Effect Of Soil Moisture Content Research Articles

Effect of Soil Moisture Content and Phosphorus Application on Phosphorus Nutrition of Rice Cultivated in Different Water Regime Systems

Effect of Soil Moisture Content and Phosphorus Application on Phosphorus Nutrition of Rice Cultivated in Different Water Regime Systems

Effect of Soil Moisture Content on the Survival of Ganoderma Species and Other Wood-Inhabiting Fungi.

The survival of mycelia of Ganoderma australe, G. boninense, G. lucidum, and G. weberianum in colonized wood was measured in soils with different soil matrix potentials. Survival of mycelia of G. australe and G. boninense, which do not produce chlamydospores, buried in plots subjected to different soil moisture treatments, declined rapidly, and the fungi could not be recovered after 9 to 12 weeks. Survival of mycelia of G. lucidum and G. weberianum, which produce chlamydospores, rapidly declined from 0 to 15 weeks of incubation but consistently ranged from 35 to 50% after 15 weeks of incubation. In regression analyses for each of the four Ganoderma species, there was no difference in the rate of change of mycelial survival over time among different soil moisture treatments. However, when data from only the -0.20 MPa treatment were used, the rates of change of mycelia survival over time of G. australe and G. boninense significantly differed from those of G. lucidum and G. weberianum. G. australe and G. boninense were not recovered from pieces of infested wood subjected to 3 and 1 months of flooding, respectively. In treatments with lower soil moisture, the survival of these two fungi ranged from 80 to 90% over 2 years. In all soil moisture treatments, survival of G. lucidum and G. weberianum ranged from 80% to more than 90% over 2 years. Similarly, seven species of other wood-inhabiting fungi that do not produce chlamydospores were not recovered from pieces of infested wood subjected to 1 or 5 months of flooding, but chlamydospore-producing species were recovered. These results indicate that, regardless of chlamydospore formation, woody debris in soils harboring wood-decay fungi may be important for long-term survival, and chlamydospores of Ganoderma in woody debris enhance the resistance of the fungi to environmental stresses such as flooding. Flooding infested fields may help control those woodinhabiting fungi such as G. australe and G. boninense that do not produce chlamydospores.

Moisture supply and microclimate––interactions with productivity potential

Micrometeorological conditions within a crop canopy are important as direct environmental forces to photosynthesis and also for different microorganisms living in the plant ecosystem. Vertical profiles of air temperature, humidity, wind speed describe the micrometeorological conditions within the plant canopy. Those profiles depend on macrometeorological conditions and the structure and water status of the plant stand. A user friendly version of crop micrometeorological simulation model was developed concerning data assimilation and output analysis. The effect of soil moisture content was investigated on microclimatic conditions and further effects on photosynthesis intensity using simulation model. Different states of water supplies cause different measure of evapotranspiration and these differences appear in microclimate and formation of plant production.

The effect of soil moisture content on the sorption of five sterol biosynthesis inhibiting fungicides as a function of their physicochemical properties

The effect of soil moisture content on the sorption of five sterol biosynthesis inhibiting fungicides as a function of their physicochemical properties

Pengaruh Kadar Air Tanah Terhadap Pertumbuhan dan Produksi Dua Tipe Kapolaga Sabrang

Research of effect of soil moisture content on growth and production of cardamom was done in Lembang. Manoko research garden, from on November 1994 to July 1995. The aim of this research was to identify of the effect of soil moisture content growth and production of two types cardamom, were Mysore type and Malabar type. A factorial randomized block design with two factors, three replication was used, and each replication on one treatment contain three plants, and each plant planted in one polybag. The first factor was soil moisture content consisted five treatments at 30% AW, 45% AW, 60% AW, 75% AW, and 90% AW. The second factor was cardamom type is Mysore and Malabar type. Andosol soil type mixed animal manure with 2 : 1 ratio was used for plant media. NPK fertilizer application with 120 gram/polybag/year was used as basic fertilizer was given in three time. The first application as fertilizer given two week after planting (WAP). The second was given on February 1995 and June 1995. Soils were irrigated to varied water content, and all polybag moved to roof house. The third was on values of the tiller at Malabar type 4 WAP was found on 60% AW, shoot at 16 MST and 30 WAP. The highest values of rimpang was found on 15% AT, in Malabar type. Key word : Cardamon, Soil, Moisture content

The effect of soil moisture content on the sorption of five sterol biosynthesis inhibiting fungicides as a function of their physicochemical properties

We investigated the sorption of five widely used sterol biosynthesis inhibitor fungicides (SBIs: flusilazole, propiconazole, epoxiconazole, fenpropimorph and prochloraz) on a loam soil to assess availability of the SBI residues that are usually left in soil after crop treatments. We focused particularly on the soil moisture content effect, which is poorly documented and is difficult to investigate under realistic conditions. SBI sorption was determined (using diuron as a reference) at two soil moisture contents (26.1% and 46.6% w/w) over a period of 3 weeks using a direct soil solution sampling method. After 24 h of contact, <1% of each applied fungicide was recovered in the soil solution. Despite their low availability in the liquid phase, long-term sorption was observed for all the compounds, reducing concentrations in the soil solution and doubling the value of the partition coefficient. Significant effects of soil moisture on long-term sorption were observed, depending on the properties of the chemicals and the sorption mechanisms. Wershaw's humus model (humic substances have a membrane-like structure) was adapted to fit our observations. Low soil moisture content is assumed to modify the structure of humic substances and to generate hydrophobic surfaces, which favour sorption of hydrophobic fungicides (flusilazole, propiconazole and epoxiconazole). This effect is likely to decrease with the increase in the hydrophobic character of non-ionic pesticides. It becomes adverse for the more hydrophilic compounds (diuron), which are more sorbed at high soil moisture content due to their higher affinity for hydrophilic regions of humus and to diffusion. Soil moisture effects are more complex when compounds are likely to be protonated in soil. Weakly basic compounds (prochloraz) may partition rapidly into the liquid-like interior of humus at low soil moisture content but increased diffusion at high soil moisture content may cause additional sorption by ion exchange at colloid surfaces. Strongly basic compounds (fenpropimorph) may essentially adsorb due to ionic interactions with colloids, and their sorption is enhanced at high soil moisture content due to diffusion. Consequences for environmental fate and biological activity of pesticides are briefly discussed. © 2000 Society of Chemical Industry

Influence of environmental factors on glyphosate efficacy when applied to Avena fatua or Urochloa panicoides

Glasshouse experiments were conducted to determine the effects of soil moisture content, irradiance, temperature and relative humidity on the efficacy of glyphosate applied to six isogenic lines of Avena fatua L. (wild oat) and four near‐isogenic lines of Urochloa panicoides Beauv. (liverseed grass). The variables examined were four soil moisture conditions (29%, 42%, 55% and 100% of field capacity), two levels of irradiance (400 and 800 μmol m−2 s−1), two levels of relative humidity (&gt;92% and 65%) and four temperature regimes (20/15, 25/20, 30/25 and 35/30 °C: day/night), representing the environmental conditions of winter or summer fallows in the north‐east grain region of Australia. The efficacy of 360 g acid equivalent ha−1 glyphosate was greatest under well‐watered (100% of field capacity), warm (30/25 °C for A. fatua and 35/30 °C for U. panicoides) and humid (&gt;92/90%) conditions. The efficacy was least under severe water stress (29% of field capacity), warm (30/25 °C for A. fatua and 35/30 °C for U. panicoides) and moderately humid (65/60%) conditions. Efficacy was not altered by the level of irradiance nor was it different between isogenic lines.

The influence of soil moisture content on glyphosate efficacy for the control of annual grasses in fallow land

In order to determine the effects of soil moisture content on the efficacy of glyphosate, field experiments were conducted on three annual grass weeds [#Avena fatua

Effects of soil moisture content and temperature on methane uptake by grasslands on sandy soils.

Aerobic grasslands may consume significant amounts of atmospheric methane (CH4). We aimed (i) to assess the spatial and temporal variability of net CH4 fluxes from grasslands on aerobic sandy soils, and (ii) to explain the variability in net CH4 fluxes by differences in soil moisture content and temperature. Net CH4 fluxes were measured with vented closed flux chambers at two sites with low N input on sandy soils in the Netherlands: (i) Wolfheze, a heather grassland, and (ii) Bovenbuurtse Weilanden, a grassland which is mown twice a year. Spatial variability of net CH4 fluxes was analysed using geostatistics. In incubation experiments, the effects of soil moisture content and temperature on CH4 uptake capacity were assessed. Temporal variability of net CH4 fluxes at Wolfheze was related to differences in soil temperature (r2 of 0.57) and soil moisture content (r2 of 0.73). Atmospheric CH4 uptake was highest at high soil temperatures and intermediate soil moisture contents. Spatial variability of net CH4 fluxes was high, both at Wolfheze and at Bovenbuurtse Weilanden. Incubation experiments showed that, at soil moisture contents lower than 5% (w/w), CH4 uptake was completely inhibited, probably due to physiological water stress of methanotrophs. At soil moisture contents higher than 50% (w/w), CH4 uptake was greatly reduced, probably due to the slow down of diffusive CH4 and O2 transport in the soil, which may have resulted in reduced CH4 oxidation and possibly some CH4 production. Optimum soil moisture contents for CH4 uptake were in the range of 20 – 35% (w/w), as prevailing in the field. The sensitivity of CH4 uptake to soil moisture content may result in short-term variability of net atmospheric CH4 uptake in response to precipitation and evapotranspiration, as well as in long-term variability due to changing precipitation patterns as a result of climate change.

The Influence of Soil Moisture Content on the Bioavailability and Toxicity of Cadmium forFolsomia candidaWillem (Collembola: Isotomidae)

For Collembola living in the upper soil and litter layers, soil moisture is a primary factor for survival. In addition, a shortage or surplus of moisture might interact with other stress factors, such as persistent pollutants. The aim of this study therefore was to investigate the response of the collembolan speciesFolsomia candidato cadmium at different soil moisture contents. Tests were performed in an artificial soil substrate at soil moisture levels of 25, 35, 45, and 55%, corresponding with 74, 103, 132, and 162% of field capacity, respectively. Cadmium sorption to the soils, estimated from water-soluble concentrations, was not significantly affected by soil moisture content. Significant effects of soil moisture content were found for the toxicity of cadmium on body weight ofF. candidaafter 4 and 6 weeks. EC50s did, however, not differ by more than a factor of 2. Reproduction in the controls was strongly affected by soil moisture content, but EC50s for the effect of cadmium on reproduction did not differ for the different moisture levels. Cadmium concentrations in the animals were not significantly affected by soil moisture content. From this study it can be concluded that, within the range chosen, soil moisture content does not have a great influence on the bioavailability and toxicity of cadmium for the collembolanF. candida.

Effect of soil moisture content on the suppression of Rhizoctonia stem canker on potato by the nematode Aphelenchus avenae and the springtail Folsomia fimetaria

The effect of soil moisture content on the suppression of Rhizoctonia stem canker on potato by mycophagous soil animals was studied in growth chambers. Three soil moisture levels were established in two bioassays, in which potato sprouts grew through a 15‐cm soil layer inoculated with sclerotia of Rhizoctonia solani (AG‐3). In one experiment two levels of R. solani inoculum were applied. The effect on plant disease of mycophagous soil fauna was assessed by adding the springtail Folsomia fimetaria and/or the nematode Aphelenchus avenae to the soil. In the absence of mycophagous organisms, Rhizoctonia disease severity on potato stems was highest in dry soil. A. avenae and F. fimetaria reduced Rhizoctonia stem canker when applied at populations found in the field. They were effective over a broad range of soil moistures. The stimulatory effect of dry soil conditions on Rhizoctonia stem canker was counteracted by a greater efficacy of the mycophagous soil fauna under these conditions. Mild drought stress did not seem to be a limiting factor in the biological control of stem canker by these two organisms.

The effect of soil moisture content on the cellulolytic mycoflora of soil amended with cellulosic remains

The fungal population of soil amended with four types of cellulosic remains under different levels of water content was recorded. 40–80% soil water content was the best level for fungal multiplication. There was no specific fungal flora isolated from any of the three cellulosic remains but some fungi grew noticeably better on some cellulose types than on others. The gross total count of fungi was the highest in soil amended with sugar cane straw at 60% water content but the least was in soil mixed with broad bean straw at 100% water content. Aspergillus, Penicillium, Chaetomium, Cladosporium, Emerciella nidulans, Fusarium and Stachybotrys were the most dominant fungi. Sugar cane straw was the most hospitable cellulosic material for soil funig. 60% water content was more suitable for the cellulolytic activity of test fungi but protein content was the highest in between 60–80% of soil water content.

Predicting the Effect of Moisture on Vapor-Phase Sorption of Volatile Organic Compounds to Soils

Sorption from the vapor phase is an important factor controlling the transport of volatile organic compounds (VOCs) in the unsaturated zone. Accurate description of sorption from the vapor phase to soil in the unsaturated zone therefore is intrinsic to predicting the ultimate fate of contaminants. Vapor-phase sorption of several VOCs onto seven soils at oven-dried, air-dried, typical field moisture and water-saturated conditions was measured using a batch-equilibrium headspace method. An equilibrium partitioning model was developed to predict the effect of soil moisture content on vapor-phase sorption. The model was based on the soil pore-size distribution and BET isotherm sorption parameters under oven-dried and water-saturated conditions. The model was shown to accurately predict observed experimental results.

The effect of soil parameters on the radon concentration values in the environment

A study was made of the effect of soil moisture content and porosity on the diffusion of radon through soil. It was found that the diffused radon concentration decreases exponentially with the increase of soil thickness. The diffusion coefficient of radon through soil was found to decrease with the increase of the moisture content and to increase with the increase of porosity. A field study was also conducted to investigate the effect the above parameters on radon concentration values as measured at a depth of ∼50 cm below the earth's surface.

A study of backscattering mechanisms from a vegetative medium

Abstract The motivation of this present study is to investigate the relative contributions of the three major scattering interactions from a vegetative medium, namely the dif‐ fuse scattering contribution by the vegetation volume, the diffuse surface‐volume interactions and the direct surface scattering contribution. Such analysis allows us to study the conditions under which the total backscatter can be obtained by simple theoretical models that add incoherently the volume backscatter and the surface backscatter without taking the surface‐volume interactions into consideration. Electromagnetic backscattering from a vegetative medium is modelled based on the Monte Carlo technique. The vegetative model consists of two layers: the top layer contains a mixture of randomly‐oriented discrete disk‐shaped scatterers and cylindrically‐shaped scatterers, representing the leaves and stems of the vegetative canopy respectively; while the bottom layer is a semi‐infinite space representing the ground. The ground‐vegetation interface is characterized by a Kirchhoff rough surface based on the stationary‐phase approximation. Numerical illustrations of the relative contributions to the microwave backscatter cross‐sections from volume‐volume interactions, surface scattering and surface‐volume interactions at different frequencies are given. It is found that at high frequency (>6 GHz) and large incident angle (>50°), volume‐volume scattering process is the dominant scattering mechanism for backscatter. At low frequency and for near‐vertical incident angle, contribution to main‐polarized backscatter is dominated by direct surface scattering; while surface‐volume interaction is the major backscatter mechanism for cross‐polarized return. Thus, in general, the surface‐volume interaction should not be neglected for L‐ and C‐band range of frequency. Also illustrated are the effects on backscatter coefficients by volume fraction and moisture content of vegetative components; as well as effect of soil moisture content.

Failure mechanisms in loess and the effects of moisture content changes on remoulded strength

Investigations into the failure mechanisms of loess slopes in the loess region of north-central China have shown that a majority of mass movements are associated with shallow slab slides predominantly moving under tension. The effects of soil-moisture content are of paramount importance: when dry, vertical slopes in loess may exceed 15 m in height, but under conditions close to saturation the structural strength of loess rapidly decreases, causing failure of the slopes. Mass failure of loess occurs as collapse due to hydroconsolidation, and disintegration of the loess fabric as a result of liquefaction or fluidization, and can be associated with progressive failure processes. Local destruction of the openwork fabric of the loess can lead to small ‘plastic’ movements within the loess deposits. This is as close as loess can come to creep.

Pull and lift forces on multiple cage wheel lugs when operating in wet clay soil

The forces acting on multiple cage wheel lugs were measured when operating in wet clay soil. In a previous study, it was observed that the soil behaviour under the second and subsequent lugs was the same; therefore the forces under these lugs will be the same. Hence only two lugs were used in this study. The effects of soil moisture content, lug sinkage, slip and spacing on lug forces were studied. The lug normal and tangential reactions were measured with the help of strain gauged transducers. These forces were then converted to lug pull and lift forces. It was observed that lug forces on the preceding lug were always higher than those on the succeeding lug. For both the lugs, an increase in soil moisture content caused a decrease in lug forces, but an increase in lug sinkage caused an increase in lug forces. The lug slip did not affect the forces on the preceding lug, but it showed a significant effect on the forces on the succeeding lug. The lug spacing affected the forces on the succedding lug. The comparison of forces predicted by the conventional passive earth pressure theory and measured forces showed that the theory overestimated the lug forces for both lugs. The overestimation was higher for the succeeding lug forces than for the preceding lug forces.

Effect of Soil Moisture Content on Power Requirements

Effect of Soil Moisture Content on Power Requirements

THE EFFECT OF TEMPERATURE AND INITIAL SOIL MOISTURE CONENT ON THE VOLATILIZATION OF AMMONIA FROM SURFACE-APPLIED UREA

Through both laboratory and field experiments, we studied the effects of soil moisture content on ammonia (NH3) volatilization from urea, surface-applied to bare Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf). In the laboratory trial, urea fertilizer treatments were applied to cylindrical cores of soil in a flow-through apparatus. Volatilized NH3 was measured by passing humid air through the head space and into boric acid traps for 12 d. Total loss from urea on soil with 0.15 kg kg−1 moisture content was 30.7% and on soil with 0.22 kg kg−1 moisture content, 18.3%. Nitrogen-15-enriched urea was applied to the surface of soils at 0.15 and 0.22 kg kg−1 moisture content in confined cylindrical microplots in a field site in May and July 1985. Soil in the microplots dried during the 14-d trials, because the site was covered during periods of rainfall. Samples were analyzed 0, 3, 7, and 14 d after urea after urea application. The mean air temperature was 15.0°C in May and 20.5°C in July. After 14 d, 15N recovery from 0.22 kg kg−1 moisture soil was 71.9% in May and 60.0% in July. Recovery from 0.15 kg kg−1 moisture soil was 95.5% in May and 84.9% in July. We concluded that under drying conditions greater volatilization occurs in soil with a greater initial moisture content, but when soil moisture conditions remain essentially constant, as occurred in the laboratory experiment, there is less volatilization from the soil with the greater moisture content. Also, there are greater NH3 volatilization losses at higher temperatures, given adequate moisture to ensure complete and rapid urea hydrolysis.

The laboratory germination of crisp lettuce seeds under moisture stress

SUMMARYSeeds of the crisp lettuce cultivar Pennlake were germinated using all combinations of six ‘initial’ solutions of polyethylene glycol 6000 (PEG) with osmotic potentials ranging from 0 to ‐8 bars and seven ‘secondary’ solutions of PEG with osmotic potentials ranging from 0 to ‐10 bars, to which seeds were moved after 24 or 48 h in the ‘initial’ solution. The number of seeds germinating decreased at more negative osmotic potentials of both ‘initial’ and ‘secondary’ solutions but there was an interaction between germination temperature and the osmotic potential of the ‘initial’ solution. At an ‘initial’ solution osmotic potential of 0 bars germination at 20°C exceeded that at 10°C. As the osmotic potential of the ‘initial’ solution decreased germination at 20°C decreased more than at 10°C so that at the more negative osmotic potentials germination at 10°C exceeded that at 20°C. However seeds ungerminated after 14 days germinated normally when transferred back to water, so that the average final germination was 99.5%.The results suggest that major fluctuations in soil water potential in a seedbed are unlikely to influence seed germination per se provided that a period of 24 to 48 h at 0 bars tension is available at some time. The timing of such a period relative to sowing will have a considerable effect on the time of germination and hence the time of emergence. It is concluded that factors other than the direct effect of soil moisture content on germination are involved in reducing seedling emergence under fluctuating soil moisture conditions in the field.