Does soil texture influence the distribution of the greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae), in the Burdekin River sugarcane growing area?

2003 ◽  
Vol 54 (9) ◽  
pp. 861 ◽  
Author(s):  
Andrew L. Ward
Keyword(s):  
Spatial Distribution ◽  
Soil Type ◽  
Laboratory Experiments ◽  
Sandy Soils ◽  
Clay Content ◽  
Larval Survival ◽  
District Level ◽  
Patchy Distribution ◽  
Delta Type ◽  
Series Of Experiments

A series of experiments was undertaken to examine the effect of soil type on the spatial distribution of greyback canegrub in sugarcane in the Burdekin region of Queensland. These experiments examined spatial distribution at a district level as well as within individual fields, using both field and laboratory experiments. The studies concluded that soil type affected canegrub distribution both within fields and within the Burdekin district. However, the mechanisms affecting the distribution at each level were very different. At a regional or district level the preference of greyback canegrub for sandy delta-type soils over soil with higher clay content was hypothesised to be the result of preferential oviposition and improved larval survival in sandy soils over soils with a high clay content. At the field level, cane height was thought to be the primary reason for the patchy distribution of damage, with taller areas being damaged in preference to shorter areas. As all cane is planted or harvested at the same time in each field, differences in cane height between damaged and undamaged areas were thought to be the result of differences in soil type.

A Scientific Search for Altruism

2018 ◽  
Author(s):  
C. Daniel Batson
Keyword(s):  
Human Nature ◽  
Scientific Method ◽  
Laboratory Experiments ◽  
Fundamental Question ◽  
Empathic Concern ◽  
Altruistic Motivation ◽  
The Past ◽  
Past Half Century ◽  
Series Of Experiments ◽  
Past Half

This book provides an example of how the scientific method can be used to address a fundamental question about human nature. For centuries—indeed for millennia—the egoism–altruism debate has echoed through Western thought. Egoism says that the motivation for everything we do, including all of our seemingly selfless acts of care for others, is to gain one or another self-benefit. Altruism, while not denying the force of self-benefit, says that under certain circumstances we can care for others for their sakes, not our own. Over the past half-century, social psychologists have turned to laboratory experiments to provide a scientific resolution of this human nature debate. The experiments focused on the possibility that empathic concern—other-oriented emotion elicited by and congruent with the perceived welfare of someone in need—produces altruistic motivation to remove that need. With carefully constructed experimental designs, these psychologists have tested the nature of the motivation produced by empathic concern, determining whether it is egoistic or altruistic. This series of experiments has provided an answer to a fundamental question about what makes us tick. Framed as a detective story, the book traces this scientific search for altruism through the numerous twists and turns that led to the conclusion that empathy-induced altruism is indeed part of our nature. It then examines the implications of this conclusion—negative implications as well as positive—both for our understanding of who we are as humans and for how we might create a more humane society.

Soil Type, Soil Moisture, and Field Slope Influence the Horizontal Movement of Salmonella enterica and Citrobacter freundii from Floodwater through Soil

2016 ◽  
Vol 80 (1) ◽  
pp. 189-197 ◽  
Author(s):  
MARY THERESA CALLAHAN ◽  
SHIRLEY A. MICALLEF ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Type ◽  
Soil Moisture Content ◽  
Clay Content ◽  
Horizontal Movement ◽  
Initial Soil Moisture ◽  
Salmonella Newport ◽  
Initial Soil ◽  
Rate Of Decline

ABSTRACT Pathogens in soil are readily mobilized by infiltrating water to travel downward through the soil. However, limited data are available on the horizontal movement of pathogens across a field. This study used a model system to evaluate the influence of soil type, initial soil moisture content, and field slope on the movement of Salmonella enterica serovar Newport across a horizontal plane of soil under flooding conditions. Three soil types of varying clay content were moistened to 40, 60, or 80% of their maximum water-holding capacities and flooded with water containing 6 log CFU/ml Salmonella Newport and Citrobacter freundii, the latter being evaluated as a potential surrogate for S. enterica in future field trials. A two-phase linear regression was used to analyze the microbial populations recovered from soil with increasing distance from the flood. This model reflected the presence of lag distances followed by a quantifiable linear decrease in the population of bacteria as a function of the distance from the site of flooding. The magnitude of the lag distance was significantly affected by the soil type, but this was not attributable to the soil clay content. The rate of the linear decline with distance from the flood zone was affected by soil type, initial soil moisture content, and soil incline. As the initial soil moisture content increased, the rate of decline in recovery decreased, indicating greater bacterial transport through soils. When flooding was simulated at the bottom of the soil incline, the rate of decline in recovery was much greater than when flooding was simulated at the top of the incline. There was no significant difference in recovery between Salmonella Newport and C. freundii, indicating that C. freundii may be a suitable surrogate for Salmonella Newport in future field studies.

Two-dimensional Markov Chain Simulation of Soil Type Spatial Distribution

2004 ◽  
Vol 68 (5) ◽  
pp. 1479-1490 ◽  
Author(s):  
Weidong Li ◽  
Chuanrong Zhang ◽  
James E. Burt ◽  
A.-Xing Zhu ◽  
Jan Feyen
Keyword(s):  
Spatial Distribution ◽  
Markov Chain ◽  
Soil Type ◽  
Two Dimensional

EFFECTS OF VEGETATION ON PROPERTIES OF SANDY SOILS IN CENTRAL ALBERTA

1988 ◽  
Vol 68 (2) ◽  
pp. 381-394 ◽  
Author(s):  
J. W. FYLES ◽  
W. B. McGILL
Keyword(s):  
Fire Behavior ◽  
Sandy Soils ◽  
Clay Content ◽  
White Spruce ◽  
Jack Pine ◽  
Parent Material ◽  
Forest Types ◽  
Alder Forest ◽  
Profile Characteristics ◽  
Profile Development

It was hypothesized that topographic location, fire, species characteristics, and soil texture interacted to maintain stable vegetation patterns on the landscape. As a corollary, relationships would exist between specific vegetation and profile development patterns, they would not be masked by secondary succession, and they would explain the distribution of both plant communities and soil types in the landscape. This hypothesis was tested in a study of soils and vegetation at eight sites representing three forest types (pine/lichen; closed canopy jack pine; white spruce) on sand ridges near the town of Slave Lake, Alberta. Differences in profile characteristics among soils studied corresponded to differences in vegetation. Soils under white spruce and jack pine/alder forest showed evidence of greater translocation of amorphous iron and aluminum than soils under jack pine/lichen woodland. The fractionation of phosphorus among organic, Ca–, Al–, and Fe– phosphates differed between soils under the three forest types as did the development of a textural B horizon. Clay eluviation appeared to be dependent primarily on initial clay content of the parent material although a contributory influence of vegetation was suggested. Integration of processes involved in soil profile development with those controlling vegetation dynamics particularly fire behavior, appears to provide a conceptual basis for explaining the distribution of soils in the landscape of the study area. Key words: Central Alberta, vegetation, sandy soils, eluviation, phosphorus fractions, soil development, fire

Denitrification and immobilisation in flood-irrigated alkaline grey clays as affected by nitrification inhibitors, wheat straw, and soil texture

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 633 ◽  
Author(s):  
I. J. Rochester ◽  
G. A. Constable
Keyword(s):  
Wheat Straw ◽  
Soil Texture ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Clay Content ◽  
Field Capacity ◽  
Nitrification Inhibitors ◽  
N Loss ◽  
Waterlogged Soil ◽  
Nitrate N

Published field studies have shown that etridiazole and other nitrification inhibitors may significantly improve N fertiliser recovery in alkaline grey clays. Laboratory experiments were conducted to examine the extent to which nitrification inhibitors could suppress denitrification directly in waterlogged soil, and determine whether this may contribute significantly to the conservation of N fertiliser in the field. Etridiazole reduced the loss of added nitrate-N from waterlogged soil in the short term (days) only. All other nitrification inhibitors failed to suppress N loss. Little nitrate-N was lost from soil maintained at field capacity, whereas 15–85% of applied nitrate was lost from soil that was waterlogged for 10 days. The addition of milled wheat straw encouraged both denitrification and biological N immobilisation to similar extents, although both processes were probably restricted by C availability. Where no straw was added, little N was immobilised and denitrification was halved. Soil texture (clay content) also had a profound influence on N fertiliser recovery (N loss). The laboratory experiments indicated that a component of the responses to etridiazole observed in published field experiments conducted on these soils could be attributed to direct suppression of denitrification by etridiazole.

Hardsetting in the surface horizons of sandy soils and Its implications for soil classification and management

Soil Research ◽  
1994 ◽  
Vol 32 (3) ◽  
pp. 603 ◽  
Author(s):  
RJ Harper ◽  
RJ Gilkes
Keyword(s):  
Organic Matter Content ◽  
Sandy Soils ◽  
Clay Content ◽  
Soil Classification ◽  
Matter Content ◽  
Arid Area ◽  
Plant Performance ◽  
Classification Schemes ◽  
Surface Conditions ◽  
Measured Strength

Marked variations in hardsetting occur in the sandy surface horizons of duplex deep sandy soils in a semi-arid area of Western Australia. Hardsetting by definition only occurs in dry soils and increases with field texture. Soil strength measured on remoulded samples in the laboratory conformed with field assessments of strength (consistence). Most (79%) of the variation in strength between Ap horizon samples was explained by clay content, with small differences in clay content resulting in large differences in strength. Half of the maximum measured strength in the Ap horizons was achieved at a clay content of only 8%. The A2 horizons were markedly stronger than corresponding Ap horizons, despite similar clay contents, and this difference in strength is related to the larger organic matter content of the Ap horizons. Hardsetting of these sandy soils may be explained in terms of the cementing action provided by clay which forms bridges between particles. Organic material weakens these bridges. Hardsetting may affect the wind erodibility of sandy soils, through differences in surface conditions (i.e. loose v. compact) and by increasing the resistance to abrasion by saltating sand. It is not clear what effect it will have on plant performance. Hardsetting is a continuous, rather than discrete soil attribute, and if it is to be described in the field, and used in soil classification schemes, objectives class limits should be defined, perhaps using dry consistence ratings.

Distribution of Phytophthora cinnamomi in the northern jarrah (Eucalyptus marginata) forest of Western Australia in relation to dieback age and topography

2002 ◽  
Vol 50 (1) ◽  
pp. 107 ◽  
Author(s):  
K. L. McDougall ◽  
G. E. St J. Hardy ◽  
R. J. Hobbs
Keyword(s):  
Spatial Distribution ◽  
Western Australia ◽  
Aerial Photography ◽  
Phytophthora Cinnamomi ◽  
Ex Situ ◽  
Patchy Distribution ◽  
Jarrah Forest ◽  
Eucalyptus Marginata ◽  
Almost All

The spatial distribution of Phytophthora cinnamomi Rands at seven dieback sites in the jarrah (Eucalyptus marginata Donn. ex Smith) forest of Western Australia was determined by the following two baiting techniques: in situ baiting with live Banksia grandis Willd. seedlings and ex situ baiting of sampled soil and root material. Four areas within each site were sampled, reflecting dieback age and position in the landscape. Approximate dieback ages of 50, 20 and 5 years were determined by aerial photography. The 50-year-old age class was divided into wet valley floor and dry gravelly slope. Phytophthora cinnamomi was recovered most frequently from the 5-year-old (dieback fronts) and wet 50-year-old areas by both baiting techniques. It was recovered from more than twice as many areas and about five times as many samples when in situ B. grandis baits were used compared with ex situ soil and root baiting. Almost all recoveries from in situ baits were made between October and December. From both methods, it appears that P. cinnamomi has a patchy distribution within dieback sites in the northern jarrah forest. It is easily detected only on dieback fronts and wet valley floors. On dry gravelly sites affected 20 years or more ago, P. cinnamomi is rare and may even be absent at some sites. This makes confident detection of the pathogen difficult. In situ baiting at least allows a temporal component to the sampling and will be a useful method of detection in areas where P. cinnamomi is rare or transient.

Biodegradation of Carbamothioates in Butylate-History Soils

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 818-823 ◽  
Author(s):  
Vicki W. McCusker ◽  
Horace D. Skipper ◽  
Joseph P. Zublena ◽  
Dewitt T. Gooden
Keyword(s):  
Soil Type ◽  
Laboratory Experiments ◽  
Field Conditions ◽  
Lag Phase ◽  
Exponential Rate ◽  
Cross Adaptation ◽  
Enhanced Biodegradation

Laboratory experiments were conducted to evaluate the biodegradation of14C-labeled butylate, cycloate, EPTC, pebulate, and vernolate in three butylate-history soils that had received three to eight applications of butylate under field conditions. After 20 days, biodegradation of butylate and EPTC was accelerated and had no lag phase in all three butylate-history soils. Butylate-adapted microorganisms were cross-adapted for EPTC and degraded EPTC as readily as butylate. Biodegradation of butylate and EPTC in Dothan soil without a butylate history exhibited a lag phase of 6 days after which14CO2was evolved at an exponential rate. This indicated that enhanced biodegradation was induced after one application of butylate or EPTC. Butylate-adapted microorganisms were cross-adapted for vernolate and pebulate in Dothan and pebulate in Wagram soils with a butylate history. Biodegradation of vernolate and pebulate was not enhanced in Varina butylate-history soil. After 20 days, there was no cross-adaptation for cycloate in any soil. These findings indicated that biodegradation of carbamothioates was influenced by soil type and previous carbamothioate use and that caution should be exercised in use of EPTC on fields of previous butylate use.

A Method for Studying the Distribution of Absorbing Roots of Fruit Trees

1971 ◽  
Vol 7 (4) ◽  
pp. 351-362 ◽  
Author(s):  
F. Weller
Keyword(s):  
Spatial Distribution ◽  
Soil Type ◽  
Soil Management ◽  
Root Systems ◽  
Fruit Trees ◽  
Temporal Variations ◽  
Root Tips ◽  
Apple Trees ◽  
Western Germany ◽  
Absorbing Roots

SUMMARYA method is described for studying the distribution of absorbing roots of fruit trees using the number of light root tips per unit of soil space as a criterion for characterizing the spatial distribution of the absorbing parts of the root systems. As examples of the use of this method, some results are shown from investigations with apple trees in South-Western Germany. They demonstrate the influence of soil-type and soil management on the distribution of absorbing roots. Striking temporal variations in the number of root tips were observed in the same tree.

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