Cavity spot of carrots - observations on a commercial crop

A single field of commercially-grown carrots was sampled in September at 16 points for cavity spot incidence. Carrot tops, root core and peel were analysed for N, P, K, Ca and Mg, and soils were analysed for organic C, total N, available P, K, Ca, Mg and Na, pH, conductivity and chloride. The incidence of the disorder varied from 0–96% within a small area of field, thus tending to rule out explanations for cavity spot based entirely on weather, genotype etc. Several types of lesion were recorded in addition to ‘typical’ cavity spot, and their incidence was found to be mutually correlated. Most of these (including splitting) were positively correlated with cavity spot, and tended to be positively related to concentrations of macroelements in the carrot peel (especially N and Ca): however, ‘scabs’ were very strikingly dissociated from cavities (both on a plot and individual root basis). This dissociation appeared to be connected with soil pH, in that scabs were most common above pH 6-5, whereas cavities were most frequent below this pH.     

The effect of soil nutrient availability on retranslocation of Ca,Mg and K from senescing sapwood in Atlantic white cedar

Nutrient resorption from senescing tissues increases plant nutrient-use efficiency, and may be an adaptation to nutrient limitation. In some tree species, retranslocation of nutrients from sapwood during heartwood formation is a comparable process. We measured Ca, Mg and K concentrations in Atlantic white cedar (Chamaecyparis thyoides) stemwood samples taken from two swamps in the northeastern United States and compared them to soil mineral nutrient availability at each site. We found that Ca, Mg and K concentrations were 60–700% higher in sapwood than in the immediately adjacent heartwood, indicating retranslocation of these nutrients from senescing sapwood. Sapwood nutrient concentrations were similar between the two sites. However, nutrient concentrations in the heartwood differed significantly between the sites, as did the relative degree of Ca and Mg retranslocation from senescing sapwood. We found these differences between sites to be inversely related to significant differences in exchangeable Ca, Mg and K as well as Al concentrations in the soil. These findings suggest that the degree of nutrient retranslocation from senescing sapwood may be influenced by soil nutrient availability. This revised version was published online in July 2006 with corrections to the Cover Date.     

青藏高原掌叶大黄和丽江大黄及其土壤的主要元素含量

采集掌叶大黄（Ｒｈｅｕｍ ｐａｌｍａｔｕｍ）和丽江大黄（Ｒｈｅｕｍ ｌｉｋｉａｎｇｅｎｓｅ）根茎、叶及根部土壤,应用ＩＣＰ测定主要元素含量特征,研究了２种大黄及其土壤的元素含量特征。结果表明,２种大黄土壤Ｐ含量远低于大黄根茎和叶,Ｆｅ含量则为土壤〉根茎〉叶,其中根茎与叶相差不大,但它们与土壤相差５０～１１０倍;Ｎａ、Ｍｎ、Ｃｕ含量在２种大黄中都表现为土壤〉叶〉根茎,Ｃａ含量在掌叶大黄中为土壤〈叶〈     

Effect of soil K, Ca and Mg saturation and endomycorrhization on growth and nutrient uptake of sugar maple seedlings

Nutrient imbalances of declining sugar maple (Acer saccharum Marsh.) stands in southeastern Quebec have been associated with high exchangeable Mg levels in soils relative to soil K and Ca. A greenhouse experiment was set up to test the hypothesis that the equilibrium between soil exchangeable K, Ca, and Mg ions influences the growth and nutrient status of sugar maple seedlings. Also tested was whether endomycorrhization can alter nutrient acquisition under various soil exchangeable basic cations ratios. Treatments consisted of seven ratios of soil exchangeable K, Ca, and Mg making up a total base saturation of 58%, and a soil inoculation treatment with the endomycorrhizal fungus Glomus versiforme (control and inoculated), in a complete factorial design. Sugar maple seedlings were grown for 3 months in the treated soils. Plant shoot elongation rate, dry biomass and nutrient concentrations in foliage were influenced by the various ratios of soil cations. The predicted plant biomass and foliar K concentration were highest at a soil Ca saturation of 38%, a soil K saturation of 12%, and a soil Mg saturation of 8%. Potassium concentration in foliage was dependent on the level of Ca and Mg saturation in the soil when soil K saturation was close to 12%. Foliar Ca and Mg levels were more dependent on their corresponding levels in soil than foliar K. Colonization by G. versiforme did not influence seedling growth and macronutrient uptake. The results confirm that growth and nutrition of sugar maple are negatively affected by imbalances in exchangeable basic cations in soils.     

Accumulation and subcellular distribution of cations in relation to the growth of potassium-deficient barley

Abstract Growth of barley (Hordeum vulgare L., cv. Georgie) was insensitive to soil K content above about 150 mg kg^?1, but at lower levels it declined. The reduction in yield was greater in soils containing approximately 10 mg Na kg^?1 than in soils with about 90 mg kg^?1 of Na. Growth was unaffected by changes in shoot K concentration above 75 mol m^?3, but declined at lower concentrations, and the decrease was less in plants grown in soils with high Na. Growth responses were not simply related to tissue K concentrations because plants grown in soils with extra Na had higher yields but lower K concentrations. When soil Na was low, plants accumulated Ca as tissue K declined, but when Na was provided this ion was accumulated. Plant Mg concentrations were generally low but increased as K decreased. The Ca and Mg were osmotically active. There were highly significant inverse linear relationships between yield and either the Ca or Mg concentrations in the shoots. X-ray microanalysis was used to examine the compartmentation of cations in leaves from barley plants (cv. Clipper) grown in nutrient solutions with high and low K concentrations. In plants grown with 2.5 mol m^?3 K, this was the major cation in both the cytoplasm and vacuole of mesophyll cells. However, in plants grown with 0.02 mol m^?3 K it declined to undetectable levels in the vacuole, although it was still detectable in the cytoplasm. In all plants, Ca was mainly located in epidermal cells. The implication of the results for explaining responses to K. in terms of compartmentation of solutes is discussed.     

Mineral Elements in Root of Wild Saposhnikovia divaricata and Its Rhizosphere Soil

Mineral elements are important components of medicinal herbs, and their concentrations are affected by many factors. In this study, Ca, Mg, Na, K, Fe, Mn, Cu, and Zn concentrations in wild Saposhnikovia divaricata and its rhizosphere soil collected from seven locations at two different times in China were measured, and influences of rhizosphere soil on those minerals in plant were evaluated. The results showed that mean concentrations of eight minerals in plant samples decreased in the order: Ca > Mg > Na > K > Fe > Zn > Mn > Cu, and those in the soil samples followed the following order: Na > Fe > Ca > K > Mg > Mn > Zn > Cu. Mean concentrations of Ca, Na, Mg, and K in plants were higher than those in soils, while higher mean concentrations of the other four minerals were found in soils. It was found that there was a positive correlation of Mg, Na, and Cu concentrations in the plant with those in the soil respectively, but a negative correlation of Mn concentration in plant with that in the soil. Except Ca, K, and Mn, the other five minerals in plant were all directly affected by one or more chemical compositions of soil. The results also indicate that pH value and concentrations of total nitrogen, Mg, Mn, and Cu in soil had significant correlations with multimineral elements in plant. In a word, mineral elements uptake of S. divaricata can be changed by adjusting the soil fertility levels to meet the need of appropriate quality control of S. divaricata.     

Conservation of element concentration in xylem sap of red spruce

We investigated the chemistry of xylem sap as a marker of red spruce metabolism and soil chemistry at three locations in northern New England. A Scholander pressure chamber was used to extract xylem sap from roots and branches cut from mature trees in early June and September. Root sap contained significantly greater concentrations of K, Ca, Mg, Mn, and Al than branch sap. Sap collected in June contained a signficantly greater concentration of Mn than sap collected in September. Sap concentration was related to forest location for N and Mn. Variations in concentrations of N and K were significantly related to the interaction of tree organ and month of collection. Variations in concentrations of P, Cu, Zn, and Fe were not attributable to tree organ, month of collection, or forest location. Patterns of element concentration in xylem sap compared to previously published data on soil solution chemistry indicated a high degree of homeostatic control of xylem sap chemistry. This control likely represents a significant allocation of resources within the tree energy budget.     

Slash pine seedling response to potassium and calcium on imperfectly drained coastal plain soil

In a greenhouse study, increases in dry weight and N, P, K, Ca, and Mg content of seedlings from a preplanting application of 0.16 meq K/100 g of Caddo silt loam topsoil were markedly greater on soil containing 0.06 meq K, than on soil containing 0.09 meq K/100 g. Except for further increasing K and reducing Ca content of seedlings, applications of 0.32 and 0.48 meq K/100 g added little to growth or nutrient accumulation. Additions of 1 to 5 meq Ca/100 g either did not affect or slightly reduce dry weight and uptake of all nutrients except Ca. Potassium and calcium treatments did not interact to influence growth or nutrient uptake. Dry weight and accumulation of N, P, and K were all associated with the amount of K available; Ca accumulation was related only to available Ca.     

Shoot Sr concentrations in relation to shoot Ca concentrations and to soil properties

This work was aimed to investigate whether shoot Sr concentrations of plant species are related to respective Ca concentrations and to soil properties and to compare the Sr-Ca observed ratios (OR), defined as the quotient of the ratios Sr/Ca in shoots and in the soil solution or in the extractable form, among species and soils. Ten pasture plant species were grown in pots (1-L volume) filled with eight soils differing in the various physicochemical characteristics. Each pot received 50 mg Sr except those of the soil with the highest cation exchange capacity (C.E.C.) that received 100 mg Sr per pot. For each soil, shoot Sr concentrations of species were linearly and positively related with the respective Ca concentrations. C.E.C, organic matter content and Ca in the soil solution or in the extractable form were the only soil properties that were related, all negatively, with shoot Sr concentrations. The ratio of extractable Sr and Ca was positively and linearly related with the ratio of Sr and Ca. in the soil solution. OR was affected by both species and soils. Most of OR values of all species in all soils ranged between 0.8 and 1.5, except for the grass Agrostis capillaris which had the highest values for most of soils. This indicates that Agrostis capillaris compared to other species, takes up proportionally more Sr than Ca.     

Calcium transport mechanisms in dog red blood cells studied from measurements of initial flux rates

Ca2+ efflux from dog red blood cells loaded with Ca2+ using the A23187 ionophore could be separated into two main components: (1) Mg- and ATP-dependent (active transport) and (2) dependent on external Na (K1/2 around 15 mM); at 80 microM internal free Ca the relative magnitudes of these fluxes were 70% and 30% respectively. The Na-dependent Ca2+ efflux had the following additional properties: (i) it was partially inhibited by ATP depletion or preincubation with vanadate, but it was not affected by Mg2+ depletion; (ii) it failed to be stimulated by external monovalent cations other than Na: (iii) it was stimulated by reduction in the internal Na+ concentration. Both active and Na-dependent Ca2+ efflux remained unchanged in hypotonic solutions or in solutions with alkaline pH (8.5). In cells containing ATP and Mg2+, external Ca2+ inhibited Ca2+ efflux (K1/2 around 1 mM); on the other hand, in Mg-free dog red cells external Ca2+ stimulated Ca2+ efflux (K1/2 about 30 microM). In Mg-depleted red cells incubated in the absence of external Na2+, Ca2+ influx as a function of external Ca2+ followed a monotonically saturable function (K1/2 around 20 microM): addition of Na resulted in (i) inhibition of Ca2+ influx and (ii) a sigmoid relationship between flux and external Ca2+. Intracellular Ca2+ stimulated the external Na-dependent Ca2+ efflux along a sigmoid curve (K1/2 around 30 microM); on the other hand the Ca pump had a biphasic response to internal Ca2+: stimulation at low internal Ca2+ (K1/2 between 1 and 10 microM), followed by a decline at internal Ca2+ concentrations higher than 50 microM.     

Effects of inorganic nitrogen application on the dynamics of the soil solution composition in the root zone of maize

The effect of inorganic nitrogen (N) fertilizer on the ionic composition of the soil solution under maize (Zea mays L.) was studied. A pot experiment was carried out with two treatments combined factorially, with or without N application (Ca(NO₃)₂; +N and –N treatments, respectively), and with or without plants. Three looped hollow fiber samplers were installed in each pot to sample soil solutions nondestructively from the root zone, seven times during the 50-day growth period. Plants were harvested on the 50th day, and their nutrient contents determined.Effects of N fertilizer on the soil solutions were observed by the first sampling, 2 days after sowing. The concentrations of Ca and NO₃ ^– and electrical conductivity (EC) increased significantly in the +N treatments as direct effects of fertilizer application. In addition, the concentrations of Mg, K, Na and H⁺ also increased and that of P decreased significantly as indirect effects caused by the re-establishment of chemical equilibria. This suggested the greater supply as well as the greater possibility of leaching loss not only of NO₃ ^– but also of Ca, Mg and K. In the treatments with plants, the concentrations of NO₃ ^–, Ca, Mg and K decreased with time and pH increased significantly compared with the unplanted soil. The depletion of N in the soil solution roughly agreed with the amount of N taken up by the plant. The depletions of K from the soil solution amounted to less than 10% of the amount of the K taken up, suggesting intensive replenishment of K from exchange sites in the soil. Depletions of Ca and Mg were several times higher than the amounts taken up, indicating that the depletions resulted from the adsorption of the divalent cations by the soil rather than uptake by plants. Because NO₃ ^– is hardly absorbed by exchange sites in soil and was the dominant anion in solution, it was concluded that NO₃ ^– had a major role in controlling cation concentrations in the soil solution and, consequently, on their availability for uptake by plants as well as their possible leaching loss. ei]H Marschner     

Bioconcentration of some macrominerals in soil,forage and buffalo hair continuum: A case study on pasture irrigated with sewage water

The present study aimed to evaluate the bioaccumulation of some macrominerals in grazing buffaloes fed forage irrigated with sewage water or canal water. In particular, the transfer of sodium (Na), magnesium (Mg), potassium (K) and calcium (Ca) from soil to plant and in turn to animals was evaluated under sub-tropical environmental conditions. Samples of soil, forage and buffalo hair were collected and digested by wet method. Sodium and K concentrations were significantly higher in the soil but lower in the forages; however, Mg and Ca concentrations in both soil and forages were higher. The correlation between soil, forage and hair showed an imbalanced flow of Na, Mg and K and a balanced flow of Ca from soil to forage and then to animals. Based on the findings, the highest rates of transfer of minerals were found for sewage water treatment, whereas lowest rates were found for canal water treatment, except for Na. As the transfer of minerals depends on their bioavailability, the highest values may be due to the high rates of mineral uptake by plants. Thus, the high transfer rate of some elements by plants could become toxic in future causing detrimental effect to grazing livestock.     

The effects of olive mill waste compost and poultry manure on the availability and plant uptake of nutrients in a highly saline soil

The effects of a compost (produced from by-products of the olive oil industry) and a poultry manure on mineral ion solubility and exchangeability in a highly saline agricultural soil (electrical conductivity for a 1:5 soil:water extract=1.85 dS m(-1)) from Murcia (SE Spain) were studied. The organic amendments did not change significantly the soil electrical conductivity or the soluble Na(+), Ca(2+) or Mg(2+). Only soluble K(+) increased, due to the K(+) supplied by the amendments. The cation exchange capacity increased in treated soils, the exchange complex being mainly saturated with Ca(2+), Mg(2+) and K(+). However, Na(+) was not retained in the exchange sites, and the sodium absorption ratio remained low. The compost and manure increased markedly the shoot growth of the salt-tolerant Beta maritima L. (sea beet) and Beta vulgaris L. (sugar beet). For B. maritima, this seemed to be related to decreases in the shoot concentrations of Na(+) and Cl(-) and increases in K(+) and H(2)PO(4)(-). In the case of B. vulgaris, increases in shoot H(2)PO(4)(-) and B and, for manure-treated soil, a decrease in shoot Na(+) may have been involved. Cultivation of tomato (Lycopersicon esculentum Mill. cv. Moneymaker) in the soil used previously for B. vulgaris indicated that the effects of the manure on tissue cation concentrations were longer-lasting than those of the compost.     

Determinants of Leaf Litter Nutrient Cycling in a Tropical Rain Forest: Soil Fertility Versus Topography

We investigated the influence of landscape-level variation in soil fertility and topographic position on leaf litter nutrient dynamics in a tropical rain forest in Costa Rica. We sampled across the three main edaphic conditions (ultisol slope, ultisol plateau, and inceptisol) to determine the effect of soil nutrients on leaf litter nutrient concentrations while controlling for topography, and to examine topographic effects while controlling for soil nutrients. Both leaf litter macronutrient [phosphorus (P), nitrogen (N), sulfur (S), calcium (Ca), potassium (K), magnesium (Mg)] and micronutrient concentrations were quantified throughout a 4-year period. Leaf litter [P], [N] and [K] varied significantly among soil types. The variation in [P], [N], and [K] was explained by soil fertility alone. Leaf litter [S], [Ca], and [Mg] did not vary among the three soil types. Macronutrient (P, K, Mg, S, Ca) concentrations in the leaf litter were much less variable than those of Fe and Al. Lower variability in essential plant nutrients suggests a great deal of plant control over the amount of nutrients resorbed before senescense. Leaf litter macronutrient concentrations varied significantly over the 4-year period, but the temporal variation did not differ among the three edaphic types as anticipated. Hence, although the magnitude of nutrient fluxes may be controlled by local factors such as soil fertility, temporal patterns are likely regulated by a common environmental variable such as precipitation or temperature.     

Effects of pig manure and wheat straw on growth of mung bean seedlings grown in aluminium toxicity soil

Crop production in red soil areas may be limited by Al toxicity. A possible alternative to ameliorate Al toxicity is the application of such organic manure as crop straw and animal manure. A pot experiment was conducted to investigate the effects of organic materials on the alleviation of Al toxicity in acid red soil. Ground wheat straw, pig manure or CaCO3 were mixed with the soil and incubated, at 85% of water holding capacity and 25 degrees C, for 8 weeks. After the incubation, 14 seedlings of mung bean (Phaseolus aures Roxb) were allowed to grow for 12 days. Results showed that application of organic material or CaCO3 increased soil pH and decreased soil monomeric inorganic Al concentrations. Growth of mung bean seedling was improved sustantially by the application of organic material or CaCO3. Pig manure or wheat straw was more effective in ameliorating Al toxicity than was CaCO3. Mung bean plants receiving pig manure or wheat straw contained relatively high concentrations of P, Ca and K in their leaves. It is suggested that the beneficial effect of organic manure on mung bean is likely due to decreasing concentrations of monomeric inorganic Al concentrations in soil solution and improvement of mineral nutrition.     

The Rengen Grassland Experiment: relationship between soil and biomass chemical properties, amount of elements applied, and their uptake

The Rengen Grassland Experiment (RGE) was established in the Eifel Mountains (Germany) on a low productive Nardetum in 1941. Since then, the following fertilizer treatments have been applied with a late two-cut system: unfertilized control, Ca, CaN, CaNP, CaNPKCl and CaNPK₂SO₄. We aimed to understand how concentrations of macro (N, P, K, Ca and Mg), micro (Cu, Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were affected by long-term fertilizer application, soil chemical properties and biomass production. In 2008, biomass samples from the first cut (early July) and the second cut (mid-October) were collected and analyzed. The simultaneous application of N, P and K decreased nitrogen concentration in the aboveground biomass, but substantially increased biomass production. Late cutting management decreased forage quality in highly productive more than in low productive plant communities. The concentrations of P and K in the plant biomass were positively related to P and K application and, therefore, to plant available P and K concentrations in the soil. The concentrations of some micro (Fe, Mn and Zn) and trace (As, Cd, Cr, Ni and Pb) elements in the plant biomass were negatively correlated with the amount of elements supplied by fertilizers and biomass production, probably because of the dilution effect. Long-term fertilizer application resulted in the accumulation of macro (P, Ca and Mg), micro (Fe and Mn) and trace (As and Cr) elements in the soil, but in many cases this accumulation was not connected with an increase in the concentrations of these elements in the plant biomass. Nutritional status, as indicated by the biomass N:P ratio, was consistent with N or P limitation as indicated by the nitrogen and phosphorus nutrition indices. Furthermore, additional K (co-)limitation was indicated by the N:K and K:P ratios in the biomass from the NP treatment. The results from the RGE indicate that there is no simple positive relationship between the applied elements and their concentrations in the plant biomass.     

Intercropping of Green Garlic (Allium sativum L.) Induces Nutrient Concentration Changes in the Soil and Plants in Continuously Cropped Cucumber (Cucumis sativus L.) in a Plastic Tunnel

A pot-based experiment was conducted to investigate nutrient concentrations in cucumber plants intercropped with various amounts of green garlic. In addition, the soil nutrient contents were studied over two consecutive growing seasons. The results revealed that the accumulation of biomass and the nutritional elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and manganese (Mn) in cucumber plants were significantly increased for intercropping treatments during the two growing seasons compared to monoculture. Conversely, magnesium (Mg) concentrations were decreased in the cucumber plants. Shoot iron (Fe) concentrations decreased whereas root Fe concentrations increased in the intercropping system. Shoot and root zinc (Zn) concentrations decreased during the fall of 2011 but increased during the spring of 2012. Soil organic matter and available N, P and K were significantly increased as the proportion of intercropped green garlic increasing. Medium levels of intercropping green garlic improved cucumber nutrient concentrations the most. The regression analysis showed that the concentrations of most elements were significantly related to the amounts of garlic bulbs, especially the microelements in the spring 2011. The available soil N and organic matter were linearly related to the amounts of garlic bulbs. The results indicate that the nutritional status of the soil and plants of continuously cropped cucumber could be improved by intercropping with green garlic.     

Changes in the extractability of cations (Ca,Mg and K) in the rhizosphere soil of Norway spruce (Picea abies) roots

Nutrient concentrations in the rhizosphere soil can be higher, lower or remain unchanged compared to the bulk soil, but relatively little is known about such changes for basic cations in the rhizosphere of tree roots. A modified root container technique of studying rhizosphere processes was employed. Plexiglas cylinders were horizontally split by a membrane with 30 M mesh size into an upper compartment for root growth and a root-free lower compartment, each with an inner diameter of 5 cm and a height of 10 cm. One 2-year-old Norway spruce (Picea abies) seedling was transplanted from a nursery into each cylinder. Plants were not specifically inoculated, but roots were colonised by a mix of ectomycorrhizal fungi originating from the nursery. The nutrient poor mineral soil used in the experiment was taken from a forest site in Bayerischer Wald, southern Germany. The soil was either supplied with a mix of Ca, Mg and K, or not supplied with these cations. Plants were harvested 30 weeks after transplanting. The nylon membrane between the root compartments restricted root growth to the upper compartment, so that by the end of the experiment a root mat was formed at the top side of the membrane. In the lower compartment, soil nearest to the root mat was regarded as rhizosphere soil while soil in a distance from the root mat was regarded as bulk soil. In the upper compartment, rhizosphere soil was obtained at the end of the experiment by gently shaking the roots. The soils were analysed for Ca, Mg and K contents following two different soil extraction methods. In the fertilised treatment, H₂O-extractable Ca and Mg were accumulated in the rhizosphere. In contrast, K (NH₄Cl-extraction) was depleted in the rhizosphere. In the bottom tube, the depletion of K (NH₄Cl-extraction) was restricted to 1 cm distance from the root mat. In unfertilised soil, Ca, Mg and K concentrations did not differ clearly between rhizosphere and bulk soils. The results indicated that the occurrence of cation gradients in the rhizosphere depended on the level of soil nutrient supply. Distinct rhizosphere effects were measured by conventional soil extraction methods only when the soil was freshly fertilised with mineral elements prior to the experiment. In this case, K depletion in the rhizosphere reflected higher K uptake by the fertilised Norway spruce plants. For low-nutrient soils, novel techniques are required to follow subtle changes in the rhizosphere.     

The influence of lead,cadmium, and nickel on the growth of ryegrass and oats

Summary A 2⁴ factorial experiment was conducted under greenhouse conditions. Factors and levels in the experiment were soil pH at 4.5 and 6.4, and cadmium, lead, and nickel added to the soil to provide soil concentrations of 50, 250, and 50 ppm, respectively, above background levels. Two species were grown in succession in the same experimental pots. Ryegrass (Lolium hybridum Hausskn. cv. Tetrelite) was harvested three times and then one crop of oats (Avena sativa L. cv. Garry) was grown and harvested. Plant tissue concentrations of cadmium, lead, and nickel were monitored throughout the experiment.Addition of cadmium to the soil lowered the dry matter yields in all three ryegrass harvests and also reduced the yield of oat grain. The application of lead nitrate to the soil enhanced the yield of ryegrass obtained at the first harvest and also increased the yield of oat grain. Nickel, added to the soil at 50 ppm, was relatively innocuous to ryegrass and oats.The presence of added cadmium, lead, or nickel to the soil resulted in enhanced tissue concentrations of these metals in both ryegrass and oats. This effect was particularly enhanced by a soil pH of 4.5. A single exception to this observation was that lead was not detected, under any of the conditions of this experiment, in oat grain.The presence of lead in the soil enhanced cadmium concentrations in ryegrass tissues. The presence of cadmium in the soil decreased lead tissue concentrations in ryegrass and oat straw. Soil pH interacted with both nickel and lead in the second ryegrass harvest with subsequent changes in tissue cadmium concentrations. At a soil pH of 4.5, the presence of added lead or nickel to the soil significantly increased the ryegrass tissue cadmium concentration beyond that observed at a soil pH of 6.4 with or without enhanced nickel or lead concentrations.     

Factors affecting tissue nutrient concentrations in aCarex meadow

Summary The influence of community and edaphic variables on tissue nutrient concentration was assessed for seven species on aCarex wetland in southern Quebec, Canada.Potassium and sodium tissue levels were considerably higher and Ca and Mg 35% lower than in a deciduous forest. Macronutrient concentrations decreased in the order K>N>Ca>Mg>Na>P. Micronutrient concentrations (Fe>Mn>Zn>Cu) ranged from 0.038–0.005 mg/g. This was 2–3 times less abundant than in an adjacentScirpus wetland. Inter-species coefficient of variation in N, P and K was low (14%) compared to variation in Ca, Mg, and the micronutrients (35%).Principal components analysis of interrelations between tissue elements indicated a clear distinction between N, P, K, Cu, Mn, and Zn levels and ash, Ca, Mg, Na, and Fe levels on the first component. This difference related closely to water depth and fire incidence. The coincidence of burning with water depth and the period of maximum snowmelt and runoff in the Spring suggested the loss of N, P, K, Cu, Mn and Zn by volotilization, runoff, or leaching.Stem density was the most important parameter influencing tissue N, P, and K concentrations whereas soil nitrogen levels were important in ash, Ca, and Mg concentrations. Water depth was the most important variable in the case of Cu, Fe, Mn, Na and Zn levels. Typha angustifolia had the highest level of total nutrients in green tissue,Carex lanuginosa the lowest. Principal components analysis indicated soil nitrogen, water depth, and soil potassium levels, in that order, were the three most important variables influencing the patterns of tissue element variation among species.Potassium and sodium levels in 1-year old litter were 11% and 0.4% compared to concentrations in green tissue. Iron and manganese, both subject to oxidation and adsorption to litter at the soil surface, were distinctly higher (2247% and 199%) in litter than green tissue. Concentrations of these and other elements in litter were consistent with results reported in literature and indicated litter was especially active as a site of cation exchange in the system.