The effect of rate of wetting on water uptake and cohesion of soil crumbs

1954 ◽  
Vol 44 (3) ◽  
pp. 249-253 ◽  
Author(s):  
W. W. Emerson ◽  
G. M. F. Grundy
Keyword(s):  
Soil Sample ◽  
Water Uptake ◽  
Water Movement ◽  
Arable Soil ◽  
The Other ◽  
Cohesive Force ◽  
Laboratory Studies ◽  
Short Columns ◽  
Zero Rate ◽  
Dry Soil

Short columns of air-dry soil crumbs were wetted at different rates and, after draining to a standard suction, the amount of water taken up by each column determined. It was found that this in the other under continuous grass. The extrapolated value of the cohesion of the grassland crumbs at zero rate of wetting was twice that of the arable, indicating an additional cohesive force in the grassland crumbs. The cohesion of the arable soil fell much more rapidly with increased rate of wetting than that of the grassland, probably because the roots in the grassland crumbs provide easy escape passages for the air.The increase, with rate of wetting, of the amount of water held by a soil sample against a given suction is important, at least up to 200 cm. of water. This dependence of the pF curve on rate of wetting is of particular significance for laboratory studies of water movement in soils.

Sexual compatibility in Gonium pectorale (Volvocales: Chlorophyceae) from soil of a single pond

1976 ◽  
Vol 54 (10) ◽  
pp. 1126-1130 ◽  
Author(s):  
Janet R. Stein ◽  
Marion J. McCauley
Keyword(s):  
Soil Sample ◽  
The Other ◽  
Single Sample ◽  
Small Unit ◽  
Sexual Compatibility ◽  
Dry Soil

Clones of Gonium pectorale O.F.M. were crossed in all combinations at 20 °C and the resultant zygotes were examined to determine the degree of sexual compatibility within a single pond (dry soil sample originally). Two distinct groups were recognized within the 31 clones isolated and tested from a single sample, with all the clones in one group incompatible with those of the other. However, members of both groups were compatible with three additional clones. The existence of more than one group of sexually compatible clones isolated from a single soil sample indicates the fallacy of applying the term 'population' to such a sample, although geographically a small unit (<15 cm diam).

scholarly journals Analysis of Soil Water Response to Grass Transpiration

2013 ◽  
Vol 1 (No. 3) ◽  
pp. 85-98
Author(s):  
Dohnal Michal ◽  
Dušek Jaromír ◽  
Vogel Tomáš ◽  
Herza Jiří
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Preferential Flow ◽  
Water Movement ◽  
Control Volume ◽  
Water Pressure ◽  
Lower Boundary ◽  
Root Water Uptake ◽  
Water Dynamics ◽  
Soil Water Dynamics

This paper focuses on numerical modelling of soil water movement in response to the root water uptake that is driven by transpiration. The flow of water in a lysimeter, installed at a grass covered hillslope site in a small headwater catchment, is analysed by means of numerical simulation. The lysimeter system provides a well defined control volume with boundary fluxes measured and soil water pressure continuously monitored. The evapotranspiration intensity is estimated by the Penman-Monteith method and compared with the measured lysimeter soil water loss and the simulated root water uptake. Variably saturated flow of water in the lysimeter is simulated using one-dimensional dual-permeability model based on the numerical solution of the Richards&rsquo; equation. The availability of water for the root water uptake is determined by the evaluation of the plant water stress function, integrated in the soil water flow model. Different lower boundary conditions are tested to compare the soil water dynamics inside and outside the lysimeter. Special attention is paid to the possible influence of the preferential flow effects on the lysimeter soil water balance. The adopted modelling approach provides a useful and flexible framework for numerical analysis of soil water dynamics in response to the plant transpiration.

A field study of reproductive interactions in Bosca's newt, Triturus boscai

1995 ◽  
Vol 16 (4) ◽  
pp. 357-374 ◽  
Author(s):  
Manuel Mouta Faria
Keyword(s):  
Field Study ◽  
Natural Population ◽  
Wild Population ◽  
Short Circuit ◽  
The Other ◽  
Courtship Behaviour ◽  
Laboratory Studies ◽  
Free Living ◽  
Spermatophore Transfer ◽  
Sexual Interference

AbstractObservations of a free-living population of Bosca's newt, Triturus boscai, show that courtship behaviour in nature is similar to the behaviour observed in earlier laboratory studies. Complementary evidence was obtained on the behaviour called flick, which is sometimes inserted at the end of the static display phase, and may be viewed as an equivalent behaviour to the retreat display of the other small-bodied newt species. Sexual interference in the natural population was mainly caused by males. Two characteristic male behaviour patterns were recognised, the waiting position and the push-tail. Females tend to withdraw from situations of interference. Courtship sequences solely consisting of orientation and spermatophore transfer phases, so-called short-circuit sequences, may be interpreted as a male strategy to avoid the very severe male-to-male interference that exists in a wild population.

WATER UPTAKE BY ROOTS IN CRACKS AND WATER MOVEMENT IN CLAYEY SUBSOIL

Soil Science ◽  
1987 ◽  
Vol 143 (5) ◽  
pp. 381 ◽  
Author(s):  
SHUICHI HASEGAWA ◽  
TAIICHIROW SATO
Keyword(s):  
Water Uptake ◽  
Water Movement

scholarly journals Interlaboratory Comparison of Methods To Quantify Microsclerotia of Verticillium dahliae in Soil

1998 ◽  
Vol 64 (10) ◽  
pp. 3846-3853 ◽  
Author(s):  
A. J. Termorshuizen ◽  
J. R. Davis ◽  
G. Gort ◽  
D. C. Harris ◽  
O. C. Huisman ◽  
...  
Keyword(s):  
Verticillium Dahliae ◽  
Interlaboratory Comparison ◽  
Petri Dish ◽  
Soil Samples ◽  
The Other ◽  
Comparison Of Methods ◽  
Research Groups ◽  
Soil Suspension ◽  
Blinded Fashion ◽  
Dry Soil

ABSTRACT In a comparison of different methods for estimatingVerticillium dahliae in soil, 14 soil samples were analyzed in a blinded fashion by 13 research groups in seven countries, using their preferred methods. One group analyzed only four samples. Twelve soil samples were naturally infested, and two had known numbers of microsclerotia of V. dahliae added to them. In addition, a control was included to determine whether transport had an effect on the results. Results differed considerably among the research groups. There was a 118-fold difference between the groups with the lowest and highest mean estimates. Results of the other groups were evenly distributed between these extremes. In general, methods based on plating dry soil samples gave higher numbers of V. dahliae than did plating of an aqueous soil suspension. Recovery of V. dahliae from samples with added microsclerotia varied from 0 to 59%. Most of the variability within each analysis was at the petri dish level. The results indicate the necessity to check the performance of detection assays regularly by comparing recoveries with other laboratories, using a common set of soil samples. We conclude that wet plating assays are less accurate than dry plating assays.

Field tests for ferrous iron and ferric-organic complexes (on exchange sites or in water-soluble forms) in soils

Soil Research ◽  
1981 ◽  
Vol 19 (2) ◽  
pp. 175 ◽  
Author(s):  
CW Childs
Keyword(s):  
Soil Sample ◽  
Field Test ◽  
Ferrous Iron ◽  
Ammonium Acetate ◽  
Field Tests ◽  
Water Soluble ◽  
Organic Ligands ◽  
The Other ◽  
Positive Test ◽  
Organic Complexes

A 1 M solution of ammonium acetate containing �, �-dipyridyl indicator is recommended for use in field tests for exchangeable and water-soluble ferrous iron in soils. In using the test, a soil sample may be added to a vial containing the solution, or the solution can be sprayed on to a freshly exposed soil face. A field test for ferric-organic complexes in soils, using the same vials, is proposed. This is based on the photochemical nature of the reduction of ferric to ferrous iron in the presence of oxidizable organic ligands. Two subsamples of soil are added to separate vials, and light is excluded from one. After 5-15 min, a positive test for ferrous iron in the vial exposed to light, and a negative test in the other, indicates the presence of ferric-organic complexes.

The relationship of Zonocerus variegatus (L.) (Acridoidea: Pyrgomorphidae) with cassava (Manihot esculenta)

1977 ◽  
Vol 67 (3) ◽  
pp. 391-404 ◽  
Author(s):  
E. A. Bernays ◽  
R. F. Chapman ◽  
E. M. Leather ◽  
A. R. McCaffery ◽  
W. W. D. Modder
Keyword(s):  
Hydrogen Cyanide ◽  
Manihot Esculenta ◽  
Normal Growth ◽  
The Other ◽  
Zonocerus Variegatus ◽  
Laboratory Studies ◽  
Low Levels ◽  
Relationship Of ◽  
The Relationship ◽  
Ibadan Nigeria

AbstractField and laboratory studies at Ibadan, Nigeria, showed that the young nymphs of Zonocerus variegatus (L.) normally reject cassava after biting it and die if they are confined on growing leaves. Later instars will eat cassava, especially when deprived of food for some time, but the adults progressively lose weight when restricted to feeding on growing cassava. On cut cassava, on the other hand, extensive feeding occurs and normal growth is maintained. The change from unpalatability to acceptability occurs within about an hour of cutting and is apparently associated with wilting. Cassava produces latex, but this was not distasteful to Zonocerus. The readiness to feed on growing cassava was associated with low levels of hydrogen cyanide production by the leaves; wilted leaves still produced hydrogen cyanide, but at a lower rate than turgid, growing leaves. In the area around Ibadan, Zonocerus regularly defoliates cassava in the latter part of the dry season, probably because a shortage of attractive foods forces the insect to eat cassava.

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