Varying Moisture Conditions Research Articles

Evaluating rehabilitation efforts following the Milford Flat Fire: successes, failures, and controlling factors

Uncontrolled wildfire in arid and semiarid ecosystems has become an increasing concern in recent decades. Active rehabilitation of fire‐affected areas is often quickly initiated to minimize long‐term ecosystem damage. However, the complex soil‐geomorphic‐vegetation patterns and low and variable moisture conditions in these regions makes restoration challenging. To further inform these post‐fire management decisions, we present results from 5 years of vegetation and sediment flux monitoring following the Milford Flat Fire in west‐central Utah, USA. Our sampling design includes monitoring plots in areas not burned, areas burned but where no rehabilitation was attempted, and burned areas where various rehabilitation approaches were implemented. At each of the 25 plots, vegetation cover and composition data were collected annually, and wind‐driven sediment flux was measured using passive dust traps. To evaluate effectiveness of post‐fire rehabilitation treatments in establishing desired species and limiting dominance of undesired species, we analyzed the temporal response of individual species and functional groups as well as community‐level multivariate responses. The warm and dry conditions that persisted for approximately 12 months post‐treatment, coupled with the surface disturbing rehabilitation approaches used, resulted in near‐surface dust fluxes several orders of magnitude higher in treated areas than in unburned or burned areas where no rehabilitation occurred. These dry conditions and high surface sediment flux limited the establishment of seeded species in rehabilitation areas for nearly 3 years. Post‐fire rehabilitation did not limit dominance by invasive annual species of concern. Perennial species composition in the areas burned but not subject to post‐fire rehabilitation was relatively similar to unburned throughout the study period. In contrast, the burned plots where rehabilitation was attempted were characterized by no (<3%) perennial cover or, in response to moister conditions, seeded forage species. These results suggest the post‐fire rehabilitation efforts conducted in the lower elevation regions affected by the Milford Flat Fire were not generally successful. Though dry conditions are likely to blame for the lack of success, the low and variable precipitation characteristic of these regions suggest future post‐fire rehabilitation decisions must assume that precipitation is going to be insufficient and plan rehabilitation efforts that are resilient to dry conditions.

SAXS studies on silica nanoparticle aggregation in a humid atmosphere

The influence of varying moisture conditions on the properties of amorphous silica nanoparticles was investigated. 10 nm silica particles in powder form were measured by small-angle X-ray scattering at different relative humidities ranging from 20 to 84 % at 45 °C. The data were analyzed using the generalized inverse Fourier transform method which enables separation of intra- and interparticle contribution to the scattering intensities. The former accounts for shape, size, homogeneity, and polydispersity of scattered nanoscaled objects, the latter describes the forces acting between the particles in the system. Formation of a water layer, of a thickness depending on the water content, covering the silica spheres has been detected. The pair correlation function derived from the structure factor shows a higher degree of structural order with increasing relative humidity. A model of ordering of silica nanoparticles is proposed.

Towards on-the-go field assessment of soil organic carbon using Vis–NIR diffuse reflectance spectroscopy: Developing and testing a novel tractor-driven measuring chamber

Proximal sensing of soil organic carbon (SOC) in the field using diffuse reflectance spectroscopy is still difficult under variable weather conditions. Here, we introduce a tractor-driven measuring chamber for on-the-go visible and near-infrared diffuse reflectance spectroscopy (Vis–NIRS) meeting experimental and precision agriculture demands. A commercial full-range spectrometer operates in a closed dark chamber with artificial light. Sensor view angle, distance to soil, and illumination conditions were optimized. The mobile chamber was placed on drum rollers to flatten the ploughed and tilled soil surface and to minimize disturbances in Vis–NIR spectra by surface roughness. Prior to on-the-go spectra acquisition under field conditions, SOC prediction models for the soils under study were independently calibrated under variable moisture and roughness conditions. Driving at a tractor velocity of 3kmh−1 resulted in measuring spots of approximately 8cm length and 3cm width at 0.6m distance to one another in the direction of movement, delivering geo-referenced SOC concentrations at a sub-m spatial resolution. Gravel on the soil surface resulted in erratic extremes of predicted SOC concentrations, but these could be eliminated as outliers. The system was tested under field conditions on two long-term experiments at two different sites which revealed each a large span of SOC concentrations. On-the-go predicted SOC concentrations and those obtained from conventional plot-wise lab analyses were correlated with coefficients of determination of R2=0.65 and a standard error of 1.22g SOCkg−1. Further improvements, particularly in data processing, will enable a reliable proximal sensing on-the-go for precision agriculture purposes in the near future.

Measuring Near‐Surface Soil Thermal Properties with the Heat‐Pulse Method: Correction of Ambient Temperature and Soil–Air Interface Effects

Large temperature gradients and proximity to the soil–air interface affect the measurement accuracy of thermal properties with the heat‐pulse probe (HPP). The objective of this study is to improve the HPP methodology for measuring soil heat capacity (C) and thermal conductivity (λ) in the surface soil layer by reducing the effects of ambient temperature variation and the soil–air interface. Thermal properties of eight soil layers (0–6, 2–6, 6–12, 12–18, 18–24, 24–30, 30–36, and 36–42 mm) were measured with the HPP in a loamy sand soil in two experiments with varying moisture conditions. Results were compared with values estimated with the de Vries models. Temperature drift caused by natural warming and cooling was removed from the observed trend of ambient temperature change with time. The influence of the soil–air interface was taken into account with a new solution using pulsed infinite line source theory with adiabatic boundary conditions. When ambient temperature change was considered, the HPP were capable of providing reasonable thermal property results at soil depths greater than 6 mm. For the 0‐ to 6‐mm depth layer, the HPP signals were affected simultaneously by ambient temperature drift and the soil‐air interface, and mixed scenarios were produced. Around midday, the HPP temperature by time curves were distorted so seriously that the effect of ambient temperature drift could not be removed. At other times, large errors were observed in the estimated C and λ data, even when ambient temperature drift was removed. When the effect of the soil–air interface was accounted for, however, C and λ measurement accuracies in the 0‐ to 6‐mm layer were improved significantly. The RMSE of C was reduced from 0.43 MJ m−3 °C−1 to 0.29 MJ m−3 °C−1 in Exp. 1, and from 0.52 MJ m−3 °C−1 to 0.34 MJ m−3 °C−1 in Exp. 2. Significant error reduction was also observed in λ measurements. Thus, to obtain accurate field measurements of shallow soil thermal properties, the ambient temperature drift and the impact of the soil–air interface must be properly taken into account.

Reproductive and Fiber Quality Responses of Upland Cotton to Moisture Deficiency

Quantitative information between water deficit and cotton (Gossypium hirsutum L.) reproductive potential and fiber quality is needed to improve cotton model predictability. An experiment was conducted by seeding Upland cotton cultivar, Texas Marker (TM)‐1, in sunlit growth chambers. Four water stress treatments, 100, 80, 60, and 40% of daily evapotranspiration of the control, were imposed during flowering for plants grown at optimum temperature and nutrient supply. Soil moisture content and midday leaf water potential (LWP) were measured twice weekly during treatment period. Photosynthetic measurements taken during the stress treatments were correlated with midday LWP. New flowers and bolls were tagged daily to estimate boll maturation period (BMP). Plant‐ and boll‐component dry weights were recorded at end of the experiment. Lint sample collected, grouped based on average LWP during BMP, were analyzed for fiber quality parameters. Declining photosynthetic rates as plants experience water deficits were mostly to stomatal limitation, but non‐stomatal factors played a role as stress progressed. Seedcotton and seed weight, boll numbers, and total biomass declined significantly at severe water deficit treatments reflecting declining trends of photosynthesis. Fiber length, strength, and uniformity declined linearly with decrease in LWP, whereas fiber micronaire increased with decrease in LWP. Fiber strength was most responsive to changes in LWP followed by micronaire, length, and uniformity. Immature fiber content increased and fiber maturity ratio declined with diminishing LWP. The functional relationships between LWP and fiber properties will be useful to develop fiber sub‐models under optimal temperature and nutrient, but varying moisture conditions.

A theoretical analysis of microbial eco-physiological and diffusion limitations to carbon cycling in drying soils

Soil microbes face highly variable moisture conditions that force them to develop adaptations to tolerate or avoid drought. Drought conditions also limit the supply of vital substrates by inhibiting diffusion in dry conditions. How these biological and physical factors affect carbon (C) cycling in soils is addressed here by means of a novel process-based model. The model accounts for different microbial response strategies, including different modes of osmoregulation, drought avoidance through dormancy, and extra-cellular enzyme production. Diffusion limitations induced by low moisture levels for both extra-cellular enzymes and solutes are also described and coupled to the biological responses. Alternative microbial life-history strategies, each encoded in a set of model parameters, are considered and their effects on C cycling assessed both in the long term (steady state analysis) and in the short term (transient analysis during soil drying and rewetting). Drought resistance achieved by active osmoregulation requiring large C investment is not useful in soils where growth in dry conditions is limited by C supply. In contrast, dormancy followed by rapid reactivation upon rewetting seems to be a better strategy in such conditions. Synthesizing more enzymes may also be advantageous because it causes larger accumulation of depolymerized products during dry periods that can be used upon rewetting. Based on key model parameters, a spectrum of life-history strategies thus emerges, providing a possible classification of microbial responses to drought.

Newly Developed Adhesive Strength Test for Measuring the Strength of Sealant between Joints of Concrete Pavement

AbstractA new adhesive strength test (AST) was developed to determine the adhesive strength of joint sealant. A series of sealant thicknesses, displacement rates, and curing times was tested to determine proper AST testing parameters using self-leveling (SL) and non-self-leveling (NS) silicone sealants. A series of tests was conducted under varying moisture conditions. The results appeared to indicate that moisture may reduce adhesive strength. Drying-time tests were conducted to determine the approximate appropriate wait time between joint washing and sealant installation for 3.2 mm (1/8 in.) and 9.5 mm (3/8 in.) joints. A series of tests was also conducted on artificially aged sealants, which appeared to indicate that oven aging reduces adhesive strength for SL sealant. Non-self-leveling sealant, on the other hand, appeared to be largely unaffected by oven aging. Hot-water aging and freeze-thaw aging appeared to reduce adhesive strengths for both sealant mixtures.

Variability of riparian soil diatom communities and their potential as indicators of anthropogenic disturbances

Riparian soils are affected by both natural and anthropogenic disturbances occurring in the water bodies and on the catchment area. These riparian areas are also rich in microhabitats and therefore host various soil biota, including diatoms. Diatoms are known for their bioindication abilities in water and could potentially be used in that context in the riparian zone. Therefore the possibility of riparian soil diatoms acting as indicators of both terrestrial and aquatic disturbances is worth discussion. We analysed diatom community structure and their variability between different study areas and sites. We also quantified diatom species diversity and richness and evenness of the riparian topsoils. Possible effects of various anthropogenic disturbances on diatom communities, alkaline air pollution, and the effects of mining waters pumped into the area were studied in north- eastern Estonia. These results were compared with results from an area with low human influence in south-eastern Estonia. Additionally, we evaluated the potential of diatoms as indicators of various anthropogenic disturbance levels and a water contamination gradient based on sulphate concentrations. Community parameters, including species richness, diversity, and evenness, indicated some differences between the studied communities both when the separate study sites and distinguishable anthropogenic disturbance levels were compared. Diatom assemblages also showed moderate variability between the study sites, which could be influenced by variable moisture conditions, variable organic matter content, and the trophic level of the water body. Despite the variable levels of human influence the two compared areas shared about 51.4% of the species. Our findings show that the diatom community composition of riparian soils could potentially indicate anthropogenic disturbance levels, especially through the abundance, absence, or presence of specific species (e.g. Hantzschia amphioxys, Fragilaria zeilleri var. elliptica, Pinnularia lata).

Persistence traits in perennial pasture grasses: the case of phalaris (Phalaris aquatica L.)

Persistence is consistently claimed by Australian farmers as a high priority for perennial grasses in long-term pastures. Phalaris (Phalaris aquatica L.) is a productive perennial grass with proven persistence in south-eastern Australia. Nevertheless, factors that determine the persistence of pasture species in southern Australia related to climate (drought), soil (acidity), grazing pressure, and, importantly, their interaction can reduce persistence of phalaris and other species in various situations. These factors and their interactions are discussed in this review, and strategies to improve persistence with emphasis on plant breeding approaches are considered, with the most durable outcomes achieved when breeding and management options are employed concurrently. Two examples of breeding to improve persistence traits in phalaris are described. A program to improve acid-soil tolerance resulted first in the release of cv. Landmaster, and recently Advanced AT, which is the most aluminium (Al)-tolerant cultivar of phalaris to date. It was bred by recurrent selection on acid soils in a population containing genes from a related, more Al-tolerant species, P. arundinacea. The higher Al tolerance of cv. Advanced AT is of most benefit in more assured establishment on acid soils under variable moisture conditions and confers improved flexibility of sowing date. Cultivar Holdfast GT was bred to address complaints of poor persistence under heavy grazing by cultivars of the highly productive, winter-active type, since high grazing tolerance is needed to achieve profitable returns from developed pastureland. Evidence of good persistence under grazing for cv. Holdfast GT and possible tradeoffs with productivity are discussed. Maintaining high productivity under a predicted higher incidence of drought stress (climate change) and increasing areas of acid soils presents ongoing challenges for persistence in pastures.

Nitrogen Fate and Transport in a Conventional Onsite Wastewater Treatment System Installed in a Clay Soil: Experimental Results

Relationships between N transport and hydraulic function of onsite wastewater treatment systems (OWTSs) in clay‐textured soils are largely unknown. The objectives of this study were to quantify N concentrations in a clay soil and estimate denitrification in the vadose zone beneath a conventional OWTS. An OWTS installed in the Piedmont region of Georgia was dosed with residential strength wastewater three times per day for 2 yr. Soil near trench bottoms cycled between saturated and unsaturated conditions under the dosing schedule we used. Mean NH4–N concentrations decreased to <1 mg L−1 within 90 cm of trench bottoms due to adsorption, immobilization, and nitrification. Mean NO3–N concentrations increased as the drainfield matured and ranged from 10 to 25 mg L−1 near the end of the two year study period. Mean pressure heads and Cl− concentrations measured at 3.3 m and 6.6 m from trench inlets indicated that significantly more water infiltrated the drainfield at the 3.3 m position. Wet conditions at the 3.3 m position may have restricted nitrification, while dry conditions at the 6.6 m caused rapid nitrification. Nitrogen:chloride ratios suggested that 61% of N entering the drainfield was lost, potentially as volatile N‐species. The 30‐cm zone directly beneath the trenches had high biomass N and C contents (15 mg kg−1 N and 60 mg kg−1 C) and was presumably the most biologically active zone. The fate and transport of N was dynamic in this system due to variable moisture conditions near the trench‐soil interface which may have intermittently stimulated denitrification.

Forced air plasma treatment for enhanced adhesion of polypropylene and polyethylene

This paper describes our investigation of the effects of forced air plasma treatment on polypropylene and polyethylene. The morphology of the treated surfaces has been carefully examined using a variety of tools including optical profiling. The complex surface morphology was observed to change with increasing treatment and varying intensity of the treatment over the surface. Optimum treatment conditions have been deduced using surface energy determinations and can be compared with the morphological changes. Determinations of surface energy, both the polar and non-polar components, have been made after exposure to varying moisture conditions for varying times. Different results are obtained for different environments and from different materials. These results demonstrate that forced air plasma treatment is a highly effective means of increasing the surface energy of polymers, which can be long-lasting, provided the treated surfaces are kept in dry conditions.

Spring and summer patterns in flowering onset, duration, and constancy across a water‐limited gradient

Community-level flowering patterns can be characterized by onset, duration, and end as well as constancy, the degree to which species commence, cease, and reinitiate flowering within a season. In the mountainous Sky Islands region of the southwestern United States, flowering onset is clearly influenced by elevation in the spring, but much less so in the summer season. We evaluated whether these flowering metrics reflect these dissimilar patterns between distinct spring and summer seasons regarding the influence of the elevation and moisture gradient. • We characterized flowering onset, end, duration, and constancy by plant functional type and their relationships to climate variables in spring and summer. We also evaluated the influence of climate on seasonal flowering patterns. • Gaps in seasonal flowering occur frequently in this system in both seasons and among all plant functional types. In both seasons, annual plants exhibit the shortest flowering durations and highest constancies, and plants at low elevations, inhabiting environments with variable moisture conditions, show a greater tendency for longer flowering durations and lower constancy than high-elevation plants. Spring flowering characteristics are most influenced by the total amount of October-March precipitation as well as temperatures in these months, whereas summer flowering characteristics are influenced by the timing of summer-season precipitation, and next by the total amount of summer precipitation. • Flowering metrics, especially constancy and duration, show similar patterns in spring and summer and vary across elevation and moisture gradients. These patterns have substantial implications for plant and animal communities.

Drought response of some tropical rice genotypes: Rooting, vegetative traits and grain production

Sixteen upland rice varieties, comprising of some interspecific New rice for Africa (NERICA) hybrids, established varieties and some breeding lines, were raised in the greenhouse and used to expound drought response under varying moisture conditions, as a guide for breeding genotypes with appreciable drought tolerance and grain yield. Varieties were subjected to different levels of drought stress through different combinations of moisture regime and times of water application at different stages of growth. Varieties, moisture regime and times of water application espoused significant mean squares (MS) for root, vegetative and grain production. Times of water application consistently accounted for the largest percentage of mean squares (PMS) for most characters. Significant interaction was also obtained between variety, moisture regime and times of water application for most of the characters. There were significant correlations between times of water application and all the root, shoot and grain yield character. Fresh shoot weight, dry shoot weight, tiller number and leaf number were also positively correlated to moisture regime. WAB 880 recorded the largest mean value for root volume and thickness and hence better drought adaptation but this failed to translate to superior grain production. ITA 150, an established variety, however recorded the highest panicle number and grain production compared to WAB 880 and the NERICA varieties. The need for further introgression of genes from ITA 150 into newly developed NERICA varieties through an intricate combination of favourable genes for improved drought tolerance and better grain production was canvassed. Key words: Drought tolerance, interspecific hybrids, root and vegetative traits, grain yield.

Strength prediction of adhesive joints after cyclic moisture conditioning using a cohesive zone model

This paper presents a methodology to predict the strength of adhesive joints under variable moisture conditions. The moisture uptake in adhesive joints was determined using a history dependent moisture prediction methodology where diffusion coefficients were based on experimental cyclic moisture uptake of bulk adhesive samples. The predicted moisture concentrations and moisture diffusion history were used in a structural analysis with a cohesive zone model to predict damage and failure of the joints. A moisture concentration and moisture history dependent bilinear cohesive zone law was used. The methodology was used to determine the damage and failure in aluminium alloy – epoxy adhesive single lap joints, conditioned at 50 °C and good predictions of failure load were observed. The damage in the adhesive joints decreased the load carrying capacity before reaching the failure load and a nonlinear relationship between the load and displacement was observed. Changes in crack initiation and crack propagation were also observed between different types of joints. The presented methodology is generic and may be applied to different types of adhesive joint and adhesive.

Evaluating the use of weathering indices for determining mean annual precipitation in the ancient stratigraphic record

Different quantitative methods have been developed to determine paleo-rainfall using paleosols. Of particular interest are methods that use bulk geochemistry to calculate a weathering index and, from that, mean annual precipitation. Twenty-three paleosols that formed during a time of significant climate change—the Paleocene–Eocene Thermal Maximum (PETM)—were analyzed to evaluate the relative merits of two geochemical proxies that have been developed for estimating paleoprecipitation: one depends on the chemical index of alteration without potash (CIA-K) and the other uses the CALMAG weathering index, which depends on CaO and MgO. The paleosols are located in the Paleogene Fort Union and Willwood formations in the Bighorn Basin, WY. Morphologic differences among the paleosols indicate that they formed under varied soil moisture conditions. A morphology index was developed from pedogenic features that are sensitive to soil drainage, and thus to rainfall, to assess that variability. Quantitative mean annual precipitation (MAP) values were calculated for each paleosol using the CIA-K index and the CALMAG index, which was developed specifically for Vertisols. Those results were compared to the morphology index for 23 paleosols. The results indicate that increases and decreases in MAP calculated from both methods correlate relatively well to changes in the soil morphology index; however, the results from the CALMAG weathering index show a stronger correlation. The results suggest that the CALMAG proxy provides a more robust MAP estimate for Vertisols. In addition to comparing MAP estimates to the soil morphology index, we compared the MAP values to paleorainfall estimates determined from paleofloras at the same stratigraphic levels as three of the paleosols. That comparison confirms that the CALMAG method is reliable for reconstructing MAP from ancient Vertisols. The results also show that, in the Bighorn Basin, Vertisols with a B horizon < 1 m thick should not be used to determine MAP. Thinner paleosols have had less time for weathering and may not have cation distributions representative of precipitation.

Wood decomposing abilities of diverse lignicolous fungi on nondecayed and decayed beech wood

We tested the decay abilities of 28 isolates from 28 lignicolous fungal species (Basidiomycota, Ascomycota and Zygomycota) with the pure culture test. We used beech wood powder in varying moisture conditions and decay stages (nondecayed, intermediately decayed and well decayed) as substrates. The weight loss in wood powder was –0.2–17.8%. Five isolates of Basidiomycota (Bjerkandera adusta, Mycena haematopus, Omphalotus guepiniformis, Trametes hirsuta, Trametes versicolor) caused high weight losses in nondecayed wood. We detected significant effects of decay stage on weight loss in wood in most isolates tested, whereas moisture content rarely had an effect on weight loss. Among Basidiomycota and Xylariaceae in Ascomycota weight loss was greater for nondecayed wood than for intermediately and well decayed wood. In contrast four isolates in Ascomycota (Scytalidium lignicola, Trichoderma hamatum, T. harzianum, T. koningii) caused substantial weight loss in intermediately and well decayed wood, although they rarely caused weight loss in nondecayed wood. Zygomycota caused low weight loss in wood. Wood decay stages also affected decomposition of wood chemical components. Acid-unhydrolyzable residue (AUR) decomposition was reduced, whereas holocellulose decomposition was stimulated by some strains of Basidiomycota and Ascomycota in well decayed wood. T. harzianum in particular caused significant weight loss of holocellulose in well decayed wood, although this fungus caused negligible weight loss of both AUR and holocellulose in nondecayed wood. We discuss these changes in the decay patterns of AUR and holocellulose with varying wood decay stages in relation to the role of fungal decomposition of woody debris in forests.

Polymer-Modified Mortars for Corrosion Protection at Offshore Wind Energy Converters

The importance of renewable energy for our world’s energy supply is steadily increasing. Starting last year, offshore wind parks are being developed along the German coastline following the success achieved in the onshore wind energy. The first German offshore wind energy park is be erected on the Alpha Ventus test field near the isle of Borkum, where the depth of the sea amounts to 30 meters. Due to the hazardous conditions associated with the sea water, many challenges regarding corrosion control have to be met. With the combined effects of sea water, varying moisture conditions and impact damages caused by ice and flotsam, the conventional methods of corrosion protection with mean thicknesses of 1000 μm will not suffice to protect the steel for an operating life expectancy of 25 years. As a result, the thickness of the various construction elements need to be increased beforehand leading to an excessive usage of steel. For the new corrosion protection system presented in this paper, a layer made of high performance mortar with a thickness of about ten millimeters will be sufficient to protect the steel. To unfold its protecting effect, the mortar needs to comply with stringent requirements such as exhibiting high resistance to chloride ingress, frost and abrasion.

Deterioration of FRP/concrete bond system under variable moisture conditions quantified by fracture mechanics

Fiber reinforced polymer (FRP) retrofit systems for concrete structures have been widely used, and studies on their short-term debonding behavior have been extensively conducted. Nevertheless, long-term performance and durability issues regarding debonding behavior in such strengthening systems still remain largely uncertain and unanswered. Due to its composite nature, the effectiveness of the strengthening system largely depends on the properties of the interface between the three constituent materials, namely concrete, epoxy, and FRP. Many factors can cause degradation of the interface properties, especially environmental exposure during service life. In this study, effects of moisture on concrete/epoxy/FRP bond system is characterized by means of the tri-layer fracture toughness, which can be obtained experimentally from peel and shear fracture tests. An irreversible weakening in bond strength has been observed in fracture specimens under moisture cyclic condition. Based on the experimental results of fracture specimens under variable moisture conditions, an empirical model can be developed to predict service life of FRP-strengthening system.

PREDICTION OF THE ANTICLASTIC SHAPE CHANGES OF HYBRID COMPOSITE MATERIAL

In search of structurally better and aesthetically more attractive solutions of the erection of various structures, non‐standard anticlastic elements are used more frequently. Therefore preservation of the initial shape of timber composite material sheets by using of reinforced plastic reinforcement has been investigated. Calculation model for determination of the thickness of rational reinforcement anticlastic sheet, which provides change of the original bending radius under variable moisture conditions (Baikovs and Rocens, 2006) within the limits of preferable intervals is developed by authors and using finite element method, calculations and modelling of sheet deformations are carried out with software package ANSYS v.11 (henceforth FEM) and by developed analytical method. Comparative research of the results calculated with the FEM and developed calculation model showed that the difference between results in the three cases investigated, when the composite timber material is reinforced on the top, bottom and both sides for the most of the cases does not exceed 3.3%. An opportunity to provide the original shape of anticlastic timber composite material sheets by using glass fibre reinforced plastic reinforcement under variable moisture conditions and not exceeding the difference of 5% has been demonstrated. Santrauka Ieškant ivairiu konstrukciju statiniu konstrukciškai geresniu ir estetiškai patrauklesniu sprendiniu, dažniausiai naudojami nestandartiniai antiklastiniai elementai. Todel buvo tyrinetas medienos kompozitines medžiagos lakštu pradinio pavidalo išsaugojimas naudojant sustiprinta plastiko armatūra. Skaičiuojamasis modelis, padedantis nustatyti racionaliai armuoto antiklastinio lakšto stori, kuris pakeičia pradini lenkimo spinduli kintamomis dregmes salygomis (Baikovs, Rocens 2006) tarp priimtinu intervalu ribu, yra sukurtas autoriu ir, taikant baigtiniu elementu metoda, lakšto deformaciju skaičiavimai bei modeliavimas atlikti kompiuteriniu programu paketu ANSYS v. 11 (toliau ‐ FEM) ir pagal sukurta analitini metoda. Rezultatu, apskaičiuotu su FEM ir pagal sukurta analitini modeli, lyginamasis tyrimas parode, kad skirtumas tarp triju tirtu atveju, kai medienos kompozitine medžiaga yra armuota viršuje, apačioje ir iš abieju pusiu, rezultatai daugeliu atveju neviršija 3,3%. Parodyta galimybe suteikti originalu pavidala antiklastiniams medienos kompozitiniams lakštams naudojant stiklo pluoštu sustiprinto plastiko armatūra ivairiomis dregmes salygomis ir neviršijant 5% skirtumo.

Effect of Organic Amendments on the Proliferation Stability of Trichoderma harzianum and Suppression of Phytophthora meadii in Cardamom Soils in Relation to Soil Microflora

An even economical and more frequently used method of attaining biological control of soil borne plant pathogens is incorporating plant residues and organic amendments to the soil, which support high level of microbial activity. In the present study farm yard manure (FYM), poultry manure (PM), coffee husk (CH) and neem cake (NC) were used as soil amendments with or without Trichoderma harzianum to evaluate their efficacy in suppressing Phytophthora meadii under varying moisture conditions. The survival of Phytophthora was found higher at 50% moisture level. Neem cake with Trichoderma appeared as a suitable amendment at all moisture level and has shown 69% reduction in Phytophthora infection over control. At 75% and 100% (field capacity), no detectable level of Phytophthora was observed in treatments where T. harzianum was fortified with CH, PM and NC. At field capacity, PM and FYM with Trichoderma also reduced the build up of Phytophthora . Native population of Trichoderma was found negligible in non-amended treatments. All the four amendments maintained the population and supported the growth of Trichoderma at all moisture levels. In general, organic manures with T. harzianum reduced the population level of other fungi, while crop residues supported the growth of fungi like Penicillium, Rhizopus, Aspergillus, Mucor , etc. besides T. harzianum.