Subsoil Level Research Articles

Spatially resolved soil solution chemistry in a central European atmospherically polluted high-elevation catchment

Abstract. We collected soil solutions by suction lysimeters in a central European temperate forest with a history of acidification-related spruce die-back in order to interpret spatial patterns of soil nutrient partitioning, compare them with stream water chemistry and evaluate these parameters relative to concurrent loads of anions and cations in precipitation. Five lysimeter nests were installed in the 33 ha U dvou loucek (UDL) mountain catchment at different topographic positions (hilltops, slopes and valley). Following equilibration, monthly soil solution samples were interrogated over a 2-year period with regard to their SO42-, NO3-, NH4+, Na+, K+, Ca2+, Mg2+ and total dissolved Al concentrations, organic carbon (DOC) and pH. Soil pits were excavated in the vicinity of each lysimeter nest to also constrain soil chemistry. For an estimation of phosphorus (P) availability, ammonium oxalate extraction of soil samples was performed. Cation exchange capacity (CEC ≤58 meq kg−1) and base saturation (BS ≤13 %) were found to be significantly lower at UDL than in other monitored central European small catchments areas. Spatial trends and seasonality in soil solution chemistry support belowground inputs from mineral-stabilized legacy pollutants. Overall, the soil solution data suggest that the ecosystem was still chemically out of balance relative to the concurrent loads of anions and cations in precipitation, documenting incomplete recovery from acidification. Nearly 30 years after peak acidification, UDL exhibited similar soil solution concentrations of SO42, Ca2+ and Mg2+ as median values at the Pan-European International Co-operative Program (ICP) Forest sites with similar bedrock lithology and vegetation cover, yet NO3- concentrations were an order of magnitude higher. When concentrations of SO42-, NO3- and base cations in runoff are compared to soil pore waters, higher concentration in runoff points to lateral surficial leaching of pollutants and nutrients in excess than from topsoil to subsoil. With P availability being below the lowest range observed in soil plots from the Czech Republic, the managed forest ecosystem in UDL probably reflects growing inputs of C from regenerating vegetation in the N-saturated soil, which leads to P depletion in the soil. In addition, the observed spatial variability provides evidence pointing to substrate variability, C and P bioavailability, and landscape as major controls over base metal leaching toward the subsoil level in N-saturated catchments.

Sulfur deposition still contributes to forest soil acidification in the Pearl River Delta, South China, despite the control of sulfur dioxide emission since 2001.

Sulfur dioxide emissions have been regulated at a global scale; sulfur (S) deposition no longer contributes to soil acidification instead of an alleviation effect in temperate regions; however, it remains unclear whether S deposition still contributes to soil acidification in the tropics. The Pearl River Delta (PRD), South China, has been suffering serious soil acidification, but the contribution of S deposition was ignored because of the regulation of S emission since 2001. Here, we chose the evergreen broadleaf forests, which are the typical forest type at the regional scale in PRD to examine the contribution of S deposition and its characteristics in this acidification, based on an established urban-rural gradient in the range of 260km. A substantial acidification was evidenced by the significant decline of soil pH from rural to urban sites, with mean pH values decreased by more than 0.60U through the whole 40-cm depths. However, there was no significant difference in soil pH from 0-10cm, 10-20cm, and to 20-40cm at each site (P > 0.05). Acid-neutralizing capacity (ANC) showed a similar trend to soil pH, with a significant decline along the urbanization gradient and no significant effect of soil depths. Soil sulfate (SO42-), as the most abundant species in ANC, contributed greatly to soil acidification for the whole 40-cm depth, as shown by the significant positive relationships between it with soil pH and base cations. Soils also exhibited the depletion of base cations with low base saturation (< 20%) and the release of Al and Fe. Our research demonstrated that the severe soil acidification in the PRD region has extended to the subsoil level (40-cm depth), and S deposition is still an important driver to this acidification. Therefore, both recovering the acidified soils and controlling the acidifying pollutants, especially S, are particularly difficult in southern China.

Agricultural soil organic carbon stocks in the north-eastern Iberian Peninsula: Drivers and spatial variability

Estimating soil organic carbon (SOC) stocks under agriculture, assessing the importance of their drivers and understanding the spatial distribution of SOC stocks are crucial to predicting possible future SOC stocks scenarios under climate change conditions and to designing appropriate mitigation and adaptation strategies. This study characterized and modelled SOC stocks at two soil depth intervals, topsoil (0–30 cm) and subsoil (30–100 cm), based on both legacy and recent data from 7245 agricultural soil profiles and using environmental drivers (climate, agricultural practices and soil properties) for agricultural soils in Catalonia (NE Spain). Generalized Least Square (GLS) and Geographical Weighted Regression (GWR) were used as modelling approaches to: (i) assess the main SOC stock drivers and their effects on SOC stocks; (ii) analyse spatial variability of SOC stocks and their relationships with the main drivers; and (iii) predict and map SOC stocks at the regional scale. While topsoil variation of SOC stocks depended mainly on climate, soil texture and agricultural variables, subsoil SOC stocks changes depended mainly on soil attributes such us soil texture, clay content, soil type or depth to bedrock. The GWR model revealed that the relationship between SOC stocks and drivers varied spatially. Finally, the study was only able to predict and map topsoil SOC stocks at the regional scale, because controlling factors of SOC stocks at the subsoil level were largely unavailable for digital mapping. According to the resulting map, the mean SOC stock value for Catalan agriculture at the topsoil level was 4.88 ± 0.89 kg/m2 and the total magnitude of the carbon pool in agricultural soils of Catalonia up to 30 cm reached 47.9 Tg. The present study findings are useful for defining carbon sequestration strategies at the regional scale related with agricultural land use changes and agricultural management practices in a context of climate change.

Определение оптимальных показателей продуктивности агроэкосистем в условиях Ленкоранской низменности Азербайджана

The real and prognosticated dimensions of the farming lands productivity under natural agroecosystems in the Lankaran lowland condition have been defined. It was determined that the soil, climate, subsoil level and other factors of the landscape influence on the farming land productivity under the Lankaran Lowland condition. The productivity of cereals on these soils is 45.2 centner/ha, vegetables 318.2 centners per hectare, tea 81.2 centners per hectare, fruit 62.1 centner/ha. With the implementation of agroecological measures to increase the fertility of yellow–meadow soils, it is optimal to forecast cereals for 48.2 centners/hectare, 323.2 centner /ha for vegetables, 85.4 hectares for tea, and 66.2 centners per hectare for fruit. The lowest productivity in the hydromorphicallyholophytefacies groups of soil formation, in the soils of the given facies group, the productivity of wheat is 29.0...18.3 centner/ha, vegetables 214.3...99.1 centner / ha, natural fodder for air–dry weight of 19.2...4.1 c/ha. Soils related to the facies group of hydromoric-holophytic soil formation are characterized by low scores, which is explained with unfavorable conditions of formation on the one hand and high toxicity of readily soluble salts on the other hand. In order to reduce the concentration of salts along the soil profile on the territory of the research object, it is proposed to use agro-meliorative measures, taking into account the landscape parameters and the physico-chemical agro-meliorative and physico-mechanical properties of soils. In addition, in connection with the purpose of lowering the level of groundwater in the direction of the Caspian Sea, it is necessary to conduct a main drainage and collector system, on the basis of which the main part of the salts accumulated in the soil will be removed.

Organic matter in temperate cultivated floodplain soils: Light fractions highly contribute to subsoil organic carbon

Floodplain soils are important reservoirs of organic carbon (OC) in the terrestrial carbon cycle. Few rivers and floodplains in the world and particularly in central Europe are in a natural state. They are regulated, stabilised from erosion behind artificial levees, drained and used for agriculture. Fluvisols store high amounts of OC from the topsoil to the subsoil, but little is known about the soil organic matter (SOM) quality and its vulnerability to decomposition. In this study, two regulated floodplains originating from different parent materials under grassland use in Southern Germany (Alpine Foreland and the Bavarian Forest) were sampled and analysed for the quantity and quality of inherent SOM in the topsoil and two subsoil levels. We characterised bulk soil (pH, texture, inorganic carbon and total nitrogen) and applied a combined density and size fractionation scheme to obtain six fractions. The chemical composition of the fractions was further determined using solid-state 13C NMR spectroscopy (SOM composition), as well as X-ray diffraction (clay mineralogy) and N2-BET (specific surface area (SSA)). Contributions of light fractions and especially of occluded particulate organic matter (oPOMfine) to the total OC were remarkably high in the subsoils. Organo-mineral associations (OMFfine) highly contributed to total OC at both sites but only in the topsoils. The highest OC concentrations of OMFfine were found in calcareous parent material, which shows that polyvalent cations promote OC storage. However, the inter-site as well as intra-site heterogeneity of oPOMfine and OMFfine OC contribution was highly variable. In the Bavarian Forest, oPOMfine was enriched in lipids in the subsoil. This was most probably due to a limited supply of oxygen in the aggregates through fluctuating groundwater levels that retarded decomposition and selectively preserved aliphatic compounds. In the Alpine Foreland, soil biota had mixed fresh SOM into the subsoil. There, oPOMfine contained all the functional C-groups, particularly carbohydrates. A changing global climate jeopardises OC reservoirs in floodplains, due to increased flooding and associated river bank erosion. Such disturbances not only cause losses of productive land but also release OC stored in light fractions that could be oxidised to CO2, depending on its chemical composition, thus adding to global warming.

Towards an operative use of remote sensing for exploring the past using satellite data: The case study of Hierapolis (Turkey)

Abstract This paper is focused on the presentation and discussion of an object oriented approach, applied to the Hierapolis (Turkey) site, to automatically detect the subtle features linked to buried archaeological remains. The data processing is applied twice: (i) first, globally at the whole image and, (ii) second, at the significant subsets identified by global analysis, in order to refine the previously obtained categorization. Object oriented approaches are usually based on two main steps: i) first the segmentation, ii) then the classification. Herein, we first performed the unsupervised classification step and, then, the segmentation. This choice is given by the specificity of archaeological issue, in particular: (i) the subtle features/targets to be identified are partially or totally unknown and characterized by a very small spectral separability from the background, and therefore (ii) the discrimination between archaeological class and substrates likely suffers significant confusion. To cope with these issues, the first step is based on an unsupervised classification, which provides a first ‘rough’ categorization of pixels; the second step, based on the segmentation, enables us to extract the geometric shape, and, in turn, to only categorize as archaeological class those pixels belonging to geometrically (rectangular and linear) shaped clusters. Outputs from this classification identify rectangular and linear features of archaeological interest whose size suggested that they may be a farm and some sectors of an aqueduct, respectively. Results from satellite based analysis were successfully evaluated by georadar and geomagnetic prospection along with field survey. From georadar and geomagnetic prospection we were able i) to confirm the presence of buried remains and ii) to detail and characterize these archaeological features at the subsoil level as well as to define the local stratigraphy. From field survey we dated the detected buried remains to a period spanning from Imperial Roman to early Byzantine historical times.

Structural sustainability of cambisol under different land use system

Incongruous management techniques have been associated with some significant loss of agricultural land to degradation in many parts of the world. Land degradation results in the alteration of physical, chemical and biological properties of the soil, thereby posing a serious threat to sustainable agricultural development. In this study, our objective is to evaluate the changes in a Cambisol structure under six land use systems using the load bearing capacity model. Sampling was conducted in Amazonas Region, Brazil, in the following land use: a) young secondary forest; b) old secondary forest; c) forest; d) pasture; e) cropping, and f) agroforestry. To obtain the load bearing capacity models the undisturbed soil samples were collected in those land use systems and subjected to the uniaxial compression test. These models were used to evaluate which land use system preserved or degraded the Cambisol structure. The results of the bulk density and total porosity of the soil samples were not adequate to quantify structural degradation in Cambisol. Using the forest topsoil level (0-0.03 m) as a reference, it was observed that pasture land use system was most severe in the degradation of the soil structure while the structure were most preserved under old secondary forest, cropping system and forest. At the subsoil level (0.10-0.13 m depth), the soil structure was most degraded in the cropping land use system while it was most preserved in young secondary forest and pasture. At the 0.20-0.23 m depth, soil structure degradation was most severe in the old secondary forest system and well preserved in young secondary forest, cropping and agroforestry.

Root Distribution of Drought‐Resistant Peanut Genotypes in Response to Drought

AbstractThe ability of a plant to modify its root distribution to exploit deeper stored soil water may be an important mechanism to avoid drought. This study aimed at assessing root distributions, variations in root length density (RLD) and percentage of root distribution, and the relevance of root traits for yield of drought‐resistant peanut genotypes under different available soil water levels. The experiment was conducted in the dry season during the years 2003/04 and 2004/05. Eleven peanut genotypes (ICGV 98300, ICGV 98303, ICGV 98305, ICGV 98308, ICGV 98324, ICGV 98330, ICGV 98348, ICGV 98353, Tainan 9, KK 60‐3 and Tifton‐8) and three soil moisture levels [field capacity (FC), 2/3 available soil water (AW) and 1/3 AW] were laid out in a split‐plot design with four replications. Roots were sampled by a core sampler at 37, 67 and 97 days after sowing (DAS). Root length was determined by a scanner and the WINRHIZO Pro 2004a software. RLD was calculated as the ratio of root length (cm) and soil volume (cm3). Graphical illustration of root distribution was constructed by merging RLD in the first and second soil layers (0–40 cm) as upper roots and pooling RLD at the third, fourth and fifth layers (40–100 cm) as lower roots. Pod yield, biomass and harvest index (HI) were recorded at harvest. A drought tolerance index (DTI) was calculated for each parameter as the ratio of the parameter under stress treatment to that under well‐watered conditions. Variations in RLD in 40 to 100 cm layer (RLD40 to 100 cm) were found under well‐watered conditions, and the peanut genotypes could be readily identified as high, intermediate and low for this trait. Changes in RLD in the 40 to 100 cm soil layer were found at 2/3 AW and were more evident at 1/3 AW. ICGV 98300, ICGV 98303, ICGV 98305, ICGV 98308 and KK 60‐3 were classified as drought responsive as they increased RLD in the deeper subsoil level in response to drought. In general, RLD under drought conditions was not related to biomass production. The ability to maintain the percentage of RLD (DTI for %RLD) was related to pod yield, DTI for pod yield and DTI for HI. ICGV 98300, ICGV 98303, ICGV 98305 exhibited high DTI (RLD40 to 100 cm) which may explain their high pod yield, DTI (PY) and DTI (HI). Based on these observations we classified them as drought‐avoiding genotypes.

Os primeiros passos da Arqueologia da Arquitectura no âmbito do Instituto Português do Património Arquitectónico

Pretende-se, com este texto, traçar o percurso dos primeiros passos da afirmação da Arqueologia da Arquitectura no âmbito do Instituto Português do Património Arquitectónico (IPPAR), instituição a quem cabe a missão de preservar, salvaguardar e valorizar o património arquitectónico nacional. De facto, é possível constatar que, infelizmente, o conhecimento e a aplicação desta disciplina não só no IPPAR como em Portugal não teve ainda a divulgação necessária. Podemos afirmar que esta situação resulta não só de um desconhecimento geral da disciplina, como da situação algo peculiar da falta de interesse da maioria dos arquitectos portugueses pelas matérias relacionadas com o restauro arquitectónico. Por outro lado, sendo a arqueologia portuguesa deficitária em profissionais que se dediquem ao estudo de períodos mais recentes e reforçando-se a tendência da arqueologia de salvamento em detrimento da arqueologia de investigação, é notória a falta de motivação e sobretudo de tempo e meios económicos disponíveis para avançar com estudos desta natureza. Apesar do IPPAR reflectir as dificuldades sentidas em termos nacionais, não podemos esquecer algumas iniciativas importantes bem como, o facto de ter sido graças à diligência das Direcções Regionais deste Instituto que se concretizaram os melhores trabalhos em Arqueologia da Arquitectura portugueses realizados no âmbito de vastos projectos de reabilitação de imóveis afectos. Sendo clara a noção de que a Arqueologia da Arquitectura é o instrumento de análise mais rigoroso quando se trata de registar a biografia de um edifício e que, tal como hoje já existe, no âmbito do IPPAR, a consciência clara que qualquer intervenção ao nível do subsolo deverá implicar sempre um registo arqueológico prévio, torna-se agora necessário criar uma nova rotina que obrigue a que sempre que se programe uma intervenção ao nível do edificado, esta seja sempre precedida de um registo rigoroso, pois de outra forma continuaremos a assistir ao desaparecimento de informações únicas e irrepetíveis e ao nascimento de projectos de reabilitação sem qualquer fundamentação séria.

Triazine herbicide fate in a no-tillage corn ( Zea mays L.)-Crownvetch ( Coronilla varia L.) “Living mulch” system

Chloro- s-triazine herbicide dissipation and leaching potential were examined in two untilled soils planted to corn ( Zea mays L.) in a crownetch ( Coronilla varia L.) “living mulch” sod. Herbicides studied were simazine (6-chloro- N, N′ -diethyl-1,3,5-triazine-2,4-diamine), atrazine (6-chloro- N-ethyl- N′-(1-methylethyl)-1,3,5,-triazine-2,4-diamine, cyanazine (2-[[4-chloro-6-(ethylamino)-1,3,5,-triazin-2- yl]amino]-methylpropanenitrile) and procyazine (2-[[4-chloro-6-(cycloproylamino)-1,3,5,-triazin-2- yl]amino]-2-methylpropanenitrile). Each was applied at 2.2 and 4.5 kg (active ingredient) ha −1. Soil profiles were sampled twice yearly in 15-cm increments to 91 or 122 cm deep. These soil fractions were analyzed for parent herbicide residues. Herbicide dissipation and translocation were rapid and extensive under no-tillage management, and herbicide distribution in the different soil profiles was not predictable solely on the basis of water solubility of the chemicals or soil texture. The probability of detecting subsoil levels of these herbicides was as great in the Murrill silty clay loam as in the Morrison sandy loam. Simazine and atrazine were more persistent and detected more frequently at lower profile depths than cyanazine and procyazine, which are considerably more water soluble. Redistribution of simazine and atrazine by leaching from early to mid-season was also more evident in each soil.

VERMICULITE–PERLITE–CLAY MIXTURES AS CONTAINER GROWTH MEDIA

Vermiculite–perlite–clay (Putnam subsoil) mixtures with added nutrients were evaluated as growth media for periods up to 112 days in 3.8-liter jars using tomato (Lycopersicon esculentum Mill. cv. Patio Hybrid) as a test plant. Although vermiculite–perlite (V–P) ratio had no effect, subsoil levels above 50 g/jar and low N rate (22.5 meq/50 g subsoil) gave greatest growth of 42-day transplants. For long-term periods (112 days), only fruit yield was affected by V–P ratio, a 1:1 (vol/vol) proportion giving the highest yield. Large yield increases were obtained by increasing subsoil to the 150-g or 300-g levels. Fresh and dry plant weights increased with each increment of subsoil, and high N rate (45 meq/50 g subsoil) increased both vegetative growth and fruit yield to levels approaching those obtained with Cornell peat-lite mix A. The V–P clay mixes held more than twice the available moisture present in the peat-lite mix.

Cotton Growth in an Acid Fragipan Subsoil: II. Effects of Soluble Calcium, Magnesium, and Aluminum on Roots and Tops

AbstractGreenhouse and laboratory studies were made to evaluate the effects of soluble Ca, Mg, and Al on cotton (Gossypium hirsutum) growth in highly acid fragipan subsoil (Dickson series). Growth response was not related to soil pH, per se. The high level of soluble Al inherent in the Dickson subsoil greatly inhibited cotton growth by inducing morphological damage to the root system and by depressing uptake of Ca. Yield reductions were accompanied by Al concentrations above 0.2 and 0.02% in roots and tops, respectively. Severe Ca deficiency symptoms in tops and roots were observed where Ca was maintained at inherent subsoil levels and Al was either neutralized with base or was leached from the soil system. Although all treatment yields were not related to Ca or Mg concentrations in plant tissue, results suggested that the native levels of exchangeable Ca and Mg in Dickson fragipan subsoil may be limiting for cotton growth. Whether or not the “inherent” deficiency of Ca is entirely or only partly Al‐induced was not conclusively determined; however, this question may be relatively unimportant in view of the other harmful effects of high levels of soluble Al on cotton growth.

Effect of Carbon Dioxide on Cotton Seedling Root Penetration of Compacted Soil Cores

AbstractThe level of CO2 and of subsoil density were varied in a growth chamber study of the interaction of these two factors on root growth of cotton seedlings at constant O2 concentration. At very low density root elongation rate decreased progressively with increasing CO2, although moderate to good growth occurred even at 24% CO2, the highest concentration used. At higher subsoil level densities, CO2 had little effect on root penetration. Retardation by CO2 was somewhat more severe for roots growing into solution culture than for those growing into loose subsoil, indicating that application of results of aeration experiments in nutrient solution to soils should be made with caution. Results suggest that in well‐drained, medium‐to‐coarse‐textured soils such as the Norfolk, CO2 will seldom be a limiting factor for root growth even in compacted zones near the surface. The mechanical impedance of such zones, will definitely restrict root penetration and proliferation in subsoils.

Mange striber på kryds og tværs

Many criss-cross furrows Viborg Museum has, in the past three years, investigated three tumuli of neolithic date, all covering a network of ard furrows.At Aptrup a tumulus, ploughed down to a maximum height of 75 cms, with a diameter of about 13 meters and apparently no ring stones, covered a plank-coffin burial, the lowest plank of which rested on the subsoil (Fig. 3). The burial contained a battleaxe, while a secondary, stone-framed burial at the west edge of the tumulus and ten cms. above subsoil contained a little cord-ware beaker (Fig. 4).The ard furrows covered an irregular area reaching to within 1.5 meters of the edge of the tumulus. The furrows lay in two directions, E-W and NNW-SSE, the former being clearer, and were about 30 cms. apart and 5-15 cms. broad. The hard clay retained the impress of the U-shaped, sometimes slightly oblique, furrow to a depth of 2-8 cms.The furrows cross the top of -and are therefore later than- a pit containing charcoal dated by C-14 analysis to 2740 ± 100 BC (K 955), while they are earlier than the grave furnishings, which both belong to the transitional period between the bottom-grave and ground-grave subdivisions 1).At Lerchenfeldt a mound, with a diameter of 13.5 meters and preserved to a height of 1.5 meters, contained a trough-shaped stone bedding suggesting a perished oak-coffin burial, secondary urn and cremation burials of Late Bronze Age date, and portions of a ring of quite large edge stones. The mound, of turves, had been laid above the original topsoil, and the net of ard furrows covered the whole area under the mound and the ring-stones, being visible in the subsoil sand and in one area even traceable up through the topsoil (Fig. 4), showing the depth of ploughing to have been at least 20-25 cms. (allowing for compression of the topsoil). Furrows lay in two directions, E-W and NNW-SSE (Fig. 5), the E-W furrows being only half the distance apart of the others, 10-15 cms. against about 30 cms. The width of the actual furrows was 2-15 cms., and in section they were symmetrically semicircular.Two fragments of cord-decorated ware from the furrows give a lower limit for their dating, and the central grave an upper limit.At South Borup a ruined tumulus, about 15 meters in diameter, had had its primary grave removed, but contained peripheral secondary burials, including one ground-grave. In the subsoil sand a small area showed a net of ard furrows, in two directions with an interval of 25 cms. between the furrows, themselves about 5 cms. wide (Fig. 6). Five sherds of neolithic type, one reminiscent of the single-grave and another of the funnel-beaker cultures, were found at subsoil level in and near the furrow area.These three excavations show ploughing taking place in stiff clay, sand and humus/sand. The instrument used could clearly work heavy soil and plough to a depth of 20-25 cms.The presence of furrows below three tumuli associated with the single-grave culture brings into question the traditional belief that the single-grave people had an ecology based entirely upon cattle-raising 5), and that furrows beneath their tumuli should be attributed to earlier inhabitants of the same area 3). This theory can perhaps be tested by experiments to find out how long furrows persist in the subsoil when not covered by a tumulus. The fact that the furrows under the Aptrup tumulus disappear towards the edge of the mound, where the coating of soil is thinnest, suggests that traces of furrows may have a limited "life" under open field conditions.Peter Seeberg and H. H. Kristensen