Availability Of Trace Elements Research Articles

Improved Thermal Stability of a Novel Acidophilic Phytase.

Phytase increases the availability of phosphate and trace elements by hydrolyzing the phospho-monoester bond in phytate present in animal feed. It is also an important enzyme from an environmental perspective because it not only promotes the growth of livestocks but also prevents phosphorus contamination released into the environment. Here we present a novel phytase derived from Turicimonas muris, TmPhy, which has distinctive structure and properties compared to other previously known phytases. TmPhy gene expressed in the Pichia system was confirmed to be 41 kDa in size and was used in purified form to evaluate optimal conditions for maximum activity. TmPhy has a dual optimum pH at pH3 and pH6.8 and exhibited the highest activity at 70℃. However, the heat tolerance of the wildtype was not satisfactory for feed application. Therefore, random mutation, disulfide bond introduction, and N-terminal mutation were performed to improve the thermostability of the TmPhy. Random mutation resulted in TmPhyM with about 45% improvement in stability at 60℃. Through further improvements, a total of three mutants were screened and their heat tolerance was evaluated. As a result, we obtained TmPhyMD1 with 46.5% residual activity, TmPhyMD2 with 74.1%, and TmPhyMD3 with 66.8% at 80℃ heat treatment without significant loss of or with increased activity.

Using cattle hair to assess exposure to essential trace elements in volcanic soils

BackgroundIn areas where cattle graze outdoors, the environmental availability of trace elements is of utmost importance for an adequate intake. Cattle hair trace elements can be used as exposure biomarkers to assess animal intake and help ensure good nutrition and animal welfare. The aim of this study was to evaluate the environmental exposure to trace elements in cattle grazing outdoors in a volcanic region (São Miguel Island, Azores) and assess the corresponding bioaccumulation factors. MethodsTwenty-nine samples of pasture topsoil were collected in two areas of São Miguel with different geological characteristics: Picos fissure system (basaltic area) and Povoação volcano (trachytic area). Hair from fifty-four animals (calves and dairy cows) was collected in two grazing sites: Ponta Delgada (Picos fissure system) and Povoação (Povoação volcano). All samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS) after digestion in aqua regia. ResultsBasaltic soils of the Picos fissure system had significantly higher concentrations of most trace elements, except Mo, when compared with the trachytic soils of Povoação volcano. Hair of calves from Povoação showed higher concentrations of most essential trace elements, except Mg, Cu, and Zn, than hair from calves of Ponta Delgada (considered in this study as a control group since they are raised in a barn). On the other hand, hair from dairy cows grazing in Ponta Delgada showed higher concentrations of most essential trace elements, except Mg, As, and Mo, when compared with hair of cows grazing in Povoação. ConclusionsCattle hair trace elements are suitable biomarkers for the assessment of the environmental exposure to trace elements in volcanic soils. The results from dairy cows support the uneven distribution of essential trace elements (and their bioavailability) in the different soils of São Miguel, reinforcing the need to graze animals outdoors from an early age. Such practice (grazing cattle outdoors) provides another means of accessing essential trace elements that complemented with feed can reduce the natural depletion of these essential elements in the body due to reproductive phenomena and milk production.

Effects of thermal hydrolysis process-generated melanoidins on partial nitritation/anammox in full-scale installations treating waste activated sludge

Thermal hydrolysis process (THP) is a well-established anaerobic digestion (AD) pre-treatment technology. Despite the THP benefits the pre-treatment increases the concentrations of nutrients and melanoidins in the digestate reject water after dewatering. The increased concentrations of nutrients and melanoidins formed during THP-AD can impact downstream processes, such as struvite precipitation and partial nitritation/anammox (PN/A). In our present work, six full-scale PN/A influents and effluents were sampled in The Netherlands (4 with THP and 2 without THP). Full-scale samples were characterised and the stoichiometric O2 consumption and melanoidins chelated to trace elements were analysed. The results showed that THP increased the concentration of total ammoniacal nitrogen (TAN), chemical oxygen demand (COD), total organic carbon (TOC), UVA 254 and colour, which are indicators of melanoidins occurrence. THP furthermore decreased the stoichiometric NO3−-N production from the PN/A reaction in effluents. The disparity between stoichiometric and measured NO3− -N in the THP-using plants was explained by the proliferation of denitrifiers. Moreover, denitrification improved the N removal efficiency due to the consumption of the stoichiometrically-produced NO3− -N. Also, the stoichiometric O2 consumption increased in the plants using THP, reaching up to 56% of the O2 used for partial oxidation of TAN. Trace elements analysis revealed that the plants with elevated concentrations of melanoidins in the effluent showed a high percentage of chelated multivalent cations, particularly transition metals such as Fe. Kendall correlation coefficient analysis showed that the chelation of multivalent cations was correlated mainly with colour occurrence in the reject waters. Overall, the results indicated that in PN/A systems using THP-AD increased O2 consumption and trace elements availability should be considered during the process design.

The effect of particle size on oral bioavailability and bioaccessibility of soil Ni from different sources

The goal of the work was to contribute to a unified approach to assessing the risk to human health of soil ingestion, for contaminated sites with elevated [Ni]. Robust relationships between in vitro bioaccessibility and in vivo bioavailability of Ni in various soils, with mechanistic understanding, would enable site-specific assessments of human exposure through soil ingestion. Four soils (three ultramafic Brunisols with geogenic Ni and one Organic soil with anthropogenic Ni) were sieved into PS < 10 μm, 10–41 μm, 41–70 μm, 70–105 μm, 105–150 μm, and 150–250 μm, the [Ni]T for which ranged from 560 to 103000 mg/kg. Mass fraction-adjusted [Ni]IVBA (SBRC gastric) for each soil fraction was similar whether calculated for all particles <250 μm or <150 μm %NiIVBA ranged from 3% to 16% of [Ni]T and %NiABA (accumulated Ni in urine, kidneys, and small intestine of Sprague Dawley rats gavaged with a soil) ranged from 0% to 0.49%. The correlation between these two measurements was weak (R2 = 0.06). Multiple linear dose response relationships attributing variation in %NiABA to %NiIVBA plus soil physicochemical parameters known to influence trace element availability in soils were developed. As many soil properties measured in this study were highly correlated, ridge regression enabled a predictive relationship where the effect of each parameter was its true contribution to variation in %NiABA. Using a ridge constant (k) of 0.012, %NiABA could be predicted from %NiIVBA adjusted for soil absorptive entities (OrgC, and Fe oxides (negative coefficients)) and soil pH (positive coefficient). %NiABA predicted from this relationship was very close to 1:1 with the observed %NiABA except at the lowest observed values which were lower than predicted. This study shows that as the conditions increasingly favour soil Ni solubility, more of the Ni was bioavailable; this generalization was true regardless of particle size or soil origin.

Insect Frass as a Novel Organic Soil Fertilizer for the Cultivation of Spinach (Spinacia oleracea): Effects on Soil Properties, Plant Physiological Parameters, and Nutrient Status

Soils naturally low in organic matter need to be amended with recycled organic materials that would boost soil health. In this work, we tested insect frass, the excrements of the yellow mealworm, Tenebrio molitor, as a novel organic soil amendment in a spinach cultivation. In a 60-day pot experiment with spinach (Spinacia oleracea), we added frass at rates of 0, 0.25, 0.5, and 1%, as well as an inorganic nitrogen-phosphorus-potassium (NPK) fertilizer as a positive control. We found that organic matter increased significantly from 2.7% in the unamended control to 3.2% in the treatment of 1% frass, showing that frass has a valuable role in boosting soil carbon (C). Also with increasing frass rates, N uptake by plant was enhanced, due to the fact that nitrogen use efficiency (NUE) remained unchanged. These findings exhibit the fact that added N was utilized satisfactorily. However, frass effectiveness was not successful in the case of added P and K: the likely reason is the already very high P and K available contents in the unamended soil. Spinach growth was significantly favored by the amendment of frass in a rate-dependent manner: the higher biomass accumulation was found under 1% frass—six-fold higher than NC, while even at 0.25% the yield was significantly higher. Plants at this treatment had the highest chlorophyll a + b content throughout the course of the experiment and also exhibited the highest photosynthetic efficiency and performance of the plant photosynthetic apparatus under frass treatments. The index of total photosynthetic efficiency (PItotal) also fared better in the frass-added treatments upwards from 0.25%. We conclude that frass is a highly valuable soil conditioner, given the amble organic C and N that adds to soil, resulting in boosted growth of spinach. As this report is a preliminary study, we suggest that future works should expand frass testing to (a) more plants, where a series of important plant physiology features must be evaluated, and (b) the role of frass in trace element availability.

Availability and transfer of non-essential elements in a rehabilitated bauxite residue grassland system

AimsThis study investigated a 7 yr old rehabilitated grassland established on a bauxite residue storage areas(RSA) in order to assess the availability and ecosystem transfer of both nutrient and trace elements, and to determine if defined rehabilitation criteria were sustained.MethodsRehabilitated residue/soil was sampled over depth (0–10 and 10-20 cm) and season (Spring/Summer and Autumn/Winter) and plant growth stage (green vs. senescent) to determine both essential and non-essential element (Ca, Mg, Na, Al and V) content. Invertebrates samples from both decomposer and predator specimens were assessed to determine if foodchain transfer occurred.ResultsResidue-soil results showed sustained rehabilitation with pH, EC and ESP all within recommended criteria levels. Further, bioavailable fractions of Al and V remained low. Vegetation analysis revealed seasonal variation for both essential and non-essential elements and highlights the need for wider monitoring parameters. Elemental content in invertebrate samples did not indicate foodchain transfer and results were comparable to a reference site.ConclusionResults show sustained rehabilitation with low bioavailability of non-essential elements and foodchain transfer.

Dynamics of the Content and Distribution of Trace Elements in Sod-Podzolic Soils and Plants of Agrocenoses

The paper presents the results of a survey of sod-podzolic soils for agricultural purposes and plants of reference sites of the Ivanovo region for the content of boron, copper, cobalt, manganese and zinc in them, conducted in 2014 and 2021. Correlation analysis determined the influence of individual physical and chemical properties of soils on the content and distribution of available forms of trace elements in the soil and the relationship between the trace elements themselves. Changes in the availability of trace elements of the soils of the plots have been established. According to the amount of content of available forms of trace elements in soils, the need for the use of micronutrients is determined. The sequences of crops were determined by the content of trace elements in grain and straw of cereals, the green mass of forage grasses, as well as the distribution of trace elements between parts of the grown crop. Grain, straw and green mass were evaluated for compliance with veterinary standards for the content of copper, zinc and cobalt in feed. The coefficients of accumulation of trace elements by plant products of crops are calculated and their comparative analysis is carried out. By the magnitude and sign of the correlation coefficients between the concentrations of trace elements in plants, the manifestation of antagonism and synergy between trace elements was determined. The Pearson and Spearman correlation coefficients between the content of mobile forms of trace elements in the soil and their content in plant products, as well as between the content of trace elements in grain and straw of cereals revealed their strength and the ambiguous nature of the relationships..

Soil amendment and rhizobacterial inoculation improved Cu phytostabilization, plant growth and microbial activity in a bench-scale experiment.

Mine driven trace elements' pollution entails environmental risks and causes soil infertility. In the last decades, in situ techniques such as phytostabilization have become increasingly important as ways to tackle these negative impacts. The aim of this study was to test the individual and combined effects of different aided phytostabilization techniques using substrate from barren tailings of a Cu mine, characterized by extreme infertility (high acidity and deficiency of organic matter and nutrients). The experiment analyzed the growth of Populus nigra L. planted alone (P) or in co-cropping with Trifolium repens L. (PT), in pots containing mine soil amended with compost (1, 10, compost, soil, w/w) non inoculated (NI) or inoculated with plant growth promoting rhizobacteria (PGP), mycorrhizae (MYC) or a combination of bacterial and fungal inocula (PGPMYC). Non-amended, non-planted and non-inoculated reference ports were also prepared. Plants were harvested after 110 days of plant development and several biometric and phytopathological parameters (stem height, aerial biomass, root biomass, wilting, chlorosis, pest and death) and macro and micronutrient composition were determined. The growth substrate was analyzed for several physicochemical (pH, CECe, and exchangeable cations, total C and N, P Olsen and availability of trace elements) and microbiological (community level physiological profiles: activity, richness and diversity) parameters. The use of the amendment, P. nigra plantation, and inoculation with rhizobacteria were the best techniques to reduce toxicity and improve soil fertility, as well as to increase the plant survival and growth. Soil bacterial functional diversity was markedly influenced by the presence of plants and the inoculation with bacteria, which suggests that the presence of plant regulated the configuration of a microbial community in which the inoculated bacteria thrive comparatively better. The results of this study support the use of organic amendments, tolerant plants, and plant growth promoting rhizobacteria to reduce environmental risk and improve fertility of soils impacted by mining.

Comorbidities and concentration of trace elements in livers of European bison from Bieszczady Mountains (Poland)

European bison is a species for which health monitoring is essential in conservation activities. So far, little research has been carried out on the concentration of elements in this species. Most previous studies did not associate the concentration of elements with susceptibility to diseases. In this study we investigate the relationship between comorbidities in European bison and concentrations of a wide spectrum of elements in the liver. Samples were collected during the monitoring of the European bison population in Bieszczady (southeast Poland) over the 2020–2022 period. Each individual was also visually inspected by a veterinarian in the field for the presence of lesions as a part of a post-mortem examination. The animals were divided into 3 groups: group A—one type of clinical sign; group B—two types of clinical signs; group C—three or more types of clinical signs. The ICP-OES method was applied to assess the concentration of 40 elements in livers. Discriminant analysis showed clear differences between the mineral status of individuals in the groups with one, two, and at least three types of clinical signs. Detailed analysis of selected elements showed that, in the case of eight elements, there was a relationship with age, sex, or comorbidities. Cu, Se, and Zn showed significant differences in relation to comorbidities, but only Cu concentration was lower when the frequency of lesions was higher. We concluded that in research on the mineral status of the population, apart from the availability of trace elements in the environment, the health condition of the studied individuals should also be considered. However, inferring the mineral status of the population on the basis of randomly obtained samples from dead individuals may give an incomplete view of the population, especially in the case of species susceptible to diseases, such as European bison.

The impact of heavy metal contamination on soil quality and plant nutrition. Sustainable management of moderate contaminated agricultural and urban soils, using low cost materials and promoting circular economy

A three-year experiment was conducted over six different soils, from northern and central Greece. The soils samples derived from both rural and urban environments, and they were moderately contaminated with heavy metals (Cu, Cd, Pb, Zn). Experiments were carried out by adding crop residues of wheat straw, cultivated in the plain of Thessaly, in the soil samples. Preliminary experiments were carried out to find the optimal mixing ratio of straw with soils, as well as the cut size, the temperature and humidity of the straw before its incorporation. The addition of wheat straw caused significant changes in the visual, physical, chemical, nutritional and microbiological quality indices of the soils studied. The indices related to the fertility and nutritional capacity of the soil samples were, in most cases, significantly improved, enhancing the soil health. Furthermore, the use of the straw reduced the availability of toxic metals, increasing, on the other hand, the availability of trace elements. Although the use of straw for improving soil properties has been known since ancient times, its use for polluted soil remediation is a matter of concern. A significant number of environmental and economic problems could be addressed if the principles of the circular economy were taken into account by decision-makers. Wheat straw, could be a key factor for soil health improvement, increasing its fertility and limiting the risks of toxic pollutants.

Effect of incubation time of three single extraction procedures on trace element extraction from sediment and soil.

The use of standard single-extraction procedures to evaluate the mobility and availability of trace elements is a common practice in most laboratories dealing with soil or sediment analysis. Most standard single-extraction procedures describe incubations last for 2h. However, these were tested and validated for soil analysis. Applying them for sediment analysis without further investigation might be misleading and should be reviewed with care. This paper investigates the effect of incubation time on the extraction efficiency of three standard single-extracting reagents (0.01M CaCl2, 1M NH4NO3, and 0.05M EDTA). Incubation experiments with sediment and soil samples lasting for 2h, 10h, and 10 d were performed. The results indicated that 2h appears sufficient to reach equilibrium using CaCl2 or NH4NO3 for soil analysis; but when analyzing sediments, incubation for 10 d resulted in higher concentrations. Incubation experiments with 0.05M EDTA showed that incubation for 2h was enough to extract Cd from the soil sample, Mn and to a lesser extent Cd from the sediment samples; while for the other elements, incubation for 10 d yielded higher concentrations for both sample types compared to that obtained after 2h and 10h separately. Relative to the pseudo-total metal contents, more than 55% of all studied elements were extracted by using 0.05M EDTA, indicating high bioavailable metal fraction.

COMPARISON OF EXTRACTANTS FOR ASSESSING Fe, Mn, Cu AND Zn AVAILABILITY IN SOILS

The available status of Fe, Mn, Cu and Zn in two soils (Melandaha-Silt loam and Dhamrai-Silty clay loam) was determined by two extraction methods (0.5 M DTPA and 0.1 N HCI). The soils previously treated with various composts and/or compost plus fertilizer and Amaranthus was grown upto 42 days. After harvest of Amaranthus, the soils were extracted with 0.5 M DTPA and 0.1 N HCI and the extracts were analyzed for trace elements contents. The availability of trace elements varied significantly with the extractants used and the highest values were found for 0.1 N HCI.

Cover Image, Volume 114, Issue 5

On the cover: North Shore Country Club in Glenview, IL routinely uses biosolids to improve turfgrass and soil health. In the article, “Assessment of availability of trace elements in turf soil after biosolids application” by Johnston et al., the lawn outside the clubhouse was used as a site in their micronutrient study, but biosolids are used throughout the golf course as well. Photo credit: Theresa Johnston. image

Assessment of availability of trace elements in turf soil after biosolids application

AbstractSoil amendments rich in organic matter and micronutrients can benefit plants by increasing the availability of micronutrients. To evaluate changes in the availability of trace elements in biosolids‐amended soil, soil and plant samples were collected from six managed turfgrass locations across the Chicago metropolitan area that received air‐dried biosolids topdressing at two rates: 2.2 Mg ha–1 per application (low biosolids rate), 11 Mg ha–1 per application (high biosolids rate), and urea 48.8 kg ha–1 total N per application (control). The low and high rates refer to biosolids total N and plant‐available N, respectively, considered for meeting the turfgrass N recommendation. Biosolids and urea application was conducted for each year of 2006–2008 with multiple applications per year. For micronutrients tested, biosolids application increased concentrations of soil‐available (Mehlich‐3 extraction) Zn (29.5 ± 2.9 mg kg–1, mean ± SE) and Cu (9.0 ± 0.6 mg kg–1) for the high rate vs. the control (10.4 ± 2.9 mg kg–1 for Zn and 6.1 ± 0.7 mg kg–1 for Cu). Soil‐available Mn, Fe, and Mo in the biosolids treatments did not differ from the control. Application of biosolids increased turf plant Cu, Zn, Mn, and Mo concentrations for both 2007 and 2008 and Fe for 2007 vs. the control with statistical significance at the high rate of biosolids. Topdressing with a plant‐available N‐based application rate for biosolids increased turfgrass nutrition of micronutrients without a concern of heavy metals.

Background levels of DTPA-extractable trace elements in calcareous soils and prediction of trace element availability based on common soil properties

Background levels of trace elements (TEs) are a crucial reference to assess the effects of human activity on soils globally. Traditionally background levels based on total TEs have been determined. However, levels of available TEs, the quantity of TEs that affects soil organisms and plant growth, have much greater relevance for biogeochemical processes. Therefore, here we determined background levels of diethylenetriaminepentaacetic acid (DTPA)-extractable contents of nine TEs in 100 soil samples from a region in Western Iran dominated by calcareous soils that has experienced low levels of human activity. Background levels determined using the iterative 2-δ technique were as follows (with comparable results using the distribution function method): Mn 11.6, Fe 6.9, Pb 1.6, Cu 1.1, Ni 0.6, Zn 0.6, Co 0.4, Cd 0.3, and Cr 0.1 mg kg−1. We further assessed how much of the variance in percentage available of total TE levels (DTPA-extractable fractions) can be explained by common soil properties. Unsurprisingly, pH and calcium carbonate equivalency were crucial parameters and for example explained 34 % of Cr availability. Electric conductivity and clay/sand content were equally important and explained 28 % and 35 % of Cu and Ni availability, respectively. The factor that explained most of the variance across all TEs was the soil organic matter content (explained for example 41 % and 21 % of Mn and Zn availability). Interestingly, the DTPA-extractable fractions of Cu, Mn, and Ni increased 4-fold and Zn 2-fold with an increase in organic matter (OM) content from 0.1 to 2 % in such high-pH soils. Multiple linear regression modelling using common soil properties reliably predicted TE availability (R2 values for measured versus predicted availability 84–93 %). These findings could help understand and predict TE behavior in calcareous soils and guide management practices.

Hydroxypyridinones in nitrogen-fixing bacterial cultures: a metal buffer for molybdenum and simulation of natural conditions.

Organic matter regulates the availability of important trace elements in aquatic and terrestrial ecosystems by acting as a source and container for microbes. To overcome the limitation of trace elements, nitrogen-fixing bacteria, e.g. release low-molecular-weight chelators (metallophores), which scavenge the essential cofactors of the nitrogenase, iron, and molybdenum (Mo), via complexation and subsequent uptake. The formation of metallophores is triggered by limiting conditions, which must be replicated in the laboratory in order to study metallophores as a mediator in metal cycling. While ethylenediaminetetraacetic acid (EDTA)-based buffer systems for metal cations are well established, there is limited knowledge regarding the buffering of oxoanions such as molybdate in a bacterial growth medium. To mimic the availability of molybdenum in nature under laboratory conditions, this study created a Mo-buffer system for bacterial growth media of the model organisms Azotobacter vinelandii and Frankia sp. CH37. We investigated selected hydroxypyridinones (HPs) as potential molybdenum-chelating agents, determining the amount required for efficient molybdenum complexation by calculating speciation plots of the various candidate complexes in artificial growth media at various pH values. The Mo-maltol system was identified as an ideal, nontoxic molybdenum-buffer system. In the presence of the Mo-maltol system, the growth of Frankia sp. was limited under diazotrophic conditions, whereas A. vinelandii could acquire molybdenum through the release of protochelin and subsequent molybdenum uptake. The study paves the way for unravelling molybdenum recruitment and homeostasis under limiting conditions in bacteria.

Performance promotion of broiler chickens: the role of the food supplements

In order to increase egg and chicken meat production, poultry growth is critical. The purpose of this study is to see how well broiler chickens perform when provided different additives in their meals (trace minerals and vitamins). Nutraceuticals, in addition to providing nutritional requirements for birds, offer advantageous pharmacological effects, such as assisting in the establishment of normal state of physiological health, preventing various diseases, and thus improving production performance. The vitamins, polypeptides and amino acids, minerals, enzymes, and other nutraceuticals are examples. Vitamins are dietary substances that are required for vital cell functions such as cell development, growth, and metabolism process. Mineral nutrition is critical in broiler chicken production, with an emphasis on manganese (Mn), zinc (Zn), selenium (Se) and copper (Cu). Due to the availability of organic trace elements and today''s fast-growing birds, broiler chickens'' Mn, Zn, Se, and Cu requirements must be revised.

Influence of micronuitrients on cadmium toxicity

There is growing evidence that micronutrient intake can lead to the development of poisoning and carcinogenesis caused by various chemicals. The article considers the question of the influence of the status of micronutrients on the toxicity of cadmium. After analyzing the literature data from both Russian and foreign databases (Scopus, Web of Science, RSCI), it was found that this topic on the effect of trace elements on the toxicity of heavy metals is relevant for scientists of various profiles.Cadmium interacts with the metabolism of four metals necessary for a balanced diet: Zn, Fe, Ca, and Cu. As can be seen from the analysis of literature sources, one of the important aspects of cadmium metabolism is its interaction with the sulfhydryl protein metallothionein.Like heavy metals, micronutrient availability in soil is affected by a number of factors. First, the availability of trace elements is directly or indirectly determined by the physicochemical and biological properties of the soil, such as pH, redox potential, soil organic matter content, complexing ligands, and underground biotic interactions. Based on the literature data, and analyzing the data obtained, it can be concluded that this issue remains relevant to this day. There have been few studies specifically designed to investigate the effect of micronutrient status on toxicity from non-essential metal exposure.Thus, many factors other than diet can greatly influence the metabolism of toxicants in the body, and require further research.

Agroecology niche for New Zealand's native earthworms

Exotic lumbricid earthworms have had some limited success colonising productive agricultural pastures in New Zealand, in place of native megascolecid species that did not adapt to the conversion from native vegetation cover. Native earthworms in lowland intensively-farmed landscapes are now almost entirely restricted to small fragments of native vegetation on marginal land where they coexist with adventive lumbricids. In recent years, regular pasture replacement using cultivation has been largely replaced by herbicide spray-out followed by direct drilling; much less soil disturbance potentially creates a new opportunity for native earthworms to colonise pastures. Reclaiming native earthworm habitat is critical not only to protecting diversity, but also to sustaining New Zealand's unique soil ecosystem services strongly associated to role of native species; however, there have been no studies related to this. Using a mesocosm experiment, we investigated how native and exotic earthworms modify physicochemical properties of a sheep-grazed pasture soil. The pasture soil was found to be equally suitable for the growth and survival of native and exotic species. Most burrowing earthworms increased the more soluble forms of macronutrients (N, P, S, K and Mg), but differences between native and exotic species were found to be larger than between functional groups. Two species of native earthworms, Octochaetus multiporus and Maoridrilus transalpinus, modified some soil properties in similar way to exotic species, but had significantly different impacts on pH, mineralisation of nutrients, and plant availability of trace elements. Compared to control, plant available N (PAN) and S concentrations were higher by more than 100% and 40%, respectively, in soils with presence of burrowing activity of the two native earthworms. Future co-existence of communities of native and exotic earthworms in agricultural pastures appears realistic, and this would benefit conservation of native species as well as dairy production. Further research may also reveal additional and unique benefits to soil quality that could be attributable to this formerly unavailable niche for native earthworms.

Soil-plant-animal Continuum Concerning the Certain Micro-mineral Status of Indigenous Sheep in Hot Semi-arid Regions

Background: Semi-arid regions have a large livestock population that grazes on nutrient-depleted natural grasses and crop leftovers, resulting in mineral shortages. The goal of this study was to determine the amounts of iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) in soil, pasture and sheep serum in semi-arid areas with low rainfall (498-522 mm) in order to construct a soil-plant-animal continuum and recommend solutions to increase trace element availability. Methods: Samples were collected from different parts of the continuum [Soil (n=50), pasture (n=50) and blood samples from sheep (n=50)] from the selected study area and the trace elements were analyzed after digestion using atomic absorption spectrophotometer. Descriptive, correlation and t-test analyses were carried out to categorize the deficiency, their significance and soil-plant-animal continuum. Result: Although most soil samples were found to be below threshold levels, most straws and stovers in the field had marginal levels of these micro-minerals. Most sheep serum samples had levels of different micro-minerals that were below the threshold level, implying that many indigenous sheep are deficient in micro-minerals. Although there was a substantial association between feed, fodder and sheep serum, there was no such correlation between trace mineral levels in sheep serum and soil. A higher percentage of these micro-minerals in sheep faeces implies that these nutrients are truly recycled through faeces and urine in semi-arid rural areas. To address the sub-clinical micro-mineral insufficiency in semi-arid regions, micro-mineral supplementation, particularly Zn, Cu and Mn, is required.