Home About us Contact
|
Home About us Contact | ||
|
|
||
Kg Soil (kg + soil)
Selected AbstractsBioavailability and microbial adaptation to elevated levels of uranium in an acid, organic topsoil forming on an old mine spoilENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2007Erik Jautris Joner Abstract An old mine spoil at a 19th-century mining site with considerable residues of uranium (400,800 mg U/kg) was investigated with respect to U concentrations in soil and plants and tolerance to U in the soil microbial community in order to describe the bioavailability of U. Measurements of soil fractions representing water-soluble U, easily exchangeable U, and U bound to humified organic matter showed that all fractions contained elevated concentrations of U. Plant U concentrations were only 10 times higher at the mine spoil site compared to the reference site (3 mg U/kg vs 0.3 mg U/kg), while the most easily available soil fractions contained 0.18 to 0.86 mg U/kg soil at the mine spoil. An ecotoxicity bioassay using incorporation of [3H]thymidine into the indigenous microbial communities of the two soils in the presence of increasing U concentrations showed that microorganisms at the mining site were sensitive to U but also that they had acquired a substantial tolerance toward U (EC50, the effective concentration reducing activity by 50% of UO2 -citrate was , 120 ,M as compared to 30 ,M in the reference soil). In the assay, more than 40% of the microbial activity was maintained in the presence of 1 ,M UO2-citrate versus 3% in the reference soil. We conclude that U-enriched mining waste can contain sufficiently elevated concentrations of bioavailable U to affect indigenous microorganisms and that bioavailable U imposes a selection pressure that favors the development of a highly uranium-tolerant microbial community, while plant uptake of U remains low. [source] Estimation of the phosphorus sorption capacity of acidic soils in IrelandEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2001R. O. Maguire Summary The test for the degree of phosphorus (P) saturation (DPS) of soils is used in northwest Europe to estimate the potential of P loss from soil to water. It expresses the historic sorption of P by soil as a percentage of the soil's P sorption capacity (PSC), which is taken to be , (Alox + Feox), where Alox and Feox are the amounts of aluminium and iron extracted by a single extraction of oxalate. All quantities are measured as mmol kg soil,1, and a value of 0.5 is commonly used for the scaling factor , in this equation. Historic or previously sorbed P is taken to be the quantity of P extracted by oxalate (Pox) so that DPS = Pox/PSC. The relation between PSC and Alox, Feox and Pox was determined for 37 soil samples from Northern Ireland with relatively large clay and organic matter contents. Sorption of P, measured over 252 days, was strongly correlated with the amounts of Alox and Feox extracted, but there was also a negative correlation with Pox. When PSC was calculated as the sum of the measured sorption after 252 days and Pox, the multiple regression of PSC on Alox and Feox gave the equation PSC = 36.6 + 0.61 Alox+,0.31 Feox with a coefficient of determination (R2) of 0.92. The regression intercept of 36.6 was significantly greater than zero. The 95% confidence limits for the regression coefficients of Alox and Feox did not overlap, indicating a significantly larger regression coefficient of P sorption on Alox than on Feox. When loss on ignition was employed as an additional variable in the multiple regression of PSC on Alox and Feox, it was positively correlated with PSC. Although the regression coefficient for loss on ignition was statistically significant (P <,0.001), the impact of this variable was small as its inclusion in the multiple regression increased R2 by only 0.028. Values of P sorption measured over 252 days were on average 2.75 (range 2.0,3.8) times greater than an overnight index of P sorption. Measures of DPS were less well correlated with water-soluble P than either the Olsen or Morgan tests for P in soil. [source] Effects of Interactions of Moisture Regime and Nutrient Addition on Nodulation and Carbon Partitioning in Two Cultivars of Bean (Phaseolus vulgaris L.)JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2001T. Boutraa Major limitations of bean (Phaseolus vulgaris L.) production in arid and semiarid regions are lack of moisture and low soil fertility. An experiment was conducted to determine the effects of soil moisture and N : P : K (20 : 10 : 10) fertilizer on root and shoot growth of two cultivars of bean: cv. Carioca, an indeterminate Brazilian landrace, and cv. Prince, a determinate cultivar grown in Europe. Carioca appears generally stress-tolerant while Prince is intolerant. Seedlings were grown in pots of non-sterile soil at 30, 60 or 90 % field capacity (FC), and given 0, 0.1 or 1 g (kg soil),1 of compound fertilizer. The soil contained a population of effective Rhizobium. Growth of both cultivars was greatest in the high moisture and high nutrient treatments. Root fractions were highest at low nutrient supply; the effect of water was not significant. Leaf fraction decreased as root fraction increased. Numbers of nodules were highest at high and intermediate moisture when no fertilizer was applied. Numbers were lowest at 30 % FC and at the highest fertilizer rate. Masses of nodules and fractions followed the same pattern. Decreasing water regime reduced the relative growth rate (RGR) of Prince, while Carioca maintained high RGR at unfavourable conditions of water and nutrients. Net assimilation rates (NAR) were unaffected by nutrient addition, and reduced by low moisture regime. Water use efficiencies (WUEs) were reduced by water stress but increased by nutrient deficiency. The water utilization for dry matter production was optimal at 60 % FC. Einflüsse der Interaktionen von Bodendenfeuchte und Düngung auf die Knöllchenbildung und Kohlenstoff verteilung bei zwei Bohnenkultivaren (Phaseolus vulgaris L.) Der begrenzende Hauptfaktor der Bohnenproduktion in ariden und semiariden Regionen sind der Feuchtigkeitsmangel und die Bodenfruchbarkeit. Es wurde ein Experiment durchgeführt, um die Wirkungen des Bodenwassers und von N : P : K (20 : 10 : 10) Dünger auf das Wurzel- und Sproßwachstum an zwei Kultivaren von Bohnen (Phaseolus vulgaris L. cv. Carioca, eine brasilianischen, indeterminierte Landsorte und cv. Prince, eine determinierter in Europa angebauter Kultivar) zu untersuchen. Carioca erscheint grundsätzlich streßtoleranter im Vergleich zu Prince. Die Sämlinge wurden in Gefäßen mit nichtsterilisiertem Boden unter Feldkapazitäten von 30,60 oder 90 % mit 0, 0,1 oder 1 g eines Volldüngers angezogen. Der Boden enthielt eine Population von wirksamem Rhizobium. Das stärkste Wachstum wurde bei beiden Kultivaren unter dem Einfluß des höchsten Feuchtigkeitsgehaltes und der höchsten Düngermenge gefunden. Der Wurzelanteil war bei der geringen Düngermenge am niedrigsten. Der Einfluß der Bodenfeuchtigkeit war nicht signifikant. Der Blattanteil nahm mit zunehmendem Wurzelanteil ab. Die Anzahl der Knötchen war bei hoher und mittlerer Bodenfeuchte und ohne Düngeranwendung am höchsten. Die Anzahl war am geringsten bei 30 % FC und der höchsten Düngermenge. Die Knötchenmasse und ihr Anteil reagierte entsprechend. Abnehmende Bodenfeuchte reduzierte die relative Wachtumsrate (RGR) von Prince, während Carioca einen hohen RGR auch bei ungünstigen Bedingungen bezüglich Wasser und Düngung behielt. Die Nettoassimilationsraten wurden durch die Düngung nicht beeinflußt; sie gingen bei geringer Bodenfeuchte zurück. Die Wassernutzungseffiziens (WUE) wurde bei Wasserstreß reduziert, nahm aber bei Düngermangel zu. Die Wassernutzung für die Trockenmasseproduktion war bei 60 % Feldkapazität am höchsten. [source] Nitrogen effects on total flavonoids, chlorogenic acid, and antioxidant activity of the medicinal plant Chrysanthemum morifoliumJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2010Dahui Liu Abstract Chrysanthemum morifolium (Ramat.) has a long history of cultivation and use as a traditional medicine and tea plant in China. A greenhouse experiment with potted soil,quarz mixture studied the effects of nitrogen supply (0, 56, 112, 167, 224, 334, 501, 556, and 668 mg N,kg,1) on concentrations and ratios of total flavonoids and chlorogenic acid in the flowers of C. morifolium using spectrophotometric and HPLC methods. The antioxidant activity of the flowers was determined as the radical scavenging activities of hydroxyl, superoxide anion, and 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radicals. A high N supply decreased the concentrations of total flavonoids by 18%,35% and that of chlorogenic acid by 8%,60% compared to a low N-supply rate. At the same time, increasing N supply significantly decreased the antioxidant activity of the flowers. The antioxidant activity of C. morifolium flowers was significantly positively correlated with the concentrations of total flavonoids and chlorogenic acid. We conclude that an N supply in excess of 300 mg (kg soil),1 will negatively affect the antioxidant activity and thereby reduce the quality of C. morifolium flowers. [source] Arsenic accumulation by rice grown in soil treated with roxarsoneJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2009Chen-Wuing Liu Abstract Poultry litter is widely used as a fertilizer for lowland rice in Taiwan and China. However, the organic-arsenic compound roxarsone (additive of poultry feed) in poultry litter can be absorbed by the plants and the resulting arsenic (As) contamination may pose a serious threat to human health. This study used various amounts of poultry litter contaminated with roxarsone in pot experiments to evaluate the effect of roxarsone on rice agronomic parameters and the bioaccumulation of total and inorganic As in rice-plant tissues. Rice-grain yield decreased significantly with increasing As content of the soil, and the critical threshold that killed rice was 200 mg roxarsone (kg soil),1. The As concentrations in root, straw, leaf, husk, and grain increased with increasing soil As (p < 1%). At 100 mg roxarsone per,kg of soil, the As concentration in the rice grain exceeded the statutory permissible limit of 1.0 mg As (kg dry weight),1 and at 25 mg roxarsone (kg soil),1, the inorganic As concentrations in grains exceeded the statutory limit of 0.15 mg of inorganic As,kg,1 in China. For all treatments, the As concentrations in various plant tissues at maturity follow the order: root > stem > leaf > husk > grain. Arsenite was the predominant species in root, straw, and grain, while arsenate was the predominant species in leaf and husk. No significant difference existed between the amounts of arsenite and arsenate when various amounts of poultry litter were applied. This result illustrates that large amounts of added roxarsone are not only toxic to rice but also accumulate in grains in the inorganic As forms, potentially posing a threat to human health via the food chain. [source] Uptake of residual phosphate and freshly applied diammonium phosphate by Lolium perenne and Trifolium repens,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2003Anne Gallet Abstract Residual fertilizer phosphorus (residual P) may significantly contribute to crop P nutrition. To test this hypothesis, a pot experiment was conducted with ryegrass (Lolium perenne) and clover (Trifolium repens) grown separately on three different soils which either had not received P fertilizer for at least nine years (0F) or had received P fertilizer equivalent to crop P off-take (F). Soils in the pot experiment were given either none (0F, F) or a single rate of 15 mg P (kg soil),1 as diammonium phosphate (0F+DAP, F+DAP). In the treatments 0F+DAP and F+DAP DAP had been labeled with 33PO4 while in the treatments 0F and F the pool of available soil P had been labeled with carrier-free 33PO4. This allowed estimating the quantities of P in plant dry matter that derived from native soil P, residual fertilizer P or fresh fertilizer P. Fourteen to 62,% of the P in the above ground biomass of white clover or perennial ryegrass were derived from residual P whereas 7 to 28,% were derived from freshly applied DAP. The proportion of P derived from residual P was correlated to the total amount of P fertilizer added to the soils, while the proportion of P derived from DAP was correlated to the concentration of P in the soil solution of the 0F and F soils. Aufnahme von Phosphat aus Rückständen von früherer Düngung und aus frisch ausgebrachtem Diammoniumphosphat durch Lolium perenneund Trifolium repens In Düngerrückständen enthaltener Phosphor (P) kann möglicherweise signifikant zur P-Ernährung von Kulturpflanzen beitragen. Um diese Hypothese zu prüfen, wurde im Topfversuch die P-Aufnahme durch Lolium perenne und Trifolium repens untersucht. Als Substrat dienten drei Böden, die entweder seit mindestens 1989 keine P-Gabe mehr erhalten hatten (0F) oder die jährlich P-Gaben im Umfang der P-Entzüge durch die vorgängigen Kulturen erhalten hatten und deshalb P-Rückstände enthielten (F). Es ergaben sich folgende Verfahren: 0F: ohne P aus Düngerrückständen und frischer Düngung; 0F+DAP: mit P aus frischer Düngung (Diammoniumphosphat, 15 mg P (kg Boden),1); F: mit P aus Düngerrückständen; F+DAP: mit P aus Düngerrückständen und frischer Düngung. In den Verfahren 0F + DAP und F + DAP war DAP mit 33PO4 markiert. In den Verfahren 0F und F war der verfügbare P des Bodens mit carrier-freiem 33PO4 markiert. Dies ermöglichte die Erfassung der Aufnahme von P durch die Pflanzen differenziert nach Herkunft aus Boden, Düngerrückständen und frischem Dünger. Von Düngerrückständen stammten 14,62,%, von frischem Dünger 7,28,% des in den Sprossen der Pflanzen gefundenen P. Der von Düngerrückständen stammende Anteil P in den Pflanzensprossen war korreliert mit dem gesamten Gehalt an P das dem Boden als Dünger zugeführt worden war. Der von frischem DAP stammende Anteil war korreliert mit der P-Konzentration in der Bodenlösung. [source] Effect of phosphate fertilization on crop yield and soil phosphorus status,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2003Anne Gallet Abstract To evaluate the effect of three phosphorus (P) fertilization regimes (no P, P input equivalent to P off-take by crops, P input higher than P off-take) on crop yield, P uptake, and soil P availability, seven field experiments (six in crop rotations, one under permanent grassland) were conducted in Switzerland during nine years (six trials) or 27 years (one trial). Soil total P (Pt), inorganic P (Pi), organic P (Po), and the amount of isotopically exchangeable soil P were measured in the 0,20,cm and 30,50,cm layers of the arable soils and in the 0,10,cm layer of the permanent grassland soil. Omitting P fertilization resulted in significant yield decreases only in one field crop trial as the amount of P isotopically exchangeable within one minute (E1min) reached values lower than 5 mg P (kg soil),1. In the absence of P fertilization Pi decreased on average from 470 to 410 mg P (kg soil),1 in the upper horizon of 6 sites while Po decreased only at two sites (from 510 to 466 mg P (kg soil),1 on average). In all the treatments of the trials started in 1989 the E1min values of the upper horizon decreased on average from 15.6 to 7.4 mg P (kg soil),1 between 1989 and 1998. These decreases were also observed when P inputs were higher than crops needs, showing that in these soils the highest P inputs were not sufficient to maintain the high initial available P levels. Finally for the six arable trials the values of the isotopic exchange kinetics parameters (R/r1, n, CP) and P exchangeable within 1 minute (E1min) at the end of the experiment could be estimated from the values measured at the beginning of trial and the cumulated P balance. Der Einfluss der Phosphordüngung auf den Pflanzenertrag und den Phosphorstatus des Bodens Die Begrenzung der Düngung mit Phosphat (P) bei Böden, die bereits hohe Gehalte an verfügbarem P aufweisen, kann zur Verringerung der P-Verluste in Oberflächen- und Grundwasser beitragen. Sieben Feldversuche (6 Versuche mit Ackerkulturen, 1 Versuch mit Dauerwiese) wurden während 9 Jahren (6 Versuche) resp. 27 Jahren (1 Versuch) durchgeführt mit dem Ziel, den Einfluss von drei Düngungsraten (keine P-Gabe, P-Gabe entsprechend dem P-Entzug durch die Pflanzen und P-Gabe höher als der P-Entzug durch die Pflanzen) auf Pflanzenertrag, P-Aufnahme und P-Verfügbarkeit zu studieren. Die Gehalte an anorganischem P (Pi) und organischem P (Po), sowie deren Summe (Pt) und die Gehalte an isotopisch austauschbarem P wurden in den Bodentiefen von 0,20,cm und 30,50,cm der ackerbaulichen Versuche und in einer Bodentiefe von 0,10,cm in der Dauerwiese gemessen. Der Verzicht auf P-Düngung führte nur in einem der ackerbaulichen Versuche zu einer signifikanten Abnahme des Pflanzenertrags, wobei der Gehalt an isotopisch austauschbarem P (E1min) unter 5 mg P (kg Boden),1 fiel. Pi sank bei Verzicht auf P-Düngung im oberen Horizont von 6 Böden durchschnittlich von 470 auf 410 mg P (kg Boden),1, während Po nur in 2 Böden absank (durchschnittlich von 510 auf 466 mg P (kg Boden),1). Ueber alle Düngungsverfahren jener Versuche, die 1989 begonnen hatten, sank E1min im oberen Horizont von 1989 bis 1998 durchschnittlich von 15.6 auf 7.4 mg P (kg Boden),1. Die Abnahme wurde auch beobachtet, wenn die P-Gabe höher war als der P-Entzug durch die Pflanzen, was zeigt, dass in diesen Böden selbst die höchste P-Gabe nicht genügte, um den ursprünglich hohen Gehalt an verfügbarem P aufrecht zu erhalten. Schließlich wurden in den 6 ackerbaulichen Versuchen die Parameter der Isotopenaustauschkinetik (R/r1, n, CP) und E1min am Ende des Versuches mit den ursprünglichen Werten zu Beginn des Versuchs verglichen. Es ergaben sich signifikante Beziehungen zwischen den Werten am Ende des Versuchs einerseits und den ursprünglichen Werten und der P-Bilanz andererseits. [source] | ||||||||||