scholarly journals Difference in Canopy and Air Temperature as an Indicator of Grassland Water Stress

2013 ◽  
Vol 1 (No. 4) ◽  
pp. 127-138 ◽  
Author(s):  
Duffková Renata
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Air Temperature ◽  
Temperature Difference ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Plant Residues ◽  
Dead Plant ◽  
Linear Correlations

In 2003–2005 in conditions of the moderately warm region of the Třeboň Basin (Czech Republic) the difference between canopy temperature (Tc) and air temperature at 2 m (Ta) was tested as an indicator of grass­land water stress. To evaluate water stress ten-minute averages of temperature difference Tc–Ta were chosen recorded on days without rainfall with intensive solar radiation from 11.00 to 14.00 CET. Water stress in the zone of the major portion of root biomass (0–0.2 m) in the peak growing season (minimum presence of dead plant residues) documented by a sudden increase in temperature difference, its value 5–12°C and unfavourable canopy temperatures due to overheating (> 30°C) was indicated after high values of suction pressure approach­ing the wilting point (1300 kPa) were reached. High variability of temperature difference in the conditions of sufficient supply of water to plants was explained by the amount of dead plant residues in canopy, value of va­pour pressure deficit (VPD), actual evapotranspiration rate (ETA) and soil moisture content. At the beginning of the growing season (presence of dead plant residues and voids) we proved moderately strong negative linear correlations of Tc–Ta with VPD and Tc–Ta with ETA rate and moderately strong positive linear correlations of ETA rate with VPD. In the period of intensive growth (the coverage of dead plant residues and voids lower than 10%) moderately strong linear correlations of Tc–Ta with VPD and multiple linear correlations of Tc–Ta with VPD and soil moisture content at a depth of 0.10–0.40 m were demonstrated.

scholarly journals RESEARCH NOTEA comparison between reference transpiration and measurements of evaporation for a riparian grassland site

1998 ◽  
Vol 2 (1) ◽  
pp. 129-136 ◽  
Author(s):  
J. W. Finch ◽  
R. J. Harding
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Free Water ◽  
Eddy Correlation ◽  
Meteorological Variables ◽  
Direct Measurements ◽  
Riparian Grassland ◽  
Grassland Site

Abstract. This paper compares direct measurements of evaporation with the values predicted for reference transpiration. The measurements of actual evaporation were made using an eddy correlation device on a grass field adjacent to the river Thames. Measurements of soil moisture and the driving meteorological variables were also made. The results showed that, during a period with minimal rainfall but no water stress, the cumulative values of reference transpiration compared very well with the cumulative measured evaporation and changes in soil moisture content. However, the values on specific days did not compare well. Following significant rainfall, the measured evaporation increased for a few days, probably due to evaporation of free water from the canopy or soil. Reference transpiration fell consistently below the measured evaporation once the soil moisture deficits exceeded 140 to 150 mm.

scholarly journals Numerical Simulations of Effects of Soil Moisture and Modification by Mountains over New Zealand in Summer

2011 ◽  
Vol 139 (2) ◽  
pp. 494-510 ◽  
Author(s):  
Yang Yang ◽  
Michael Uddstrom ◽  
Mike Revell ◽  
Phil Andrews ◽  
Hilary Oliver ◽  
...  
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Moisture Content ◽  
Air Temperature ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Surface Air Temperature ◽  
Shortwave Radiation ◽  
Lower Sensitivity ◽  
The South

Abstract Historically most soil moisture–land surface impact studies have focused on continents because of the important forecasting and climate implications involved. For a relatively small isolated mountainous landmass in the ocean such as New Zealand, these impacts have received less attention. This paper addresses some of these issues for New Zealand through numerical experiments with a regional configuration of the Met Office Unified Model atmospheric model. Two pairs of idealized simulations with only contrasting dry or wet initial soil moisture over a 6-day period in January 2004 were conducted, with one pair using realistic terrain and the other pair flat terrain. For the mean of the 6 days, the differences in the simulated surface air temperature between the dry and moist cases were 3–5 K on the leeside slopes and 1–2 K on the windward slopes and the central leeside coastal region of the South Island in the afternoon. This quite nonuniform response in surface air temperature to a uniformly distributed soil moisture content and soil type is mainly attributed to modification of the effects of soil moisture by mountains through two different processes: 1) spatial variation in cloud coverage across the mountains ranges leading to more shortwave radiation at ground surface on the leeside slope than the windward slope, and 2) the presence of a dynamically and thermally induced onshore flow on the leeside coast bringing in air with a lower sensitivity to soil moisture. The response of local winds to soil moisture content is through direct or indirect effects. The direct effect is due to the thermal contrast between land and sea/land shown for the leeside solenoidal circulations, and the indirect effect is through the weakening of the upstream blocking of the South Island for dryer soils shown by the weakening and onshore shift of the upstream deceleration and forced ascent of incoming airflow.

scholarly journals Assessment of Drought Tolerance of Miscanthus Genotypes through Dry-Down Treatment and Fixed-Soil-Moisture-Content Techniques

Agriculture ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 6
Author(s):  
Tzu-Ya Weng ◽  
Taiken Nakashima ◽  
Antonio Villanueva-Morales ◽  
J. Ryan Stewart ◽  
Erik J. Sacks ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Drought Tolerance ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Influential Factor ◽  
Miscanthus Sinensis ◽  
Genetic Cluster ◽  
Drought Tolerant ◽  
Dry Down

Miscanthus, a high-yielding, warm-season C4 grass, shows promise as a potential bioenergy crop in temperate regions. However, drought may restrain productivity of most genotypes. In this study, total 29 Miscanthus genotypes of East-Asian origin were screened for drought tolerance with two methods, a dry-down treatment in two locations and a system where soil moisture content (SMC) was maintained at fixed levels using an automatic irrigation system in one location. One genotype, Miscanthus sinensis PMS-285, showed relatively high drought-tolerance capacity under moderate drought stress. Miscanthus sinensis PMS-285, aligned with the M. sinensis ‘Yangtze-Qinling’ genetic cluster, had relatively high principal component analysis ranking values in both two locations experiments, Hokkaido University and Brigham Young University. Genotypes derived from the ‘Yangtze-Qinling’ genetic cluster showed relatively greater photosynthetic performance than other genetic clusters, suggesting germplasm from this group could be a potential source of drought-tolerant plant material. Diploid genotypes showed stronger drought tolerance than tetraploid genotypes, suggesting ploidy could be an influential factor for this trait. Of the two methods, the dry-down treatment appears more suitable for selecting drought-tolerant genotypes given that it reflects water-stress conditions in the field. However, the fixed-SMC experiment may be good for understanding the physiological responses of plants to relatively constant water-stress levels.

scholarly journals Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

2012 ◽  
Vol 9 (12) ◽  
pp. 5373-5389 ◽  
Author(s):  
M. Wilkinson ◽  
E. L. Eaton ◽  
M. S. J. Broadmeadow ◽  
J. I. L. Morison
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Eddy Covariance ◽  
Carbon Balance ◽  
Annual Variation ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Co2 Uptake ◽  
Growing Season Length ◽  
Net Co2 Uptake

Abstract. The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999–2010). The mean annual net ecosystem productivity (NEP) was 486 g C m−2 yr−1 (95% CI of ±73 g C m−2 yr−1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m−2 yr−1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m−2 yr−1. Although the maximum variation of NEP between years was large (333 g C m−2 yr−1), the ratio of Reco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p < 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest was a substantial sink of carbon over the 12-yr measurement period.

scholarly journals The effect of rainfall and extensive use of grasslands on water regime

2011 ◽  
Vol 48 (No. 3) ◽  
pp. 89-95
Author(s):  
R. Duffková
Keyword(s):  
Land Use ◽  
Soil Moisture ◽  
Moisture Content ◽  
Water Regime ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Water Runoff ◽  
Botanical Composition ◽  
Significant Difference ◽  
Determinant Factor

&nbsp;Water regimes of extensively used grasslands (one cut per year, two cuts per year, no cut, mulching) were determined and compared by drainage lysimeters in 1998&ndash;2000. Although the botanical composition and yields of experimental swards were different, there was no statistically significant difference in their water regime (only the soil moisture content of no-cut variant was significantly higher than in other variants). A&nbsp;determinant factor for the water regime of grasslands (GR) is the sum of rainfall over the growing season while the GR water regime is influenced by land use immediately after the cut. Water runoff from the soil profile 0.0&ndash;0.60 m (water supply to the groundwater level) was found to be negligible in the growing season, a&nbsp;substantial groundwater recharge occurs in an off-season period and/or at the beginning of growing season. Mulching was not proved to reduce evaporation. The best type of management providing for the economical water regime appears to be a&nbsp;one-cut variant. Relationships between botanical composition and GR water regime are also described.

REGRESSIONS FOR ESTIMATING STRAW YIELDS AND N AND P CONTENTS OF SPRING WHEAT AND N MINERALIZATION IN A BROWN LOAM SOIL

1988 ◽  
Vol 68 (2) ◽  
pp. 337-344 ◽  
Author(s):  
C. A. CAMPBELL ◽  
R. P. ZENTNER ◽  
F. SELLES
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Spring Wheat ◽  
N Mineralization ◽  
Soil Moisture Content ◽  
N Uptake ◽  
Growing Season ◽  
Net N Mineralization ◽  
Loam Soil ◽  
Growing Season Precipitation

Data from an 18-yr crop rotation study carried out on a Brown loam soil at Swift Current, Saskatchewan, were used to estimate equations that relate spring wheat straw yields, and N and P content of grain and straw to moisture use (MU). Moisture use was defined as soil moisture content in 0- to 120-cm depth at seeding, less soil moisture content at harvest, plus growing season precipitation. Grain yields were also related to straw yields and to N content of the straw. Potential net N mineralization (Nmin) in summerfallow (periods during the growing season with negative Nmin omitted) was related (r = 0.74**) to precipitation received during the spring to fall period. An attempt to relate apparent net Nmin (determined by N balance) in cropped systems to growing season precipitation or to MU was not successful. Highly significant linear regressions were obtained for straw yields, grain N and P contents vs. MU, and for grain yield vs. straw yield (r = 0.66** – 0.83**), but the other relationships were less reliable (r = 0.41** – 0.55**) though still significant. We discussed how these relationships might be used to estimate fertilizer N requirements, for examining N immobilization-mineralization, and for estimating residue sufficiency for erosion control on summerfallowed land. Key words: Straw:grain ratio, N uptake, P uptake, crop residues, N mineralization

scholarly journals WATER TABLE BEHAVIOR AND SOIL MOISTURE CONTENT DURING THE WINTER

1970 ◽  
Vol 50 (3) ◽  
pp. 361-366 ◽  
Author(s):  
J. C. van SCHAIK ◽  
E. RAPP
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Table ◽  
Soil Moisture Content ◽  
Growing Season ◽  
Grass Cover ◽  
Irrigation Project ◽  
Southern Alberta

Water table recession in an irrigation project in southern Alberta was compared with moisture translocation in covered lysimeters during two winters. Upward translocation to the surface 60 cm during one winter amounted to 1 to 2 cm of water in dry soils having a grass cover, and 2 to 2.3 cm in moist soils with no vegetation. Observations between growing season and freeze-up indicated that a considerable amount of water may drain downward. The upper 30 cm of soil generally is not influenced by upward translocation if the soil is dry before freeze-up.

scholarly journals Reusing Grey Water to Lower Temperatures in the Mediterranean Basin Cities

Earth ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 72-75
Author(s):  
Giuseppe Maggiotto
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Moisture Content ◽  
Air Temperature ◽  
Mediterranean Basin ◽  
Soil Moisture Content ◽  
Hot Spot ◽  
Grey Water ◽  
The Mediterranean ◽  
The Mediterranean Basin

The Mediterranean region is a hot spot for climate change, and cities of this area will be exposed to both increasing temperatures and decreasing precipitations. Green Infrastructures (GIs) can lower urban temperatures through evapotranspiration with an adequate soil moisture content. Grey water reuse can both guarantee the right soil moisture content and reduce freshwater exploitation. In order to test the effectiveness of soil moisture on reducing air temperature, two modelling simulations ran with the microclimate CFD-based model ENVI-met 4.0. The chosen day was a registered heat wave (7 July 2019) in Lecce, a city of south Italy, which was selected as case study for the Mediterranean area. The results demonstrated the effectiveness of soil moisture on evapotranspiration in reducing air temperature. From a circular economy perspective, the supply of grey water for urban GIs represents a strategic adaptation strategy to the expected effects of climate change on the Mediterranean basin.

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