Redistribution of water following precipitation on previously dry sandy soils

Soil Research ◽  
1975 ◽  
Vol 13 (1) ◽  
pp. 13 ◽  
Author(s):  
BA Carbon

Theoretical and experimental evidence is provided to show that the redistribution of a given amount of water some days after infiltration into a previously dry soil can be predicted, provided that the relationship between soil water potential and soil water content is known. The capillary potential at the wetting front during infiltration into the dry soil is also required. In sandy soils an increase in amount of applied water leads to a decrease in the soil moisture content at the soil surface. This change in 'field capacity' as a function of applied water is shown to strongly influence seedling emergence.

2002 ◽  
Vol 82 (4) ◽  
pp. 855-859 ◽  
Author(s):  
M. L. Leblanc ◽  
D. C. Cloutier ◽  
C. Hamel

A 2-year field study was conducted in corn to determine the influence of rainfall, irrigation and soil water content on common lambsquarters and barnyardgrass emergence. Rainfall or irrigation had no influence on the final weed density and little on the pattern of weed emergence because the soil water content was at or greater than field capacity during the main weed emergence period. Irrigation may hasten the first weed emergence by warming the soil when temperature is limiting for germination. In southwestern Quebec, temperature appears to be the most important factor regulating germination in the spring since soil moisture is normally at field capacity for a long period, in part because of the melting of snow. Key words: Irrigation, weed emergence, soil moisture


1977 ◽  
Vol 7 (4) ◽  
pp. 595-604 ◽  
Author(s):  
C. S. Tan ◽  
T. A. Black ◽  
J. U. Nnyamah

As part of a 2-year study of the effect of thinning on evapotranspiration in Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), the relationship between stomatal diffusion resistance (rs) and environmental variables were studied. Research was conducted in an unthinned stand (1840 stems ha−1) with negligible undergrowth and a thinned stand (840 stems ha−1) with substantial salal (Gaultheriashallon Pursh) undergrowth. During the daytime rs was mainly related to the soil water potential (ψs) and the vapour pressure deficit (v.p.d.) of the canopy air. Daytime values of rs for Douglas fir ranged from 2 to 60 s cm−1 for values of v.p.d. between 4 and 24 mb (4 and 24 × 102 Pa) and values of ψs between 0 and −12.5 bars (0 and −12.5 × 105 Pa). Although increasing rs was usually associated with decreasing pressure potential of the twig xylem (ψt), increasing rs appeared to be associated with increasing ψt when the v.p.d. was high. Stress history was found to cause a shift in the relationship of rs to ψt, but had little effect on the relationship of rs to v.p.d. and ψs. Daytime values of rs for salal ranged from 2 to 45 s cm−1. This stomatal behaviour suggests that as the soil dried out, salal transpiration accounted for an increasing fraction of the total water loss by the thinned stand.


1992 ◽  
Vol 29 (6) ◽  
pp. 1060-1070 ◽  
Author(s):  
Raymond N. Yong ◽  
Abdel Mohsen O. Mohamed

The results of infiltration (wetting) experiments conducted on expansive soils demonstrate several requirements and constraints to the techniques used for the study of wetting performance of such soils. In part, these constraints are a necessary outcome of limitations imposed by the difficulties (impossibility?) of measurement of swelling pressure at the wetting front. To provide a better insight into the development of swelling and reaction pressure in the soil during the wetting process, the energies of interaction between particles and water are examined, especially in regard to those forces developed in the Stern layer. The Grahame modification of the Stern layer has been used in this study to provide the basis for calculations of interaction energies in the inner and outer Helmholtz planes. Comparison with high-pressure consolidation of a sodium montmorillonite at very close particle separation distances suggests that the addition of the energies of interaction developed in the Stern layer to the Gouy–Chapman model would permit the double-layer model to be extended to close particle spacings. Whether this is sufficient to account for the stage I wetting process is a question that remains to be further studied. For the present, the test results suggest that the expression for the total soil–water potential ψ should account for those forces of interaction, thereby providing a better account of the physical processes involved in wetting of the expansive clay and a more realistic diffusion coefficient for the total wetting process. Key words : soil-water potential, osmotic potential, swelling pressure, volume change, wetting front, Stern layer, inner Helmholtz plane, outer Helmholtz plane, Coulombic forces, dipole–dipole interaction, ion–dipole interaction.


2006 ◽  
Vol 144 (3) ◽  
pp. 229-235 ◽  
Author(s):  
S. G. SOMMER ◽  
L. S. JENSEN ◽  
S. B. CLAUSEN ◽  
H. T. SØGAARD

Volatilization of ammonia (NH3) from slurry applied in the field is considered a risk to the environment and reduces the fertilizer value of the slurry. To reduce volatilization a better understanding of the slurry–soil interaction is needed. Therefore, the present study focuses on measuring NH3 volatilization as affected by differences in infiltration. Livestock slurries with different dry matter (DM) composition and viscosity were included in the experiments by using untreated cattle and pig slurry, pig slurry anaerobically digested in a biogas plant and pig slurry anaerobically digested and physically separated. NH3 volatilization was measured using dynamic chambers and related to infiltration of the livestock slurries in the soil by measuring chloride (Cl−) and Total Ammoniacal Nitrogen (TAN=ammonium (NH4+)+NH3) concentrations in soil at different depths from 0·5 to 6·0 cm from the soil surface. The slurries were applied to sandy and sandy-loam soils packed in boxes within the chambers. There were no significant differences in relative volatilization of NH3 from untreated cattle and pig slurries, but anaerobic digestion of pig slurry increased volatilization due to increases in pH. However, physical separation of the digested slurry reduced the volatilization compared with untreated slurry, due to increased infiltration. In general, the volatilization decreased significantly with increased infiltration. The present study shows that NH3 volatilization from applied slurry can be related to infiltration and that infiltration is related to slurry composition (i.e. DM content and particle size distribution) and soil water content. The infiltration of liquid (measured by Cl− infiltration) was affected by soil water potential, therefore, Cl− infiltrated deeper into the sandy loam soil than the sandy soil at similar gravimetric soil water values. Dry matter (DM) and large particles (>1 mm) of the slurry reduced infiltration of liquid. A high proportion of small particles (<0·025 mm) facilitated infiltration of TAN.


HortScience ◽  
1990 ◽  
Vol 25 (8) ◽  
pp. 928-929 ◽  
Author(s):  
R.E. Gaussoin ◽  
J.A. Murphy ◽  
B.E. Branham

A method for measuring soil water potential in field soils was adapted for use in turfgrass soils. The system uses tensiometers installed flush with the soil surface and permits a measuring depth as shallow as 2.5 to 5.0 cm. Water potential within a tensiometer was measured with a portable pressure transducer. Linear relationships between water potential measured with mercury manometers or vacuum gauge-equipped tensiometers and the pressure transducer were obtained (r2 = 0.99 and 0.97, respectively). The system accurately measures soil water potential of turfgrass soils, while permitting routine cultural practices to be performed.


Author(s):  
Sukanta Kumar Das

The study has been attempted to investigate the relationship between the soil-water and the Indian summer monsoon (ISM) rainfall through the simulation of a global climate model named Community Atmosphere Model (CAM3). Two sets of simulation have been done during monsoon season for the years 2009 to 2012 using the pre-monsoon (May) and the previous winter season (December of previous year) state of soil-water as the model initial conditions. The control simulation and four sensitivity cases assuming 25% and 50% dryer and wetter soil-water respectively have been considered for all the aforesaid four years and for both the set of experiments. It has been observed that the impact of upper level soil-water persist for 15 to 20 days of simulation during the summer monsoon; the middle and lower layer soil state persist for a longer period of time due to its slow-varying nature with time. The daily surface temperature shows strong coupling with the upper layer of soil-water. When taken into comparison with the wet soil conditions, the dry soil state in most of the circumstances causes less rainfall.  The Pearson correlation coefficient (PCC) and partial correlation technique have been implied to demonstrate the relationship between the daily soil-water columns, subsequent 30-days accumulated rainfall and past 21-days accumulated rainfall. Strong negative correlation has been reported between the soil-water and subsequent 30-days accumulated (All-India Rainfall) AIR for different simulation cases with dry soil conditions; however, the relation weakened and turned positive over some parts of the region for the simulations with wet soil conditions.


2010 ◽  
Vol 56 (No. 7) ◽  
pp. 333-339 ◽  
Author(s):  
A.A.S. Sinegani ◽  
A. Mahohi

To better understand how water stress and availability affect the enzyme activity and microbial communities in soil, we measured the changes of organic carbon (OC), bacteria and fungi populations, and endoglucanase and exoglucanase activities in a semiarid soil treated with air-dried primary sewage sludge at a rate of 20 g/kg. The water potentials established for soil incubation were: saturation (SA, 0 bar), field capacity (FC, &ndash;0.3 bar), and permanent wilting point (PWP, &ndash;15 bar). An irrigation treatment was a drying-rewetting cycle (DWC) between &ndash;0.3 to &ndash;15 bars. After 0, 20, 60 and 90 days of incubation soils were sampled for analysis. The addition of sewage sludge increased soil OC, endoglucanase and exoglucanase activities significantly. The effects of soil moisture, incubation time and their interactions on OC, and endoglucanase and exoglucanase activities in soil were significant. During 20 days of incubation, OC, endoglucanase and exoglucanase activities decreased significantly. Soils incubated in DWC and FC compared to soils incubated in SA and PWP had lower OC contents due to organic matter mineralization. Organic C, exoglucanase and endoglucanase activities significantly increased with increasing soil water potential. The activities of exoglucanase and endoglucanase in soils incubated in SA were significantly higher than those in soils incubated in PWP.


2013 ◽  
Vol 33 (2) ◽  
pp. 269-278 ◽  
Author(s):  
Adão W. P. Evangelista ◽  
Luiz A. Lima ◽  
Antônio C. da Silva ◽  
Carla de P. Martins ◽  
Moisés S. Ribeiro

Irrigation management can be established, considering the soil water potential, as the limiting factor for plant growth, assuming the soil water content between the field capacity and the permanent wilting point as available water for crops. Thus, the aim of this study was to establish the soil water potential interval during four different phenological phases of coffee irrigated by center pivot. The experiment was set at the experimental area of the Engineering Department at the Federal University of Lavras, in Brazil. The coffee variety planted is designated as Rubi, planted 0.8 meters apart, with rows spaced 3.5 meters apart. The treatments corresponded to the water depths applied based on different percentages of Kc and reference evapotranspiration (ET0) values. Sensors were used to measure the soil water potential interval, installed 25 centimeters depth. In order to compare the results, it was considered as the best matric potential the one that was balanced with the soil water content that resulted in the largest coffee productivity. Based on the obtained results, we verified that in the phases of fruit expansion and ripening, the best results were obtained, before the irrigations, when the soil water potential values reached -35 and -38 kPa, respectively. And in the flowering, small green and fruit expansion phases, when the values reached -31 and -32 kPa, respectively.


2021 ◽  
Vol 47 (3) ◽  
pp. 110-115
Author(s):  
Johannes Hertzler ◽  
Steffen Rust

Soil water potential can be used as a proxy for plant available water in irrigation scheduling. This study investigated the relationship between soil water potential and plant water status of pines (Pinus sylvestris L.) planted into two different substrates. Predawn leaf water potential as a well-established measure of the plant water status and soil water potential correlated very well. However, estimating the plant water status from individual sensor readings is subject to significant estimation errors. Furthermore, it was shown that heterogeneous soil/root ball combinations can lead to critical effects on the soil water balance, and that sensors installed outside of the root balls cannot estimate the plant water status without site-specific calibration.


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