. solanacearum 1609 cells at 4 degrees C was severely impaired, reflected in an accelerated decline of CFU counts, to undetectable numbers. Moreover, indications were found for the occurrence of viable but nonculturable strain 1609 cells in the loamy sand as well as in one silt loam soil under these conditions. In addition, a single freezing-thawing cycle caused a significant additional reduction of the culturable R. solanacearum 1609 populations in the three soils, though detectable populations remained. Moderate soil moisture fluctuations of approximately pF 2 did not affect the survival of R. solanacearum 1609 in soil. Severe drought, however, drastically reduced the populations of strain 1609 CFU in all three soils.

Palaeoenvironmental reconstruction of a glaciotectonized Early and Middle Pleistocene land surface, palaeosol and river sediments: Great Sampford, Suffolk, England

Glaciotectonized sediments and palaeosol at Great Sampford, western Suffolk, England are reconstructed to their original positions in order to determine the form of the original land surface and the associated soil development. The restored stratigraphy consists of Early Pleistocene Kesgrave Sands and Gravels which were deposited by the ‘pre‐glacial’ river Thames, with the Early–Middle Pleistocene Valley Farm Soil developed on a terrace surface. These units are overlain by Sampford Deformation Till and Lowestoft Till, which were formed during the Middle Pleistocene Anglian glaciation. The micromorphological features of the reconstructed soil are interpreted in terms of three climatic cycles, each comprising a period of temperate climate soil formation followed by cold climate soil disruption. The final stage of disruption is associated with the periglacial climate that preceded Anglian glacierization. This pedological reconstruction is the most complex yet recognized from British Early and Middle Pleistocene palaeosols and provides an insight into major climatic oscillations prior to the Anglian Glaciation. The surface upon which the soil developed is one of the oldest terraces of the ‘pre‐glacial’ River Thames that were formed when this river flowed northwards through East Anglia.

Phospholipid Fatty Acid (PLFA) Composition and Its Dynamics in a Desert Soil System

The effect of environmental conditions, and especially soil water content, on microbial community structure was quantified during a 15-month sampling period (1994-1995) in a Negev Desert soil system by determination of phospholipid fatty acids (PLFAs). Two rainy seasons were observed during the study period: (1) the rainy season of 1993-1994, with a total rainfall of 58mm, and (2) the rainy season of 1994-1995, with a total of 140mm, which is 55% more than the multiannual average. Soil samples collected from the 0-10cm layer exhibited changes in soil moisture and PLFA composition. Palmitic acid (nC16:0) was found to be the most common acid, with a maximum abundance found in May 1994 (27.2%). Oleic acid (C18:1 omega 9) was found to be the second highest in abundance, with high levels in January 1994 (14%), decreasing gradually to 1.3% of total ion current in January 1995. This decrease was interpreted as being caused by abiotic factors affecting the microbial community, resulting in fatty acid profile and lipid abundance. Other acids were found to be present in relatively small amounts. The iC17:1 omega 9 and C18:2 omega 8, 11 were found among the major PLFAs during the study period. The data obtained in this study were found to be similar to data obtained in soils of temperate climates, in spite of the hypothesis that the total PLFAs of the desert soil microbes are triggered and depend on soil water availability. This can afford special data interpretation of the viable biomass of the soil microbes and their metabolic status.

Morphology and adaptations of Parergodrilus Reisinger and Hrabeiella Pizl & Chalupský, two enigmatic soil‐dwelling annelids

Parergodrilus heiden Reisinger, 1925 and Hrabeiella periglan‐dulata Pizl & Chalupský, 1984 s. 1. are the only two non‐clitellate annelids which permanently inhabit the litter and humic layers of land soils in temperate climates. Their minute body size and difficulty of extraction from the substrate account for their late discovery and subsequent scanty records. Both taxa are European. Although they widely overlap in geographic and ecological distribution, they appear only remotely related. Neither Parergodrilus nor Hrabeiella displays more than a superficial resemblance to the families formerly included in the ‘archiannelids’. Since 1960 Parergodrilus has been classified with the marine interstitial Stygo‐capitella subterranea Knöllner, 1934 in the family Parergodrilidae, possibly related to some other interstitial forms or to deposit feeders of mobile bottoms. The position of Hrabeiella appears more obscure, yet very interesting in view of the many convergences (concerning the organization of the body wall musculature, pharynx, male terminalia, spermatozoal morphology) with the oligochaetes.

Phosphate speciation in excessively fertilized soil: a 31P and 27Al MAS NMR spectroscopy study

SummaryBoth P and Al MAS NMR spectra of samples of excessively fertilized sandy soil provided information about the P and Al speciation. Peak deconvolution was used to interpret reliably and quantitatively the 31P NMR spectra recorded. Most of the P was found to be associated with Al. Part of the P exhibited a chemical shift that could be attributed to octocalcium phosphate, amorphous calcium phosphate or apatite. Apatite has, however, never been reported to occur in sandy soils of temperate climates. A dithionite extraction used to remove interfering Fe from the samples also removed most of the octahedral Al‐P phase. After oxalate extraction more than 99% of the original P signal disappeared. About 7.5 to 11 % of the total oxalate extractable P of the excessively fertilized soil was present as a Ca‐P phase, even though these soils are slightly acid to acid. The estimated size of the Ca‐P phase roughly corresponds to the size of the labile P pool of these soils, as assessed in long‐term batch desorption experiments. It still remains unclear whether the labile P pool should be attributed solely to such a Ca‐P phase.

Leaching of salt from a heavy clay subsoil under simulated rainfall conditions

A considerable proportion of the water from low and high intensity applications (2 and 108 mm day t-1 falling on an unsaturated saline and sodic clay subsoil moved rapidly down through the soil profile via the macropores, and was capable of efficiently leaching salts from the unsaturated clay mass. The high efficiency of leaching indicates that saline sodic clay soils in temperate climates, such as those in the Hoo Marshes, might be more safely and more cost effectively drained by means of surface drainage systems rather than buried pipe drainage systems.

Characterization of two humic acid fractions from a calcareous vermiculitic soil: implications for the humification process

Increased soil organic matter (SOM) is associated with a reduction in K fixation by a calcareous vermiculitic soil in California. To better understand the mechanism for this effect, humic acids (HA) were extracted from this soil with and without decalcification. The HA extracted without decalcification — the mobile HA (MHA) pool — was dated as modern by 14C-dating, while the radiocarbon age of the HA bound to Ca (CaHA) was estimated at 290 yr. Compared to the MHA, the CaHA had increased aromaticity and C condensation, increased substituent carboxyl groups, and decreased substituent amino acids. Whereas MHA was evenly distributed through a 0–60 cm soil profile, the CaHA was concentrated in the 0–20 cm surface layer. The CaHA pool is probably protected from chemical and biological degradation through development of bonds to exchangeable Ca and possibly structural Fe. The MHA may be bound to the soil through exchangeable monovalent cations, through attachment of peripheral amino acids to exchange sites or fixation sites, or through other SOM molecules. No evidence was found to suggest different source materials for the two HA fractions. Although the MHA and CaHA are chemically distinct, these carbon pools may represent early and late stages of the humification process in aerated soils in temperate climates.

Nitrous oxide (N2O) emissions from soils in warm climates

N2O emission rates seem to be higher from soils in warm climates than from soils in temperate climates. Warm and moist conditions promote microbial processes that generate N2O. Clearance of tropical forests enhances N2O formation, but emission measurements from other agricultural operations in the tropics are few. Limiting fertilizer application to recommended rates applied at appropriate times and avoiding fallow land wherever practical serves to limit N2O emissions. More specific advice for agriculture in warm climates requires further studies.

Recent investigations of Pleistocene sediments near Maidenhead, Berkshire, and their archaeological content

Recent archaeological and geological assessment of Thames terrace deposits to the north of Maidenhead has been undertaken. The principal site investigated was at Furze Piatt, incorporating the important Palaeolithic localities of Cannoncourt Farm Pit and Cooper's Pit. The deposits form part of the Lynch Hill Terrace, although later sediments occur in addition to gravels deposited by the Thames. These later sediments comprise a predominantly fine-grained colluvial deposit (‘brickearth’) which is locally overlain by a tributary gravel. A temperate climate soil has been recognised in the ‘brickearth’ beneath this later gravel. Palaeolithic artefacts of predominantly Acheulian type occur within the Lynch Hill Gravel. Later artefacts, of probable Neolithic age, have been recovered from the ‘brickearth’.

Soil Response to Forest Clearing in the United States and the Tropics: Geological and Biological Factors

Twenty-six cross-sectional and time series studies of soil properties under natural forest and altered vegetation in the United States and ten tropical countries were examined to determine the changes associated with forest clearing. Organic C, total N, exchangeable Ca, Mg, and K, cation exchange capacity, available P, bulk density, and pH were considered. After forest clearing, only bulk density and available P tended to return to predearing levels. Losses of organic C, total N, and cation exchange capacity were 50 percent larger in soils developed on highly weathered parent materials in the tropics than in the same soils in the United States or in soils developed on young parent materials. Differences in soil response to clearing were related to local effects of temperature, rainfall, vegetation type, and soil acidity on organic matter decomposition. THIS STUDY TESTED THREE HYPOTHESES: 1) The removal of natural forest vegetation causes changes in soil properties; 2) changes in soil properties associated with changes in land use are long term; and 3) changes in soil properties associated with changed land use are more severe in the tropics or in soils developed on old parent materials. The study arose from the continued debate among soil scientists, ecologists, and land use planners over the adverse and beneficial effects of forest dearing, especially in developing countries in the tropics. On one side of this controversy are those who emphasize the drastic environmental changes associated with forest clearing in the tropics, frequently implying that they are irreversible (GomezPompa et al. 1972; Eckholm 1976, 1982; Myers 1976; Hecht 1982; N. J. H. Smith 1982). On the other side are those who have emphasized the variability of soils and therefore of the consequences of forest dearing (Jordan and Herrera 198 la, b), the potential for productive management of even very poor soils after deforestation (Sanchez et al. 1982), or the benefits from forest clearing, especially food production. At the heart of this debate is the question of whether soils in tropical climates respond more drastically to forest dearing than soils in temperate climates. This paper attempts to quantify the changes in soil properties that are associated with forest clearing and to identify factors associated with dramatic soil responses to clearing.

O método "Neubauer" aplicado ao estudo do potássio nos solos do estado de São Paulo

Para determinar as quantidades de elementos minerais do solo, disponíveis às plantas, pode-se lançar mão de métodos biológicos, dentre os quais se destaca o de Neubauer e Schneider. Êste método tem sido bastante empregado para solos de clima temperado. Pouco se sabe, porém, de seus resultados para os solos tropicais e subtropicais. A fim de avaliar a sua eficácia, para os nossos solos, efetuou-se uma série de experiências, cujos resultados constituem o objeto do presente trabalho. O método Neubauer foi aplicado para determinação do potássio, tendo-se utilizado o centeio e o arroz, em amostras dos quatro principais tipos de solos do Estado de São Paulo, quais sejam : Arenito Bauru, Massapé-salmourão, Terra roxa legítima e Solo humoso de baixada. Os resultados, obtidos foram comparados com os teores trocáveis de potássio, obtidos por análise química direta. Utilizando o centeio, verificou-se que a extração do potássio trocável, pela planta, variou de 83 a 114% no Arenito Bauru, de 30% a 81% no Massapé-salmourão, de 22 a 38% na Terra roxa legítima e de 52 a 84% no Solo humoso de baixada. Nos casos em que se empregou o arroz, as extrações variaram de 68 a 107% no Arenito Bauru, de 52 a 147% no Massapé-salmourão, de 4 a 76% na Terra roxa legítima e de 72 a 122% no Solo humoso de baixada. Os valores superiores a 100% significam que a planta extraiu parte do potássio, numa forma mais fixa que a "trocável". Os dados mostram que o arroz, de modo geral, apresenta uma capacidade de extração do potássio maior que o centeio. Dentre os 35 resultados médios obtidos com o centeio, em apenas 2 dêles houve uma absorção superior a 24 mg de K2O, limite êsse considerado por Neubauer e Schneider como indicador de um solo suficientemente provido de potássio. De conformidade com êsse método, 33 dos 35 resultados obtidos correspondem a solos que necessitariam de adubação potássica, fato êsse que não está de acôrdo com o que a experimentação de campo tem concluído para as diferentes culturas no Estado de São Paulo.

Some fungi isolated from pinewood soil

Twenty-one species, belonging to eleven genera, were isolated from samples of pinewood soil. Trichoderma spp. and Botrytis cinerea preponderated, followed by Penicillia and members of the Mucorales. Most of the species have been found in various soils by other investigators, and may be regarded as characteristic of acid forest soils in temperate climates. There appeared to be little or no difference between samples taken at four-inch and at ten-inch depths, the same species being present in both samples. A new species of Mortierella is described.