Distribution of humic compounds in mounds of some soil-feeding termite species of tropical rainforests: its influence on soil structure stability

Summary A comparison was made of some physicochemical characteristics of epigeous termitaries (nest walls and surrounding horizons) of four species of soil-feeding termites living in tropical rainforests. Our aim was to determine whether these species affect the different compounds involved in the structural stability of soil in a similar manner.Our data support the general finding that the structural stability of soil is correlated with organic matter, cations and the relative proportion of mineral elements. Of these parameters, the content of organic matter is the most significant factor effecting the stability of termite building materials. Analysis of humic compound distribution revealed that fulvic and humic acids, owing to their electrochemical properties, are highly involved. Also, the organic matter in termitaries is more polymerized than that of humiferous control horizons, leading to FA/HA ratios close to 1.The stability of nest walls and topsoils differs between the species. Generally, the speciesNoditermes lamanianus, Thoracotermes macrothorax andCubitermes fungifaber build nests that are enriched with organic matter and exchangeable cations, resulting in high structural stability. In contrast, materials worked byCrenetermes albotarsalis are not enriched with organic matter or cations and do not differ in stability from the control soils.It is concluded that any generalization on the overall influence of soil-feeding termites on soil fertility might be misleading. Only species which enrich their materials with organic matter, especially stabilised humic acids, contribute to soil conservation and hence fertility. Once the termitary is dead, its organic matter is again available to the soil ecosystem.     

Effect of organic fertilisers on the greening quality, shoot and root growth, and shoot nutrient and alkaloid contents of turf-type endophytic tall fescue, Festuca arundinacea

Increasing concern about the potential negative environmental impact of chemical fertilisers used in urban landscapes has provided impetus to develop organic fertilisers. However, little is known about the effect of organic fertilisers on turfgrass quality, growth and stress resistance. This study compared the effect of 11 organic fertilisers, applied at manufacturer's recommended rates, on greening quality, shoot and root growth, and shoot nutrient (an indication of nutrient uptake) and alkaloid content (an indication of insect resistance) in endophytic (infected with the fungus Neotyphodium coenophialum) tall fescue in the greenhouse. We measured turfgrass greening quality on a 1–9 scale weekly (9 being the highest), shoot and root growth monthly, and shoot contents of macro- and micronutrients and of various alkaloids at the end of 4 months. The results show that Corn Gluten and Cockadoodle Doo produce the highest turfgrass greening quality and shoot growth. Nature's Touch with enzymes enhanced root growth, and thus resulted in high root:shoot ratio, especially in third and fourth months after application. Compared with the most commonly used chemical fertiliser, Scott's Turf Builder, the organic fertilisers Cockadoodle Doo, Corn Gluten and Nature's Touch with enzymes generally resulted in better turf greening quality. Although Cockadoodle Doo, Vigoro and Scott's Turf Builder resulted in higher macronutrient contents in turfgrass shoots, there was no significant correlation between the nutrient contents in the fertilisers and in the shoots four months after application. Significant differences were found for all measured alkaloids in turfgrass shoots among the 13 treatments, and these differences varied with fertiliser. Overall, organic fertilisers produced higher turfgrass greening quality, root and shoot growth and insect resistance capacity (alkaloid content) compared with the chemical fertiliser, Scott's Turf Builder. On the basis of the high to excellent turfgrass greening quality ratings, root:shoot ratio, shoot nutrient and alkaloid contents in this study, we conclude that Cockadoodle Doo, Vigoro and Nature's Touch with enzymes are relatively superior organic fertilisers.     

Organic acids and prolonged nitrogenase activity by non-growing,free-living Rhizobium japonicum

Rhizobium japonicum 61-A-101 grew and fixed nitrogen more effectively on media containing an organic acid and a pentose sugar than on media containing only one of these carbon sources. Peak specific activities in the range 10–15 nmol C₂H₄ · h^-1 · mg protein^-1 were found for these organisms in a spot of growth about 1 cm diameter on agar surfaces exposed to air. Increasing concentrations of the organic acids (succinate or malonate) in a medium containing arabinose resulted in longer lasting activity. The inclusion of a third carbon source, glycerol, gave activity which remained at the maximum from about the 8 to the 18 day after inoculation although no growth of the bacteria occurs during the last 8 or 10 days. At low concentration of organic acid l-arabinose was a much better carbon source for supporting nitrogenase activity of these organisms that the d-form. Both organic acids affected the morphology of the bacteria. Higher concentrations, especially of malonate, gave swollen and distorted cells. When bacteria growing on organic acid-containing agar plates were suspended and plated after appropriate dilution on yeast extract — mannitolglycerol agar there was heterogeneity of colony form, with up to 90% microcolonies after growth on high malonate concentrations. The effects of malonate may be correlated with characteristics of the bacteroid form inside the nodule which contains relatively high concentrations of organic acids, especially malonate.     

Palaeolimnology of Neusiedlersee,Austria

Eighteen sediment cores from the Neusiedlersee reed belt were analysed for organic and inorganic carbon, nitrogen, organic and inorganic phosphorus and trace metal content. The depth variation of the distribution patterns of C, P and N in the cores are influenced by: 1. temporal variability of organic matter deposition (e.g. burial of Phragmites litter) 2. the impact of a number of astatic phases in the history of the lake, and 3. early palaeo-ecological changes associated with the alteration of marine to lacustrine environment. At some sites, due to mineralisation, the organic phosphorus compartment in the Pannonian sediments is completely exhausted; accordingly there is a parallel decrease in carbon and nitrogen content in the profiles. These changes in the pattern of the distribution of the nutrients (especially organic phosphorus) can be used to differentiate between the recent and the upper boundary layer of the tertiary sediments. There is no clear trace metal distribution pattern observed in the cores but the Pannonian sediments recorded the lowest levels. In contrast, at some locations surface sediments register a two to three fold increase. The highest C, P, N, values and trace metal concentrations are recorded in the surface sediments deposited after the drying up of the lake a hundred and twenty-two years ago.     

Soil solution chemistry in lodgepole pine (Pinus contorta ssp. latifolia) ecosystems,southeastern Wyoming,USA

Concentrations of the principal inorganic and organic solutes in the soil root-zone were measured in six contrasting lodgepole pine (Pinus contorta ssp.latifolia) forest ecosystems for five years (1979–1983). Consistent temporal changes in the principal inorganic solutes (Ca, Mg, K, Na, SO₄, Cl) were observed in all the forest stands and years of study: high concentrations at the initiation of snowmelt in the spring were followed by rapid declines to rather constant values in the mid to late stages of snowmelt. Except for K, concentrations of these solutes differed significantly between sites and between years. Sulfate was the principal mobile anion in the root-zone soil solutions, but contributions of bicarbonate and organic anions also were important.The pH of root-zone solutions was relatively high (6.0), did not change significantly as snowmelt proceeded, and was significantly lower in high-clay soils. No consistent trends in bicarbonate alkalinity were observed and soil atmosphere CO₂ concentrations were only about 10 to 20 times above atmospheric levels, peaking at the end of the snowmelt interval. Concurrent changes in the concentrations of dissolved organic carbon, non-volatile acid-neutralizing capacity, and total Al and Fe indicated that these soil-forming metals were transported vertically in the soil as organic complexes. Precipitation of these complexes was more rapid and more complete in the soils with high clay content than in the coarser soils. Moreover, organic anions comprised up to 30% of the total anionic charge in the coarse-textured soils but less than 10% in the fine soils.Little seasonal or spatial variation of inorganic N and P concentrations was observed in root-zone solutions, probably as a result of high biotic demand for these limiting nutrients. Flux of N and P in these ecosystems was predominately via organic forms so that losses of these nutrients was strongly linked to the mobility of dissolved organic carbon. However, a two-fold increase in the organic N:P and C:P ratios was observed during passage of melt water from the forest floor to mineral soil, evidence of more rapid mineralization of organic P.     

Recent sedimentological conditions in the delta of the river Kyrönjoki,Western Finland

The estuary of the River Kyrönjoki was echo sounded and, on the basis of these results the delta was delimited and areas of erosion and accumulation were separated. Samples of the sediment surface (0–2 cm) from 65 sites in the estuary were analysed for organic content, C, N, P, Ca, Fe, Mn, Pb, Cu, Zn, Cd and Hg. On the basis of the chemical analyses the delta was divided into two parts according to the sedimentary conditions: (I) In the inner part, where acid fresh water of c. pH 5.5 from the river is predominant, the conditions were reducing. The Fe/Mn ratio of the sediment was high. The heavy metal content was usually low. The Hg content in the organic compounds of the sediment was, due to the acidity, higher than in the outer part. (II) In the outer part of the delta, where neutral brackish water of pH c. 7.0 dominates, the sedimentary conditions were mostly oxidizing. The Fe/Mn ratio was very low. The heavy metal and organic content was mostly high in the accumulation areas. This is because the fine-grained allochthonous material, which has a high heavy metal and organic content, flocculates and precipitates when it reaches the brackish water of the Gulf of Bothnia, and the salinity and the pH are higher.     

Zur Kinetik der Nebenproduktbildung bei der Überproduktion von Citronensäure durch Saccharomycopsis lipolytica

After exhaustion of the N-sources the yeast S.l. excretes citric and isocitric acid with high rates without interferring in the postlogarithmic phase the intracellular production of reserve materials like polysaccharides and especially lipids. The synthesis of citric acids and of reserve materials are therefore autonomically proceeding processes inside of the cells With increasing lipid content the ergosterol content increases The utilization of the ergosterol rich yeasts as valuable byproduct of the citric acid production is discussed.     

Physiological response of Spisula subtruncata (da Costa, 1778) to different seston quantity and quality

Individuals of the bivalve Spisula subtruncata were fed a mixed diet comprising of sea water enriched with the diatom Phaeodactylum tricornutum and ashed silt within a range of concentrations, simulating natural conditions above pseudofaeces threshold. The designed ranges for total particulate matter were between 10 and 30 mg l^–1and organic content of seston 15–40%. Filtration rate, rejection rate, ingestion rate and absorption rate were measured at those different conditions. Filtration rate and rejection rate were significantly correlated to total particulate matter and percentage of organic matter, with higher rates at higher values of total particulate matter and lower values of percentage organic matter. Ingestion rate was maintained at similar levels in all the treatments and organic enrichment of the ingested food occurred due to preingestive selection of the filtered material. A differential absorption rate occurred at different levels of organic matter in the diet with high rates at high values of the organic content of the diet. S. subtruncata showed different physiological responses to changes of the food conditions: (1) Increase of pseudofaeces production at increasing levels of particulate matter, (2) preingestive selection of organic material which enriched the organic fraction of ingested food, (3) stabilized ingestion rate and (4) increase of the absorption rate at high organic levels of the seston.     

Sources of organic nitrogen,phosphorus and carbon in antarctic streams

Dissolved and particulate organic materials were analysed in 14 streamwaters of the McMurdo Sound region of Antarctica. These streams are fed by glacial meltwaters and pass through catchments largely devoid of terrestrial vegetation. Nonetheless they contained measurable amounts of organic material in both dissolved and particulate form. Most of the dissolved organic carbon (DOC) values lay in the range 1–3 g C m^–3. Higher values were recorded close to penguin rookeries on the coast. Dissolved organic nitrogen (DON) concentrations were generally two orders of magnitude less than DOC and in flowing waters with rich blue-green algal growth DON increased with distance downstream. Dissolved organic phosphorus levels were generally much lower than DON, but highly variable. Particulate organic carbon concentrations (both fine and coarse) were unexpectedly high. Five sources of organic matter were identified: birdlife (only near the coast), autochthonous algal production (especially important for DON), streambed soils (important at first flows), lacustrine and marine sediments, through which certain streams and glaciers cut, and the glacial ice, which received organic input from wind-blown particulates, snowfall and the underlying bedrock of sedimentary origin. Highest organic levels were recorded in the first melt down the glacier face, suggesting that winter deposition of organic materials may be especially important.     

Tube-building in two epifaunal amphipod species,Corophium insidiosum andJassa falcata

Jassa falcata andCorophium insidiosum are epifaunal tube-building marine amphipods, whose niches overlap in habitat and food requirements. Laboratory experiments were conducted to study the influence of the quality of different available particulate substrates on settlement and tube-building behaviour of these two amphipod species. Our experiments suggest thatC. insidiosum is less specialized in this respect thanJ. falcata. C. insidiosum is able to use organic materials for tube-building such as artificial (Ulva spec. powder) or mixed natural detritus as well as inorganic material (coarse sand); whereasJ. falcata utilizes organic materials, but sand only to a very limited extent.     

Importance of nutrients,organic matter and light availability on epilimnetic metabolic rates in a mesotrophic tropical lake

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Effect of the hydration state of supports before lyophilization on subtilisin-A activity in organic media

Subtilisin-A was colyophilized with various types of support materials, such as Amberlite IRC-50, Celite545, chitosan, DEAE-cellulose, DOWEX-1, zeolite, glass bead, and polystyrene. The colyophilized enzyme was used for the optical resolution of racemic 1-phenylethylamine with 2,2,2-trifluoroethylbutyrate in 3-methyl-3-pentanol. The enzyme activity in organic media changed dramatically according to the hydration state of the support materials before lyophilization. This effect was especially marked with supports of high water capacity (aquaphilicity), such as chitosan and DEAE-cellulose. By hydrating these supports of high aquaphilicity prior to lyophilization, subtilisin-A activity in organic media increased ca. 4-8 times, depending upon the supports used. This result suggests that the hydration state of aquaphilic support materials for colyophilization is critical to determining enzyme activity in organic solvents. (c) 1996 John Wiley & Sons, Inc.     

Portulacaria afra is constrained under extreme soil conditions in the Fish River Reserve, Eastern Cape, South Africa

Restoration of degraded thicket landscapes can be achieved by planting Portulacaria afra (spekboom) cuttings. The factors determining P. afra abundance in thicket types not dominated by P. afra are of interest to restoration practitioners because they could influence restoration protocols using P. afra cuttings in these landscapes. We consequently investigated the relationship between P. afra cover and soil properties, namely pH, EC, organic C, particle size distribution and total content of 26 elements at 78 sites in the Fish River Reserve, Eastern Cape province, South Africa. P. afra cover showed a consistent pattern of constraint at extreme levels (both high and low) of subsoil EC, organic C, sand content, Ca, Zn and Al. The results suggest that P. afra is most competitive in intermediate edaphic environments in the Fish River Reserve. It remains to be investigated in restored landscapes whether P. afra cutting survivorship and growth are greater in such soils.     

Development of Dopant‐Free Organic Hole Transporting Materials for Perovskite Solar Cells

There has been considerable progress over the last decade in development of the perovskite solar cells (PSCs), with reported performances now surpassing 25.2% power conversion efficiency. Both long‐term stability and component costs of PSCs remain to be addressed by the research community, using hole transporting materials (HTMs) such as 2,2′,7,7′‐tetrakis(N,N′‐di‐pmethoxyphenylamino)‐9,9′‐spirbiuorene(Spiro‐OMeTAD) and poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA). HTMs are essential for high‐performance PSC devices. Although effective, these materials require a relatively high degree of doping with additives to improve charge mobility and interlayer/substrate compatibility, introducing doping‐induced stability issues with these HTMs, and further, additional costs and experimental complexity associated with using these doped materials. This article reviews dopant‐free organic HTMs for PSCs, outlining reports of structures with promising properties toward achieving low‐cost, effective, and scalable materials for devices with long‐term stability. It summarizes recent literature reports on non‐doped, alternative, and more stable HTMs used in PSCs as essential components for high‐efficiency cells, categorizing HTMs as reported for different PSC architectures in addition to use of dopant‐free small molecular and polymeric HTMs. Finally, an outlook and critical assessment of dopant‐free organic HTMs toward commercial application and insight into the development of stable PSC devices is provided.     

改变施肥管理后不同肥力稻田土壤CO2排放特征

利用一个长达30a水稻土长期定位试验,在保证原有定位试验继续正常开展的前提下,将原化肥处理改施有机肥,原有机肥处理改施化肥或者增施有机肥。通过观测田间试验2012—2013年双季稻轮作周期内不同肥力水平稻田土壤施肥管理改变后的土体CO2排放通量(FCO2),研究不同后续施肥管理对不同肥力红壤性水稻土CO2排放的影响。结果表明:变更施肥能明显改变CO2排放动态变化,其中长期施用有机肥处理改施化肥后其FCO2明显减小,长期施用化肥或有机肥处理增施有机肥后其FCO2显著增大。有机肥和土壤有机碳均可促进土体CO2排放,有机肥处理有机物料碳添加量与CO2-C年排放量呈极显著的正相关关系(r=0.9015**,n=21),单施化肥处理土壤有机碳含量与土体CO2-C年排放量符合线性方程:y=10.962x-68.86(R2=0.7507,n=9,P0.01)。长期施用有机肥土壤改施化肥会导致其有机碳矿化损失,土壤有机碳含量越高,矿化损失量越多,最终其有机碳水平将与长期施用化肥的土壤有机碳平衡值一致;长期施用化肥或有机肥土壤改施或增施有机肥可促进土壤有机碳积累,外源添加碳越多,土壤积累碳越多;相同有机肥施用量下土壤有机碳含量越高,有机物料表观分解率越大,积累于土壤中的有机碳越少,不同有机碳水平土壤在相同有机肥管理下其有机碳最终会达到相同的平衡值。在有机碳水平较低(20.46 g/kg)红壤稻田上增施有机肥是提升已培肥水稻土有机碳含量的可持续发展措施,而在有机碳水平较高(14.45 g/kg)红壤稻田上应避免改施化肥。总之,在有机碳含量较高或者较低的中国南方红壤性水稻土上,持续的有机肥施用是保持或者提高其有机碳水平的必要措施。     

Tissue-specific organic acid metabolism in reproductive and non-reproductive parts of the fig fruit is partially induced by pollination

Organic acids are important components of overall fruit quality through flavor, taste, nutritional and medicinal values. Pollinated fig (Ficus carica L.) fruit quality is enhanced by increased acidity. We quantified the major organic acids and characterized the expression pattern of organic acid metabolic pathway-related genes in the reproductive part – inflorescence and non-reproductive part – receptacle of parthenocarpic and pollinated fig fruit during ripening. Essentially, pollinated fruit contains seeds in the inflorescence, as opposed to no seeds in the parthenocarpic inflorescence. The major organic acids – citrate and malate – were found in relatively high quantities in the inflorescence compared to the receptacle of both parthenocarpic and pollinated fig fruit. Notably, pollination increased citric acid content significantly in both inflorescence and receptacle. Genes related to the phosphoenolpyruvate carboxylase (PEPC) cycle, tricarboxylic acid cycle, citrate catabolism and glyoxylate cycle were identified in fig fruit. Expression levels of most of these genes were higher in inflorescences than in receptacles. In particular, FcPEPC and FcFUM (encoding fumarase) had significantly higher expression in the inflorescence of pollinated fruit. Most importantly, expression of the glyoxylate cycle genes FcMLS and FcICL (encoding malate synthase and isocitrate lyase, respectively) was induced to strikingly high levels in the inflorescence by pollination, and their expression level was highly positively correlated with the contents of all organic acids. Therefore, the glyoxylate cycle may be responsible for altering the accumulation of organic acids to upgrade the fruit taste during ripening, especially in the pollinated, seeded inflorescence.     

Effects of European Earthworm Invasion on Soil Characteristics in Northern Hardwood Forests of Minnesota, USA

European earthworms are colonizing worm-free hardwood forests across North America. Leading edges of earthworm invasion in forests of northern Minnesota provide a rare opportunity to document changes in soil characteristics as earthworm invasions are occurring. Across leading edges of earthworm invasion in four northern hardwood stands, increasing total earthworm biomass was associated with rapid disappearance of the O horizon. Concurrently, the thickness, bulk density and total soil organic matter content of the A horizon increased, and it’s percent organic matter and fine root density decreased. Different earthworm species assemblages influenced the magnitude and type of change in these soil parameters. Soil N and P availability were lower in plots with high earthworm biomass compared to plots with low worm biomass. Decreases in soil nitrogen availability associated with high earthworm biomass were reflected in decreased foliar nitrogen content for Carex pensylvanica, Acer saccharum and Asarum canadense but increased foliar N for Athyrium felix-femina. Overall, high earthworm biomass resulted in increased foliar carbon to nitrogen ratios. The effects of earthworm species assemblages on forest soil properties are related to their feeding and burrowing habits in addition to effects related to total biomass. The potential for large ecosystem consequences following exotic earthworm invasion has only recently been recognized by forest ecologists. In the face of rapid change and multiple pressures on native forest ecosystems, the impacts of earthworm invasion on forest soil structure and function must be considered.     

The influence of organic fertilizers,obtained from poplar barks,on the correction of iron chlorosis ofLupinus albus L.

Summary The influence exerted by organic matter on the correction of iron chlorosis inLupinus albus L., grown in calcareous soil, was studied through a pot experiment by incorporating two rates (1.5 per cent and 3 per cent on the soil) of three organic fertilizers obtained from poplar barks. The fertilizers differed in the length of humification process and in the integration with different materials,i.e.: H fertilizer: 8 months humified poplar barks without any addition, HF fertilizer: 4 years humified poplar barks with 4 per cent of metallic iron, HP fertilizer: 18 months humified poplar barks with 25 per cent of poultry manure. The higher rate (3 per cent) of the H fertilizer was the most efficient in reducing chlorosis symptoms and gave the greatest dry matter yield. Among the treatments with the lower rate (1.5 per cent), the HF fertilizer gave the best results; conversely, the HP fertilizer failed to correct chlorosis and to enhance yield. Therefore the experiment suggested that organic fertilizers are useful to correct iron chlorosis, provided their phosphorus content is low and they have undergone a prolonged humification process; furthermore, integration with small amounts of iron leads to a considerable saving of organic fertilizer.     

Organic matter and soil biota of upland wetlands in Taylor Valley,Antarctica

In January 2001, we surveyed streams and ponds above 300 m a.s.l. in Taylor Valley, South Victoria Land, Antarctica. One pond was examined in detail. Organic materials covered nearly 100% of the adjacent soil to 5–20 m from the shore, with intermittent patches to 80 m. Organic matter averaged 257 g C/m², and totaled 1,388 kg organic C on the soil around the pond. Soil-moisture content (0.56–12.41%) decreased with distance from shore, whereas pH (7.8–10.8) increased with distance. Electrical conductivity was lowest in the soils <10 m from the pond (416±94 µS/cm). Mineral soil organic C and total N concentrations were greatest between 10 and 30 m from the edge of the pond (1.21±0.37 and 0.13±0.05 mg/g soil, respectively). Soil invertebrates were present in only 50% of samples and included tardigrades, rotifers, and two nematodes, Scottnema lindsayae and Plectus antarcticus. A non-parametric, discriminant function analysis based on soil moisture, soil organic carbon, and electrical conductivity correctly predicted 87.0% of sites that had invertebrates and 70.8% of sites for which invertebrates were absent. Tardigrades, rotifers, and P. antarcticus were found only in the wettest soils nearest the pond whereas S. lindsayae was restricted to drier soils further from shore. Other ponds and streams also showed substantial accumulations of organic matter, suggesting that upland wetlands serve as resource islands in these polar deserts that provide a source of organic matter to nearby soils.     

Factors affecting the occurrence and distribution of entomopathogenic fungi in natural and cultivated soils

Factors affecting the occurrence and distribution of entomopathogenic fungi in 244 soil samples collected from natural and cultivated areas in Spain were studied using an integrated approach based on univariate and multivariate analyses. Entomopathogenic fungi were isolated from 175 of the 244 (71.7 %) soil samples, with only two species found, Beauveria bassiana and Metarhizium anisopliae. Of the 244 soil samples, 104 yielded B. bassiana (42.6 %), 18 yielded M. anisopliae (7.3 %), and 53 soil samples (21.7 %) harboured both fungi. Log-linear models indicated no significant effect of habitat on the occurrence of B. bassiana, but a strong association between M. anisopliae and soils from cultivated habitats, particularly field crops. Also, irrespective of habitat type, B. bassiana predominated over M. anisopliae in soils with a higher clay content, higher pH, and lower organic matter content. Logistic regression analyses showed that pH and clay content were predictive variables for the occurrence of B. bassiana, whereas organic matter content was the predictive variable for M. anisopliae. Also, latitude and longitude predicted the occurrence of these same species, but in opposite directions. Altitude was found to be predictive for the occurrence of B. bassiana. Using principal component analysis, four factors (1 to 4) accounted for 86 % of the total variance; 32.8, 22.9, 19.6 and 10.4 % of the cumulative variance explained, respectively. Factor 1 was associated with high positive weights for soil clay and silt content and high negative weights for soil sand content. Factor 2 was associated with high positive weights for soil organic matter content and high negative weights for soil pH. Factor 3 was associated with high positive weights for latitude and longitude of the sampled localities and factor 4, had high positive weights only for the altitude. Bi-plot displays representing soil samples were developed for different factor combinations and indicated that, irrespective of geographical location, absence of both fungal species was determined by alkaline sandy soils with low organic matter content, whereas heaviness of soil texture, acidity and increasing organic matter content led to progressively higher percentages of samples harbouring entomopathogenic fungi. These results could aid decision-making as to whether or not a particular cultivated or natural soil is suitable for using entomopathogenic fungi as a pest control measure and for selecting the fungal species best suited to a particular soil.