Managing soils to enhance the potential for bioremediation of water repellency

Soil Research ◽  
2005 ◽  
Vol 43 (7) ◽  
pp. 803 ◽  
Author(s):  
Margaret M. Roper
Keyword(s):  
Management Practices ◽  
Crop Yields ◽  
Water Repellency ◽  
Water Infiltration ◽  
Most Probable Number ◽  
Water Repellent ◽  
Gradual Decline ◽  
Kaolinite Clay ◽  
Probable Number ◽  
Degrading Bacteria

Water repellency can significantly reduce crop and pasture establishment and production in sandy soils. Management practices that increase the rate of water infiltration into dry soils following the first rains at the end of the dry season were investigated. In the laboratory, addition of water to water repellent soil and maintenance of warm moist conditions produced a gradual decline in water repellency. This was supported by results in the field which showed that under daily irrigation there was a gradual decline in water repellency over time. However, under dryland conditions, other mechanisms to increase water infiltration had to be found. In the laboratory, after the addition of lime and kaolinite clay, there was an initial rapid decline in repellency, indicative of a physical mechanism, followed by a more gradual decline suggesting a biological response. In the field, under dryland conditions, the addition of lime and kaolinite clay resulted in a reduction in water repellency, and in the case of lime, this effect increased with the size of application. Estimates of the numbers of wax-degrading bacteria in the treated soils, using a most-probable-number assay, showed at least a 10-fold increase in lime-treated sands, but not in the clay-treated sands. The results suggest that lime may provide a viable alternative for increasing the wettability of soils by physical mechanisms and by promoting microbial activity by bacteria responsible for wax degradation, resulting in more consistent plant germination and establishment, and increased crop yields.

Enumeration of wax-degrading microorganisms in water repellent soils using a miniaturised Most-Probable-Number method

Soil Research ◽  
2005 ◽  
Vol 43 (2) ◽  
pp. 171 ◽  
Author(s):  
Margaret M. Roper ◽  
V. V. S. R. Gupta
Keyword(s):  
Agricultural Soils ◽  
Carbon Sources ◽  
Coconut Oil ◽  
Water Repellency ◽  
Most Probable Number ◽  
Water Repellent ◽  
Natural Habitats ◽  
Probable Number ◽  
Degrading Bacteria ◽  
Pure Cultures

The ability of a soil to reduce waxes that cause water repellency depends, in part, on the presence of populations of wax-degrading microorganisms. Therefore, estimating the size of populations of wax-degrading bacteria in water repellent soils is likely to be a useful indicator of the potential for bioremediation of water repellency. A Most Probable Number (MPN) method that selects specifically for the function of wax degradation in bacteria was developed and tested using both pure cultures and natural populations of wax-degrading bacteria. Two carbon sources (coconut oil and hexadecane) that contain fatty acids or hydrocarbons implicated as causative agents of water repellency were compared in terms of growth and emulsification by a range of known wax-degrading bacteria. Emulsification resulting from surfactant production, a direct measure of wax degradation, was the criterion for a positive test. All the bacteria tested emulsified coconut oil, which was chosen as the carbon source in subsequent testing of the MPN assay. Population estimates of pure cultures of wax-degrading bacteria (liquid suspensions and inoculated into sterile soils) made using the MPN and a plating technique showed good agreement between the 2 methods, indicating that the MPN method gives an accurate measure of size of the wax-degrading population. Extensive replication of MPN counts of known wax-degrading bacteria inoculated into sterile soils or populations in soils collected from a range of natural habitats showed little variation within samples, indicating that the new method was reproducible. Based on its accuracy and reproducibility the MPN method was deemed suitable for estimating populations in a range of soils. Monitoring wax-degrading populations under different agricultural managements and at different times of the year, i.e. seasonal dynamics, could provide clues for the development of new managements that minimise the risk of water repellency in agricultural soils.

Potential for remediation of water repellent soils by inoculation with wax-degrading bacteria in south-western Australia

Biologia ◽  
2006 ◽  
Vol 61 (19) ◽  
Author(s):  
Margaret Roper
Keyword(s):  
Water Repellency ◽  
Water Infiltration ◽  
Small Scale ◽  
Water Repellent ◽  
Degrading Bacteria ◽  
Soil Conditioners ◽  
Scale Experiment ◽  
Increased Activity ◽  
Reduced Water ◽  
Rhodococcus Sp

AbstractWater repellency resulting from waxy coatings around soil particles causes significant crop and pasture losses. Bioremediation of these soils using inoculation of wax-degrading bacteria was investigated under field conditions. In a small scale experiment without any additional nutrients or soil conditioners, 2 inoculants (Rhodococcus sp. and Roseomonas sp.) out of 7 resulted in significant improvements in water infiltration. A larger scale experiment had compost and fertiliser applied to support inoculants in nutrient-poor sands and lime was added to half the treatments. There were 6 different inoculants and their mixtures. One inoculant (Mycobacterium sp.) significantly reduced water repellency on its own. However, the addition of lime produced a significant “inoculant by lime” interaction, and limed treatments with each of the 5 individual cultures of Rhodococcus spp. and a mixture containing the 5 cultures of Rhodococcus spp. and 1 culture of Mycobacterium sp. all resulted in significant reductions in water repellency when compared with their non-limed counterparts and controls. Lime alone (1 t/ha, 70% neutralising value) produced a small but significant benefit compared with the non-limed control. The results indicate that there is potential to increase soil wettability through increased activity by wax-degrading bacteria.

scholarly journals Effects of Monoculture, Crop Rotation, and Soil Moisture Content on Selected Soil Physicochemical and Microbial Parameters in Wheat Fields

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
A. Marais ◽  
M. Hardy ◽  
M. Booyse ◽  
A. Botha
Keyword(s):  
Soil Moisture ◽  
Microbial Communities ◽  
Crop Rotation ◽  
Management Practices ◽  
Agricultural Soils ◽  
Soil Microbial Communities ◽  
Soil Microbial Activity ◽  
Most Probable Number ◽  
Probable Number ◽  
Soil Microbial

Different plants are known to have different soil microbial communities associated with them. Agricultural management practices such as fertiliser and pesticide addition, crop rotation, and grazing animals can lead to different microbial communities in the associated agricultural soils. Soil dilution plates, most-probable-number (MPN), community level physiological profiling (CLPP), and buried slide technique as well as some measured soil physicochemical parameters were used to determine changes during the growing season in the ecosystem profile in wheat fields subjected to wheat monoculture or wheat in annual rotation with medic/clover pasture. Statistical analyses showed that soil moisture had an over-riding effect on seasonal fluctuations in soil physicochemical and microbial populations. While within season soil microbial activity could be differentiated between wheat fields under rotational and monoculture management, these differences were not significant.

scholarly journals Water repellency of clay, sand and organic soils in Finland

2008 ◽  
Vol 16 (3) ◽  
pp. 267 ◽  
Author(s):  
K. RASA ◽  
R. HORN ◽  
M. RÄTY
Keyword(s):  
Preferential Flow ◽  
Management Practice ◽  
Soil Surface ◽  
Water Repellency ◽  
Organic Soil ◽  
Water Infiltration ◽  
Organic Soils ◽  
Water Repellent ◽  
Moisture Regime ◽  
Wetting Process

Water repellency (WR) delays soil wetting process, increases preferential flow and may give rise to surface runoff and consequent erosion. WR is commonly recognized in the soils of warm and temperate climates. To explore the occurrence of WR in soils in Finland, soil R index was studied on 12 sites of different soil types. The effects of soil management practice, vegetation age, soil moisture and drying temperature on WR were studied by a mini-infiltrometer with samples from depths of 0-5 and 5-10 cm. All studied sites exhibited WR (R index >1.95) at the time of sampling. WR increased as follows: sand (R = 1.8-5.0) < clay (R = 2.4-10.3) < organic (R = 7.9-undefined). At clay and sand, WR was generally higher at the soil surface and at the older sites (14 yr.), where organic matter is accumulated. Below 41 vol. % water content these mineral soils were water repellent whereas organic soil exhibited WR even at saturation. These results show that soil WR also reduces water infiltration at the prevalent field moisture regime in the soils of boreal climate. The ageing of vegetation increases WR and on the other hand, cultivation reduces or hinders the development of WR.;

Selective enumeration of aromatic and aliphatic hydrocarbon degrading bacteria by a most-probable-number procedure

1996 ◽  
Vol 42 (3) ◽  
pp. 252-258 ◽  
Author(s):  
Brian A. Wrenn ◽  
Albert D. Venosa
Keyword(s):  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Oxidation Products ◽  
Most Probable Number ◽  
Probable Number ◽  
Microtiter Plates ◽  
Degrading Bacteria ◽  
Polycyclic Aromatic ◽  
Pure Cultures ◽  
Plate Counts

A most-probable-number (MPN) procedure was developed to separately enumerate aliphatic and aromatic hydrocarbon degrading bacteria, because most of the currently available methods are unable to distinguish between these two groups. Separate 96-well microtiter plates are used to estimate the sizes of these two populations. The alkane-degrader MPN method uses hexadecane as the selective growth substrate and positive wells are detected by reduction of iodonitrotetrazolium violet, which is added after incubation for 2 weeks at 20 °C. Polycyclic aromatic hydrocarbon degraders are grown on a mixture of phenanthrene, anthracene, fluorene, and dibenzothiophene in a second plate. Positive wells turn yellow to greenish-brown from accumulation of the partial oxidation products of the aromatic substrates and they can be scored after a 3-week incubation period. These MPN procedures are accurate and selective. For pure cultures, heterotrophic plate counts on a nonselective medium and the appropriate MPN procedure provide similar estimates of the population density. Bacteria that cannot grow on the selective substrates do not produce false positive responses even when the inoculum density is very high. Thus, this method, which is simple enough for use in the field, provides reliable estimates for the density and composition of hydrocarbon-degrading microbial populations.Key words: most probable number, polycyclic aromatic hydrocarbon, alkane, hydrocarbon, bacteria.

THE FATE OF SALMONELLA TYPHIMURIUM IN THE MANUFACTURE AND RIPENING OF LOW-ACID CHEDDAR CHEESE1

1970 ◽  
Vol 33 (7) ◽  
pp. 280-284 ◽  
Author(s):  
H. S. Park ◽  
E. H. Marth ◽  
J. M. Goepfert ◽  
N. F. Olson
Keyword(s):  
Salmonella Typhimurium ◽  
Starter Culture ◽  
Most Probable Number ◽  
Initial Increase ◽  
High Moisture ◽  
Gradual Decline ◽  
Probable Number ◽  
Streptococcus Lactis ◽  
Extended Survival ◽  
Made In

Cheddar cheese was made by the stirred-curd procedure from pasteurized milk inoculated with Salmonellea typhimurium and with a slow acid-producing strain of Streptococcus lactis. The Most Probable Number technique was used to enumerate salmonellae in milk and in cheese during its manufacture and ripening. Salmonellae grew rapidly during manufacture and limited additional growth occurred in cheese during the first week of ripening at 13 C after which there was a gradual decline in population. Salmonellae survived during ripening for up to approximately 7 months at 13 C and 10 months at 7 C. Cheese made in 2 of 5 trials exhibited a limited increase in number of salmonellae during the first 2 weeks at 7 C followed by a decline in population of these bacteria. Other cheeses held at 7 C exhibited a reduction in number of viable salmonellae without the initial increase. Growth of salmonellae during the early stages of ripening and subsequent extended survival of these organisms may, in part, be attributable to high moisture (average 43.2%) and high pH (5.75 after overnight pressing) of the cheese which resulted from use of a slow acid-producing starter culture.

Impact of crop residue retention and tillage on water infiltration into a water-repellent soil

Biologia ◽  
2015 ◽  
Vol 70 (11) ◽  
Author(s):  
Philip R. Ward ◽  
Margaret M. Roper ◽  
Ramona Jongepier ◽  
Shayne F. Micin
Keyword(s):  
Crop Residue ◽  
Water Repellency ◽  
Water Infiltration ◽  
Soil Tillage ◽  
Water Repellent ◽  
Residue Removal ◽  
Growing Seasons ◽  
Water Repellence ◽  
The Impact ◽  
Residue Retention

AbstractWater repellence is a condition in which soils become hydrophobic and do not readily absorb water. The condition causes problems in agricultural production relating to water availability for seed germination and plant growth. In this research we assess the impact of disturbing the soil by a single annual soil tillage (compared with no-till) and crop residue retention (compared with residue removal by burning) on the severity of water repellency, and on water infiltration during and immediately after rainfall, for 5 discrete rainfall events over an 18-month period covering two crop growing seasons. Soil tillage and crop residue removal were associated with decreased severity of water repellency. Despite this, soil tillage resulted in less infiltration of rain water, especially in the crop inter-row spaces, one hour after the commencement of rainfall, and 6 hours after the conclusion of rainfall. Where a single soil tillage was performed, soil in the inter-row spaces absorbed 19-30% of incident rainfall, compared with 58-78% in undisturbed soils. This was observed for a rainfall event 11 months after soil tillage, indicating that soil tillage has a long-lasting impact on pathways of water entry into the soil.

The isolation and characterisation of bacteria with the potential to degrade waxes that cause water repellency in sandy soils

Soil Research ◽  
2004 ◽  
Vol 42 (4) ◽  
pp. 427 ◽  
Author(s):  
Margaret M. Roper
Keyword(s):  
Agricultural Production ◽  
Complex Mixture ◽  
Sandy Soils ◽  
Water Repellency ◽  
Water Repellent ◽  
Bacterial Isolates ◽  
Hydrophobic Compounds ◽  
Degrading Bacteria ◽  
Wide Range ◽  
Fatty Acids And Alcohols

Water repellency in soils is caused by waxy coatings on particles and can seriously limit agricultural production. Bioremediation of these soils, using wax-degrading bacteria isolated from soils and other sources rich in microorganisms, was investigated. Wool wax, a complex mixture of fatty acids and alcohols, was used to select bacteria capable of metabolising hydrophobic compounds. Of the 37 stable isolates, two-thirds were actinomycetes. These organisms are known for their ability to metabolise a wide range of organic compounds. Degradation of waxes associated with soil particles is facilitated by the production of biosurfactants that emulsify hydrophobic compounds. Measurement of biosurfactant production indicated that those isolates that grew best on hydrocarbon were also the most prolific biosurfactant producers. Inoculation of water-repellent soils, under controlled conditions, with the most efficient wax-degrading bacterial isolates resulted in significant improvements in soil wettability.

scholarly journals Management practices and honey characteristics of Melipona eburnea in the Peruvian Amazon

2020 ◽  
Vol 50 (12) ◽  
Author(s):  
Cesar Delgado ◽  
Kember Mejía ◽  
Claus Rasmussen
Keyword(s):  
Management Practices ◽  
Physicochemical Characteristics ◽  
Most Probable Number ◽  
Human Consumption ◽  
Peruvian Amazon ◽  
Probable Number ◽  
Honey Production ◽  
Microbiological Characteristics ◽  
Two Factors ◽  
Microbiological Analyses

ABSTRACT: Meliponiculture and associated honey production are activities with a great potential for general use and commercialization in the Peruvian Amazon. Lack of management techniques and limited knowledge of honey quality are two factors which may hinder the implementation of meliponiculture. The present study was conducted in three communities in the Peruvian Amazon where the production and physicochemical and microbiological characteristics of honey from Melipona eburnea were evaluated at 90 days following transfer from natural to rational hives. Honey from M. eburnea was also compared with the 90-day-old honey from Melipona grandis, Melipona illota, and Melipona titania. In addition, 180-day-old honey from M. eburnea was sampled and compared with the younger 90-day-old honey. The production of honey varied from 900 to 1400 mL/colony/3 months for M. eburnea. When moisture and total sugars among the different species of Melipona were compared, no significant differences were observed. Neither were there significant differences between the M. eburnea honey at 90 and 180 days of maturation. Microbiological analyses for both treatments had values <0.3/g most probable number (MPN) of coliforms and organisms of fecal origin. Stingless bee honey can therefore be harvested after 3 months, by which time its physicochemical characteristics are stable and it is microbiologically suitable for human consumption.

Soil water repellency in north-eastern Greece with adverse effects of drying on the persistence

Soil Research ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 281 ◽  
Author(s):  
Apostolos K. Ziogas ◽  
Coen J. Ritsema ◽  
Klaas Oostindie ◽  
Louis W. Dekker
Keyword(s):  
Soil Water ◽  
Water Repellency ◽  
Soil Samples ◽  
Water Infiltration ◽  
Agricultural Fields ◽  
Water Repellent ◽  
Soil Water Repellency ◽  
Kiwi Fruit ◽  
Soil Matrix ◽  
North Eastern

Many soils may be water repellent to some degree, challenging the common perception that soil water repellency is only an interesting aberration. When dry, water repellent soils resist or retard water infiltration into the soil matrix. Soil water repellency often leads to the development of unstable wetting and preferential flow paths. In the present study the persistence of water repellency was examined on samples from topsoils in Thrace, north-eastern Greece, using the Water Drop Penetration Time (WDPT) test. The soil samples were collected from agricultural fields throughout the prefectures of Xanthi and Rodopi. Six sites were selected for intensive sampling of water repellency and soil moisture content in transects. Water repellency was measured on field-moist soil samples and after drying the samples at increasing temperatures, to study the influence of drying temperature on the persistence of soil water repellency. Measurements of soil samples taken in agricultural fields under different crops, e.g. winter wheat, tobacco, clover, olive groves, kiwi fruit, and vineyards, in the area of Thrace, revealed that 45% of the locations exhibited actual water repellency during dry periods. Drying of samples from the Sostis site resulted in wettable soil, whereas drying of samples from the Mitriko site increased repellency. Therefore, water repellency should preferably be measured on samples taken in the field under dry conditions in order to reveal and determine the highest persistence of water repellency that might occur in the field.

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