scholarly journals Effects of Climate and Soil Type Interactions on Probable Work Days with Harvest Equipment in Mississippi and Alabama Forests

2000 ◽  
Vol 24 (4) ◽  
pp. 213-218
Author(s):  
Jonathan W. Pote ◽  
Charles L. Wax ◽  
Bob L. Karr
Keyword(s):  
Soil Moisture ◽  
Coastal Zone ◽  
Computer Model ◽  
Soil Type ◽  
Sandy Soils ◽  
Clay Soils ◽  
Soil Types ◽  
Probability Level ◽  
Climate Zones

Abstract A computer model predicted soil moisture in three climate zones with three soil textures. A 30 yr daily simulation provided probable work days for the nine combinations. Criteria for work days were soil moisture capacities less than 95% of maximum for sandy soils, 80% for loamy soils, and 65% for clay soils. Results indicate that sandy soils in the inland zone allow 233 work days/yr at the 50% probability level, whereas clay soils there allow only 140 days at that level. In the coastal zone sandy soils allow 252 work days/yr at the 50% level and clay soils allow 122 days at that level. These results were produced at ten probability levels for all soil types and all zones, as well as for each month. Applied examples of uses of the results are included. South. J. Appl. For. 24(4):213-218.

scholarly journals The accuracy of simple soil water models in climate forecasting

1997 ◽  
Vol 1 (2) ◽  
pp. 241-248 ◽  
Author(s):  
E. M. Blyth ◽  
C. C. Daamen
Keyword(s):  
Soil Water ◽  
Sandy Soils ◽  
Clay Soils ◽  
Soil Types ◽  
Layer Model ◽  
Climate Forecasting ◽  
Number Of Layers ◽  
Overall Performance ◽  
Two Layer Model ◽  
Water Models

Abstract. Several simple soil water models with four layers or less, typical of those used in GCMS, are compared to a complex multilayered model. They are tested by applying a repeating wetting/drying cycle at different frequencies, and run to equilibrium. The ability of the simple soil models to reproduce the results of the multilayer model vary according to the frequency of the forcing cycle, the soil type, the number of layers and the depth of the top layer of the model. The best overall performance was from the four layer model. The two layer model with a thin top layer (0.1 m) modelled sandy soils well while the two layer model with a thick top layer (0.5 m) modelled clay soils well. The model with just one layer overestimated evaporation during long drying periods for all soil types.

scholarly journals Influence of cracking clays on satellite estimated and model simulated soil moisture

2010 ◽  
Vol 14 (6) ◽  
pp. 979-990 ◽  
Author(s):  
Y. Y. Liu ◽  
J. P. Evans ◽  
M. F. McCabe ◽  
R. A. M. de Jeu ◽  
A. I. J. M. van Dijk ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Surface Temperature ◽  
Soil Properties ◽  
Surface Soil ◽  
Clay Soils ◽  
Soil Types ◽  
Soil Porosity ◽  
Surface Soil Moisture ◽  
Near Surface ◽  
Community Land Model

Abstract. Vertisols are clay soils that are common in the monsoonal and dry warm regions of the world. One of the characteristics of these soil types is to form deep cracks during periods of extended dry, resulting in significant variation of the soil and hydrologic properties. Understanding the influence of these varying soil properties on the hydrological behavior of the system is of considerable interest, particularly in the retrieval or simulation of soil moisture. In this study we compare surface soil moisture (θ in m3 m−3) retrievals from AMSR-E using the VUA-NASA (Vrije Universiteit Amsterdam in collaboration with NASA) algorithm with simulations from the Community Land Model (CLM) over vertisol regions of mainland Australia. For the three-year period examined here (2003–2005), both products display reasonable agreement during wet periods. During dry periods however, AMSR-E retrieved near surface soil moisture falls below values for surrounding non-clay soils, while CLM simulations are higher. CLM θ are also higher than AMSR-E and their difference keeps increasing throughout these dry periods. To identify the possible causes for these discrepancies, the impacts of land use, topography, soil properties and surface temperature used in the AMSR-E algorithm, together with vegetation density and rainfall patterns, were investigated. However these do not explain the observed θ responses. Qualitative analysis of the retrieval model suggests that the most likely reason for the low AMSR-E θ is the increase in soil porosity and surface roughness resulting from cracking of the soil. To quantitatively identify the role of each factor, more in situ measurements of soil properties that can represent different stages of cracking need to be collected. CLM does not simulate the behavior of cracking soils, including the additional loss of moisture from the soil continuum during drying and the infiltration into cracks during rainfall events, which results in overestimated θ when cracks are present. The hydrological influence of soil physical changes are expected to propagate through the modeled system, such that modeled infiltration, evaporation, surface temperature, surface runoff and groundwater recharge should be interpreted with caution over these soil types when cracks might be present. Introducing temporally dynamic roughness and soil porosity into retrieval algorithms and adding a "cracking clay" module into models are expected to improve the representation of vertisol hydrology.

VARIATION IN MINERAL CONTENT OF SASKATCHEWAN FEED GRAINS

1977 ◽  
Vol 57 (4) ◽  
pp. 679-687 ◽  
Author(s):  
B. D. OWEN ◽  
M. J. FARMER ◽  
F. SOSULSKI ◽  
K. K. WU
Keyword(s):  
Soil Type ◽  
Mineral Content ◽  
Clay Soils ◽  
Seasonal Effects ◽  
Soil Types ◽  
Soil Zone ◽  
Coefficients Of Variation ◽  
Oat Cultivars ◽  
Low Levels ◽  
Gray Soil

The concentration of Ca, P, Mg, K, Zn, Cu, Mn, Fe and Se were determined in wheat, barley and oat cultivars grown in four soil zones incorporating two soil types during a 5-yr period. Ca and K in Saskatchewan grains were much lower than published values, while Zn and Fe values were much higher. Se contents in each grain averaged 0.25 ppm and were substantially below values reported in the literature. Se and Cu levels were extremely variable (CV = 31–81%), but coefficients of variation (CV) for other minerals ranged from 9 to 35%. The effects of season, soil zone, soil type and cultivar on composition of Ca, P, Mg and K were significant in most grains. Seasonal effects on Zn, Cu, Mn and Fe were quite marked, but soil type had little effect and there were few significant differences between cultivars. Grain samples from Gray soil locations were characteristically high in Zn and low in Mn. Average Se content in grain from the Brown soil zone (0.39–0.55 ppm) was highest. There was a progressive decrease through the Dark Brown and Black soils to very low levels in samples from the Gray soil zone (0.06–0.07 ppm). In each type of grain, clay soils were associated with higher Se levels than loam soils.

Efficiency of the salt flotation technique in the recovery of Ascaris lumbricoides eggs from the soil

1995 ◽  
Vol 69 (1) ◽  
pp. 1-5 ◽  
Author(s):  
M.O. Ajala ◽  
S.O. Asaolu
Keyword(s):  
Specific Gravity ◽  
Sandy Soil ◽  
Sodium Nitrate ◽  
Ascaris Lumbricoides ◽  
Soil Type ◽  
Zinc Sulphate ◽  
Sandy Soils ◽  
Soil Types ◽  
Flotation Technique ◽  
Zinc Sulphate Solution

AbstractThe efficacy of the salt flotation technique using saturated solutions of sodium nitrate (specific gravity 1.30) and zinc sulphate (specific gravity 1.16) for separating Ascaris lumbricoides eggs from clay, loamy and sandy soils has been investigated. Ten samples of each of the egg concentrations of 100, 500, 2500, 5000 and 10,000 eggs/25 g of soil were used for each soil type. Using T-test and ANOVA, the number of eggs recovered from sand was significantly higher than from loam and the number from loam significantly higher than from clay. With sodium nitrate, the maximum egg recovery rate was 25.04% from sandy soil at a concentration of 500 eggs/25 g soil while with zinc sulphate it was 13.88% also from sandy soil and concentration of 500 eggs/25 g soil. While the number of eggs recovered increased with soil egg concentration, the percentage of eggs recovered is inversely proportional to egg concentration. The number of eggs recovered with sodium nitrate was significantly higher than with zinc sulphate solution in the three soil types.

Water relations of woody plants on contrasting soils during drought: does edaphic compensation account for dry rainforest distribution?

2009 ◽  
Vol 57 (8) ◽  
pp. 629 ◽  
Author(s):  
Timothy J. Curran ◽  
Peter J. Clarke ◽  
Nigel W. M. Warwick
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Soil Type ◽  
Plant Traits ◽  
Sandy Soils ◽  
Soil Types ◽  
Severe Drought ◽  
Ecotypic Differentiation ◽  
Compensation Hypothesis

The occurrence of dry rainforest in climates considered drier than the recognised limit for rainforest has been explained by the edaphic compensation hypothesis, which proposed that finer-textured soils facilitate the occurrence of rainforest at climatic extremes. We tested this by examining the effect of soil type on the water relations and plant traits of four dry rainforest species, during a severe drought and subsequent non-drought periods. We predicted plants growing in sandy soils would exhibit higher levels of water stress (lower predawn water potential and stomatal conductance) and possess morphological and physiological traits that more typically reflect drought resistance (late leaf fall in deciduous species, low specific leaf area, vertical leaf angles and stomata that close at low water potential) than those growing in loam soils. During drought, levels of water stress were similar across soil types, while post-drought plants on sandy soils were less stressed. Soil type did not cause shifts in drought tolerance traits, suggesting there has been no ecotypic differentiation of dry rainforest species across soil types for these traits. Hence, we found no support for the edaphic compensation hypothesis in adult plants; future studies should consider other life-cycle stages, such as seedlings.

Effects of some soil conditions on sugar-beet seedling emergence

1972 ◽  
Vol 79 (3) ◽  
pp. 543-545 ◽  
Author(s):  
P. C. Longden
Keyword(s):  
Soil Moisture ◽  
Sugar Beet ◽  
Clay Soil ◽  
Sandy Loam ◽  
Seedling Emergence ◽  
Clay Soils ◽  
Soil Types ◽  
Soil Conditions ◽  
Soil Conditioners ◽  
Water Holding

SUMMARYSeven soil conditioners added to a sandy clay soil at Saxmundham did not benefit sugar-beet seedling emergence in four experiments in 3 years. In microplots at Broom's Barn free draining peat and sandy loam gave consistently more seedlings than limestone loam or flinty loam. In the laboratory, for each of three soil types, emergence was maximal only for a small soil moisture range and decreased rapidly when soils became drier or wetter. This suggests that conditioners which increase water-holding capacity should be tested on sandy loams rather than clay soils and that seed-bed preparation on heavier soils should seek to aerate the soil.

Radon emanation and soil moisture effects on airborne gamma‐ray measurements

Geophysics ◽  
1997 ◽  
Vol 62 (5) ◽  
pp. 1379-1385 ◽  
Author(s):  
Robert L. Grasty
Keyword(s):  
Soil Moisture ◽  
Gamma Ray ◽  
Sandy Soils ◽  
Coarse Grained ◽  
Clay Soils ◽  
Radon Emanation ◽  
Airborne Measurements ◽  
Natural Gamma ◽  
Decay Series ◽  
Radon Potential

A theoretical model is developed to explain variations in airborne gamma‐ray measurements over a calibration range near Ottawa, Ontario. The gamma‐ray flux from potassium and the thorium decay series showed an expected decrease with increasing soil moisture. However, the gamma‐ray flux from the uranium decay series was highest in the spring when the ground was water‐saturated and even covered with snow. These results are explained through the build‐up of radon and its associated gamma‐ray—emitting decay products in the clay soil of the calibration range with increasing soil moisture. Similar results were found from airborne measurements over other clay soils. However, measurements over sandy soils showed that the count rates from all three radio elements increased with decreasing soil moisture. This difference between soil types was attributed to the lower radon emanation of the more coarse‐grained sandy soils compared to finer‐grained clay soils. The theoretical and experimental results demonstrate that any estimate of the natural gamma‐ray field caused by radium in the ground must take into consideration the radon emanation coefficient of the soil. The radon diffusion coefficient of the soil must also be considered since it depends strongly on soil moisture. This has significant implications for the assessment of outdoor radiation doses using laboratory analyses of soil samples and the use of ground and airborne gamma‐ray measurements for radon potential mapping.

scholarly journals Occurrence of Peronosclerospora sorghi in Uganda

Plant Disease ◽  
1998 ◽  
Vol 82 (7) ◽  
pp. 757-760 ◽  
Author(s):  
G. Bigirwa ◽  
E. Adipala ◽  
J. P. Esele
Keyword(s):  
Downy Mildew ◽  
Soil Type ◽  
Sandy Soils ◽  
Clay Soils ◽  
Peronosclerospora Sorghi ◽  
Growing Seasons ◽  
Johnson Grass ◽  
High Incidence ◽  
Sorghum Downy Mildew

A study was conducted to determine the occurrence and severity of sorghum downy mildew on three major hosts (maize, sorghum, and Johnson-grass) in Uganda. Five surveys were conducted in four growing seasons, between 1994 and 1995. The disease was encountered in 11 of the 22 districts surveyed. In the majority of the areas, incidence was less than 10%, but it was significantly higher (P < 0.05) in the second season of 1994 than in the first season of 1995. Soil type significantly (P = 0.001) influenced the incidence of sorghum downy mildew, with high incidence being associated with sandy soils, followed by loamy soils, and lowest incidence in clay soils. Incidence, shredding, and oospore production were comparatively higher on sorghum and Johnson-grass than on maize.

Chronic anthropogenic disturbance as a secondary driver of ant community structure: interactions with soil type in Brazilian Caatinga

2016 ◽  
Vol 44 (2) ◽  
pp. 115-123 ◽  
Author(s):  
FERNANDA M. P. OLIVEIRA ◽  
JOSÉ DOMINGOS RIBEIRO-NETO ◽  
ALAN N. ANDERSEN ◽  
INARA R. LEAL
Keyword(s):  
Species Richness ◽  
Soil Type ◽  
Anthropogenic Disturbance ◽  
Model Averaging ◽  
Sandy Soils ◽  
Clay Soils ◽  
Functional Composition ◽  
Human Disturbances ◽  
Ant Community ◽  
Chronic Disturbance

SUMMARYHabitat loss is widely recognized as the major cause of global biodiversity decline, but remaining habitat is increasingly threatened by chronic human disturbances. Using a multi-model averaging approach we examined the association between five chronic disturbance surrogates and the richness and taxonomic and functional composition of ants in Brazilian Caatinga. Using pitfall traps in 47 plots near Parnamirim city (Pernambuco) across two soil types (sand and clay), we recorded 53 species from 27 genera. Ant species richness on sand was slightly higher than on clay, and was negatively related to most surrogates of anthropogenic disturbance. Soil type and human population size were the main predictors of ant species richness. Soil type was the most important predictor of functional group abundance. Taxonomic and functional composition were influenced by soil type and disturbance, but this relationship varied between clay and sandy soils. Ant functional composition showed a weak relationship with disturbance on sandy soils, but on clay soils it showed predictable winner–loser replacement. We attribute the greater effect of disturbance on clay soils to higher intensity of land use, and our study highlights the importance of considering context dependence when evaluating biodiversity responses to disturbance.

scholarly journals Some results of field determinations of the moisture content of soil from thermal conductivity measurements.

1953 ◽  
Vol 1 (2) ◽  
pp. 115-121
Author(s):  
D.A. De Vries
Keyword(s):  
Thermal Conductivity ◽  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Potential Evapotranspiration ◽  
Sandy Soils ◽  
Clay Soils ◽  
Conductivity Measurements ◽  
General Increase ◽  
Moisture Contents

The soil-moisture content at 4-I6-cm depth is compared with precipitation and potential evapotranspiration for periods of one month. During May the moisture contents fluctuated under the influence of frequent rainfall. From the end of May evapotranspiration exceeded precipitation and, during the dry months June and July, rainfall affected only the measurements at 4-cmdepth; moisture contents at 8 and I6 cm became constant after initial drying. During August, rainfall exceeded evapotranspiration and there was a general increase in moisture content. Diurnal variation in moisture content is shown in graphs. For accurate determinations of soil-moisture content from thermal conductivity measurements sandy soils are more suitable than clay soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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