Measurement and simulation of evaporation from a red earth. I. Measurement in a glasshouse using a neutron moisture meter

Soil Research ◽  
1982 ◽  
Vol 20 (2) ◽  
pp. 165 ◽  
Author(s):  
GG Johns
Keyword(s):  
Soil Water ◽  
Prolonged Exposure ◽  
Free Water ◽  
Soil Surface ◽  
Water Evaporation ◽  
Evaporative Demand ◽  
Wide Range ◽  
Moisture Meter ◽  
Neutron Moisture ◽  
Red Earth

The evaporation of water from, and redistribution of water within, intact monoliths (23.6 cm diameter, 60 cm depth) of red earth were studied in a glasshouse under a wide range of evaporative conditions. A neutron moisture meter was appropriately calibrated and used to document changes in the distribution of soil water. This is a novel use for such equipment. Strongly curved and generally different calibrations were required for each depth. Prolonged exposure to highly evaporative environments resulted in the removal from the profile of 90% of water available at matric potentials of between -0.01 and -1.5 MPa within 3 months. Bare soil evaporation was not controlled solely by soil hydraulic parameters as the profile dried, but was influenced by evaporative demand throughout the drying cycle. Only two stages of evaporation were discerned. The first stage, when evaporation from the soil surface was similar to free water evaporation, was virtually non-existent under highly evaporative conditions. The second stage was characterized by a continuous exponential decrease in evaporation. By the end of the drying cycles, evaporation was still decreasing exponentially, with a half-life averaging 34 days. Empirical predictive relationships for the dependence of evaporation on soil water parameters in the surface 10 cm, and evaporativity, were established. These relationships are tested in the following paper.

scholarly journals Evaporation of the soil water in response to the amount of straw and evaporative demand

Agrometeoros ◽  
2018 ◽  
Vol 25 (2) ◽  
Author(s):  
Genei Antonio Dalmago ◽  
Homero Bergamaschi
Keyword(s):  
Soil Water ◽  
Soil Surface ◽  
Bare Soil ◽  
Conventional Tillage ◽  
Water Evaporation ◽  
Weather Variables ◽  
Evaporative Demand ◽  
Randomized Design ◽  
Significant Difference ◽  
Tillage System

This study aimed to evaluate the soil water evaporation in response to the amount of straw on the surface and to the atmospheric evaporative demand. Two experiments were performed in a glass greenhouse at the Federal University of Rio Grande do Sul, in Porto Alegre, Brazil, in 2003. In one experiment, the evaporation was measured with 0, 2, 4, 8 and 16 t ha-1 of oat straw (Avena strigosa) on the soil surface. In another experiment, a fixed covering of 6 t ha-1 of straw was used, and evaporation was measured over five soil drying cycles, displaced in time for promoting different atmospheric demands. A completely randomized design was used in both experiments. Measurements were taken by weighing PVC microlysimeters containing soil monoliths, collected in field areas previously consolidated in no-till and conventional tillage systems. The average evaporation was 24% higher in bare soil than with 16 t ha-1 of straw on the surface. A significant difference was observed among the evaluation cycles, but the evaporation was ever higher in conventional tillage than in no-tilled soil. The vapor pressure deficit of air and the incoming solar radiation were the most important weather variables for the evaporation, regardless of tillage system or straw presence on the soil surface.

Increases in grain yield of wheat by breeding for an osmoregulation gene: relationship to water supply and evaporative demand

2000 ◽  
Vol 51 (8) ◽  
pp. 971 ◽  
Author(s):  
J. M. Morgan
Keyword(s):  
Water Supply ◽  
Field Experiments ◽  
High Efficiency ◽  
Free Water ◽  
Water Evaporation ◽  
Yield Response ◽  
Evaporative Demand ◽  
Potential Yield ◽  
Pollen Selection ◽  
Wide Range

The effect of water stress on yield increases produced by breeding for an osmoregulation gene (or) was examined using both backcross-bred lines (produced using allele identification in pollen grains) and inbred lines (produced using leaf tests). Yields were measured in 39 field experiments spanning 8 seasons. These included experiments where water was supplied through drip irrigators and rain excluded with a mobile shelter. Several approaches to the measurement of stress environment were examined. The commonly used site mean yield, although most accessible and so utilising the most data, was least effective in explaining variation in yield response. Comparatively high efficiency (84%) could be achieved using measurements of rainfall or evaporative demand for specific periods of crop ontogeny, but this suffered the limitation of being season or treatment specific. The results did, however, demonstrate the value of the pollen selection method in increasing yield under conditions of reduced water supply. In keeping with past climatic analyses, and with the theory underlying variations in leaf water potential to which osmoregulation responds, an index incorporating water supply and evaporative demand accounted well for the yield increase (85%) over the wide range of seasons and treatments examined. It requires inputs of available soil water at sowing, rainfall, and free-water evaporation during the growing period, together with sowing and anthesis dates. The index was used to assess potential yield responses in the various climates covered by the Australian wheatbelt. Greatest potential lay at the drier, inland, margins especially where soils are lighter and water-holding capacities lower.

scholarly journals Characteristics of Soil Moisture and Evaporation under the Activities of Earthworms in Typical Anthrosols in China

2020 ◽  
Vol 12 (16) ◽  
pp. 6603
Author(s):  
Li Ma ◽  
Ming’an Shao ◽  
Tongchuan Li
Keyword(s):  
Soil Temperature ◽  
Soil Water ◽  
Agricultural Development ◽  
Soil Layer ◽  
Soil Surface ◽  
Soil Evaporation ◽  
Water Evaporation ◽  
Soil Columns ◽  
Soil Surface Temperature ◽  
Water Holding

Earthworms have an important influence on the terrestrial ecological environment. This study assesses the effect of different earthworm densities on soil water content (SWC) and evaporation in a laboratory experiment. Four earthworm densities (0 no-earthworm, control [C]; 207 earthworms m−2, low density [LDE]; 345 earthworms m−2, medium density [MDE]; and 690 earthworms m−2, high density [HDE]) are tested in soil columns. Results show that cumulative evaporation occurs in the decreasing order of densities: C (98.6 mm) > LDE (115.8 mm) > MDE (118.4 mm) > HDE (124.6 mm). Compared with the control, earthworm activity decreases cumulative soil evaporation by 5.0–20.9%, increases soil temperature to 0.46 °C–0.63 °C at 8:00, and decreases soil temperature to 0.21 °C–0.52 °C at 14:00 on the soil surface. Temperature fluctuations reduce with increasing earthworm densities. A negative correlation is found between cumulative soil evaporation and earthworm density (R2 = 0.969, p < 0.001). Earthworms significantly (p < 0.05) decrease the surface SWC loss (0–20 cm) soil layer but increase the subsoil SWC loss (60–100 cm) by adjusting the soil temperature and reducing soil water evaporation. Earthworm activities (burrows, casts…) improve the soil water holding ability by adjusting soil temperature and reducing soil water evaporation. Thus, the population quantity of earthworms may provide valuable ecosystem services in soil water and heat cycles to save water resources and realize sustainable agricultural development.

A model for estimating soil moisture deficits under cereal crops in Britain:1. Development

1982 ◽  
Vol 98 (3) ◽  
pp. 651-661 ◽  
Author(s):  
P. E. Francis ◽  
J. D Pidgeon
Keyword(s):  
Potential Evapotranspiration ◽  
System Development ◽  
Free Water ◽  
Soil Surface ◽  
Cereal Crops ◽  
Water Losses ◽  
Crop Species ◽  
Detailed Model ◽  
Stage Of Development ◽  
Wide Range

SUMMARYA new and detailed model, involving meteorological, crop and soil variables, is proposed to provide daily estimates of moisture deficits in soils under cereal cropping in Britain. The model incorporates developments in the calculation of potential evapotranspiration specifically for cereal crops. Four processes of loss of water are considered, namely drainage, evaporation of free water from the crop canopy, evaporation from the soil surface and transpiration by the crop. Thus the model is applicable at all stages of the cropping cycle. Above-ground and root system development of the crop are modelled and available and extractable water capacities of a wide range of soils are estimated. Thus the demand for water and its availability are varied with crop species, stage of development and soil type as well as with meteorological variables.The calculation of water losses is not dependent on arbitrary assumptions about the division of losses between the four processes considered or between different horizons of the soil.Extreme simplicity of input data requirement has been maintained. The model has been programmed in FORTRAN, and is compatible with Meteorological Office data archives.

scholarly journals Effect of mulching and subsurface drip irrigation on soil water status under arid environment

2020 ◽  
Vol 18 (1) ◽  
pp. e1201
Author(s):  
Ahmed A. Al-Othman ◽  
Mohamed A. Mattar ◽  
Mohammed A. Alsamhan
Keyword(s):  
Soil Water ◽  
Drip Irrigation ◽  
Agricultural Research ◽  
Water Status ◽  
Soil Surface ◽  
Subsurface Drip Irrigation ◽  
Water Evaporation ◽  
Water Retention Capacity ◽  
Palm Tree ◽  
Subsurface Drip

Aim of study: We investigated water evaporation of the soil surface and the soil water distribution under different mulching techniques using subsurface drip irrigation (SDI) system.Area of study: The experiment was conducted at the Agricultural Research and Experimental Farm in Dirab, Riyadh, Saudi Arabia, locating 24.4195° N, 46.65° E, and 552 m altitude.Material and methods: The two types of soil surface mulching were black plastic film (BPF) and palm tree waste (PTW), with no mulching (NM) as control. The two drip line depths from the soil surface (DL) were 15 cm and 25 cm, and surface drip irrigation (DI) was the control.Main results: In SDI, the use of BPF or PTW mulching resulted in enhanced water retention capacity of the soil and an approximately 6% water saving, compared with NM. The amounts of water saved at DL of 15 cm (19-24 mm) were greater than those at DL of 25 cm (15-20 mm), whereas the DI used the highest amount of applied water. The distribution of soil water content for BPF and PTW were found to be more uniform than NM.Research highlights: It is advised to mulch the soil with PTW due to lower costs and through a DL of 15 cm.

Screening potato clones for resistance to common scab (Streptomyces scabies) in the field

1972 ◽  
Vol 79 (1) ◽  
pp. 75-81 ◽  
Author(s):  
F. A. Langton
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Common Scab ◽  
Severe Infection ◽  
Field Capacity ◽  
Streptomyces Scabies ◽  
Screening Tests ◽  
Moisture Meter ◽  
Neutron Moisture

SUMMARYPotato varieties were grown in the field in soil uniformly infected with Streptomyces scabies. In 1969 tubers were severely and evenly infected but in 1971 infection was slight and not uniform. Agreement of varietal ranking with agricultural experience was good in 1969 but poor in 1971.In 1971, plots protected from rainfall after planting were dry enough at the start of tubering for severe infection; covering the plots for a further 6 weeks followed by irrigation to field capacity resulted in good yields of evenly and severely scabbed tubers. Irrigation during this period suppressed scabbing. The results were easily interpreted in relation to fluctuations in soil-water content measured by a neutron moisture-meter.The efficiency of using only one site and the need to reduce variability in scab screening tests are discussed.

scholarly journals Interactions between plant nutrients, water and carbon dioxide as factors limiting crop yields

1997 ◽  
Vol 352 (1356) ◽  
pp. 987-996 ◽  
Author(s):  
P. J. Gregory ◽  
L. P. Simmonds ◽  
G. P. Warren
Keyword(s):  
Soil Water ◽  
Biomass Production ◽  
Crop Yields ◽  
Soil Surface ◽  
Nutrient Supply ◽  
Nutrient Loss ◽  
Evaporative Demand ◽  
Unsaturated Hydraulic Conductivity ◽  
Management Techniques ◽  
Rate Of Evaporation

Biomass production of annual crops is often directly proportional to the amounts of radiation intercepted, water transpired and nutrients taken up. In many places the amount of rainfall during the period of rapid crop growth is less than the potential rate of evaporation, so that depletion of stored soil water is commonplace. The rate of mineralization of nitrogen (N) from organic matter and the processes of nutrient loss are closely related to the availability of soil water. Results from Kenya indicate the rapid changes in nitrate availability following rain. Nutrient supply has a large effect on the quantity of radiation intercepted and hence, biomass production. There is considerable scope for encouraging canopy expansion to conserve water by reducing evaporation from the soil surface in environments where it is frequently rewetted, and where the unsaturated hydraulic conductivity of the soil is sufficient to supply water at the energy limited rate (e.g. northern Syria). In regions with high evaporative demand and coarse–textured soils (e.g. Niger), transpiration may be increased by management techniques that reduce drainage. Increases in atmospheric [CO 2 ] are likely to have only a small impact on crop yields when allowance is made for the interacting effects of temperature, and water and nutrient supply.

scholarly journals Sensible Heat Observations Reveal Soil-Water Evaporation Dynamics

2008 ◽  
Vol 9 (1) ◽  
pp. 165-171 ◽  
Author(s):  
J. L. Heitman ◽  
R. Horton ◽  
T. J. Sauer ◽  
T. M. DeSutter
Keyword(s):  
Heat Flux ◽  
Soil Water ◽  
Heat Balance ◽  
Measurement Techniques ◽  
Sensible Heat Flux ◽  
Soil Surface ◽  
Water Evaporation ◽  
Sensible Heat ◽  
Near Surface ◽  
Evaporation Zone

Abstract Soil-water evaporation is important at scales ranging from microbial ecology to large-scale climate. Yet routine measurements are unable to capture rapidly shifting near-surface soil heat and water processes involved in soil-water evaporation. The objective of this study was to determine the depth and location of the evaporation zone within soil. Three-needle heat-pulse sensors were used to monitor soil heat capacity, thermal conductivity, and temperature below a bare soil surface in central Iowa during natural wetting/drying cycles. Soil heat flux and changes in heat storage were calculated from these data to obtain a balance of sensible heat components. The residual from this balance, attributed to latent heat from water vaporization, provides an estimate of in situ soil-water evaporation. As the soil dried following rainfall, results show divergence in the soil sensible heat flux with depth. Divergence in the heat flux indicates the location of a heat sink associated with soil-water evaporation. Evaporation estimates from the sensible heat balance provide depth and time patterns consistent with observed soil-water depletion patterns. Immediately after rainfall, evaporation occurred near the soil surface. Within 6 days after rainfall, the evaporation zone proceeded &gt; 13 mm into the soil profile. Evaporation rates at the 3-mm depth reached peak values &gt; 0.25 mm h−1. Evaporation occurred simultaneously at multiple measured depth increments, but with time lag between peak evaporation rates for depths deeper below the soil surface. Implementation of finescale measurement techniques for the soil sensible heat balance provides a new opportunity to improve understanding of soil-water evaporation.

Evapotranspiration of Safflower at three densities of sowing

1965 ◽  
Vol 16 (6) ◽  
pp. 961 ◽  
Author(s):  
WR Stern
Keyword(s):  
Soil Water ◽  
Transition Period ◽  
Root Zone ◽  
Free Water ◽  
Soil Water Storage ◽  
Water Evaporation ◽  
Low Latitude ◽  
Type Curve ◽  
Area Index ◽  
Irrigated Crops

In a low latitude environment, evapotranspiration from irrigated crops of safflower growing at low, middle, and high densities was determined from changes in soil water storage. Evapotranspiration was related to potential free water evaporation as calculated by the Penman formula. Except at the rosette stage and during the transition period leading to elongation, there was no measurable difference in evapotranspiration between densities. The ratio of evapotranspiration to free water evaporation was 1.57 during elongation and 1.25 between elongation and flowering, falling to less than 1 before the last irrigation and before any marked depletion of soil water in the root zone. Average evapotranspiration over the cropping period was 3.1 mm day-l and the transpiration ratio 342. Leaf area index and evapotranspiration rates were related by a Mitscherlich type curve with an evapotranspiration plateau of 4.2 mm day-1. The high ratios of evapotranspiration to potential evaporation were due to bulk advective conditions in this environment. The observed evapotranspiration is discussed in relation to the growth of the crop and the variations observed in the field.

Sign in / Sign up

Export Citation Format

Share Document