The interactive effects of increased evaporative demand and soil water on photosynthesis in maize

1991 ◽  
Vol 71 (1) ◽  
pp. 31-39 ◽  
Author(s):  
R. G. Berard ◽  
G. W. Thurtell
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Soil Moisture Content ◽  
Water Status ◽  
Interactive Effects ◽  
Evaporative Demand ◽  
Photosynthetic Rates ◽  
Root Medium ◽  
Wide Range

A field-portable whole-plant enclosure system was used to study the effect of increased evaporative demand on photosynthetic rates of maize (Zea mays L.) subjected to various root medium treatments. The system consisted of two transparent chambers, each capable of maintaining a fully grown maize plant at ambient conditions while enabling different evaporative demand treatments by controlling the humidity. The rooting media consisted of silt loam soil held at three levels of soil moisture content covering a wide range of available moisture, and a hydroponic medium consisting of 25-L pails containing "Turface" and supplied three times daily with a nutrient solution. Measurements were carried out during the post-silking period from 22 July to 6 Sept. 1987 and consisted of at least 4 d of continuous monitoring of photosynthesis and transpiration rates from early morning till sundown. The effect of increased evaporative demand on photo-synthetic rates was relatively small, with average photosynthetic reductions of approximately 4–6% in all root medium treatments. Soil moisture content did not have any effect on the reduction of photosynthesis which occurred at high evaporative demand. However, absolute photosynthetic rates were significantly reduced by low soil moisture. It is suggested that atmospheric conditions leading to high transpiration rates are much less important than soil moisture conditions in causing yield reductions due to reduced photosynthetic rates. The results support recent evidence by other workers that soil water status can influence stomatal conductance and photosynthesis without the intermediary influence of leaf water status. Key words: Photosynthesis, transpiration, maize, soil water content, VPD, leaf conductance

scholarly journals Prediction Models for the Estimation of Soil Moisture Content

2011 ◽  
Author(s):  
Swathi Gorthi ◽  
Huifang Dou
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Prediction Models ◽  
Recursive Partitioning ◽  
Machine Learning Techniques ◽  
Linear Regression Models ◽  
Remotely Sensed Data ◽  
Modeling Tools ◽  
Wide Range

This paper provides a survey on different kinds of prediction models developed for the estimation of soil moisture content of an area, using empirical information including meteorological and remotely sensed data. The different models employed extend over a wide range of machine learning techniques starting from Basic Linear Regression models through models based on Bayesian framework, Decision tree learning and Recursive partitioning, to the modern non-linear statistical data modeling tools like Artificial Neural Networks. The fundamental mathematical backgrounds, pros and cons, prediction results and efficiencies of all the models are discussed.

scholarly journals Study on Variation of Surface Runoff and Soil Moisture Content in the Subgrade of Permeable Pavement Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lijun Hou ◽  
Yuan Wang ◽  
Fengchun Shen ◽  
Ming Lei ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Soil Moisture Content ◽  
Asphalt Pavement ◽  
Infiltration Rate ◽  
Runoff Coefficient ◽  
Flood Peak

The self-designed indoor simulated rainfall device was used to rain on five types of pavement structures with 4 types of rainfall intensity (2.5 mm/min, 3.4 mm/min, 4.6 mm/min, and 5.5 mm/min). The effect of rainfall intensity on the surface runoff, the relation between the subgrade soil moisture content changes, and the influence of initial soil water content on rain infiltration rate are studied. The test results show that the surface runoff coefficient of densely asphalted pavement is greater than 90% in drainage pavements and it has little influence on the reducing and hysteresis of the flood peak. The surface runoff coefficient of large-void asphalt pavement (permeable) is less than 40%. Although the large-void asphalt pavement (permeable) can reduce a small amount of surface runoff, it has no obvious effect on the reduction and hysteresis of the flood peak. In semipermeable pavement, with the increasing of the thickness of base (graded gravel), the surface runoff coefficient decreases at different rainfall intensities, parts of the surface runoff are reduced, and the arrival of flood peaks is delayed. In permeable roads, almost no surface runoff occurred. As time continued, the soil moisture content quickly reached a saturated state and presented a stable infiltration situation under the action of gravity and the gradient of soil water suction. As the initial moisture content increases, the initial infiltration rate decreases and the time to reach a stable infiltration rate becomes shorter. The drier the soil, the greater the initial infiltration rate and the higher the soil moisture content after infiltration stabilization. Permeable roads can greatly alleviate the pressure of urban drainage and reduce the risk of storms and floods.

scholarly journals The Influence of a Water Absorbing Geocomposite on Soil Water Retention and Soil Matric Potential

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1731 ◽  
Author(s):  
Michał Śpitalniak ◽  
Krzysztof Lejcuś ◽  
Jolanta Dąbrowska ◽  
Daniel Garlikowski ◽  
Adam Bogacz
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Water Retention ◽  
Soil Moisture Content ◽  
Soil Surface ◽  
Soil Matric Potential ◽  
Soil Water Retention ◽  
Matric Potential ◽  
Control Samples

Climate change induces droughts that are becoming more intensive and more frequent than ever before. Most of the available forecast tools predict a further significant increase in the risk of drought, which indicates the need to prepare solutions to mitigate its effects. Growing water scarcity is now one of the world’s leading challenges. In agriculture and environmental engineering, in order to increase soil water retention, soil additives are used. In this study, the influence of a newly developed water absorbing geocomposite (WAG) on soil water retention and soil matric potential was analyzed. WAG is a special element made from geotextile which is wrapped around a synthetic skeleton with a superabsorbent polymer placed inside. To describe WAG’s influence on soil water retention and soil matric potential, coarse sand, loamy sand, and sandy loam soils were used. WAG in the form of a mat was used in the study as a treatment. Three kinds of samples were prepared for every soil type. Control samples and samples with WAG treatment placed at depths of 10 cm and 20 cm were examined in a test container of 105 × 70 × 50 cm dimensions. The samples had been watered and drained, and afterwards, the soil surface was heated by lamps of 1100 W total power constantly for 72 h. Soil matric potential was measured by Irrometer field tensiometers at three depths. Soil moisture content was recorded at six depths: of 5, 9, 15, 19, 25, and 30 cm under the top of the soil surface with time-domain reflectometry (TDR) measurement devices. The values of soil moisture content and soil matric potential were collected in one-minute steps, and analyzed in 24-h-long time steps: 24, 48, and 72 h. The samples with the WAG treatment lost more water than the control samples. Similarly, lower soil matric potential was noted in the samples with the WAG than in the control samples. However, after taking into account the water retained in the WAG, it appeared that the samples with the WAG had more water easily available for plants than the control samples. It was found that the mechanism of a capillary barrier affected higher water loss from soil layers above those where the WAG had been placed. The obtained results of water loss depend on the soil type used in the profile.

Orthogonal Analysis on the Remediation of Diesel Contaminated Soil by Enhancing Bioventing

2013 ◽  
Vol 807-809 ◽  
pp. 178-183
Author(s):  
Jin Feng Yang ◽  
Cheng Jun Zhang ◽  
Tong Ke Zhao ◽  
Qiong Wu
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Contaminated Soil ◽  
Pore Volume ◽  
Soil Moisture Content ◽  
High Efficiency ◽  
Orthogonal Experiment ◽  
Volume Number ◽  
Soil Venting

Bioventing is an in situ forced oxidative soil remediation technology which combined soil vapor extraction with biodegradation. It has broad application prospects of soil contamination caused by underground storage tank leakage. Orthogonal experiment as a high efficiency, rapid and economical experimental design method has been widely used in many research. In order to enhance bioventing and shorten the cycle of pollution control,it is necessary to study the mechanism of the interaction among the different factors to quantify the interaction and accelerate the degradation rate. In this study, five factors (initial diesel concentration, venting mode, pore volume number during soil venting, soil moisture content and the ratio of carbon, nitrogen and phosphate) which influence bioventing was chosen to conduct orthogonal experiment of the remediation of diesel contaminated soil by enhancing bioventing. The results show that: 1)Initial diesel concentration and soil moisture content have main effects on the remediation of diesel contaminated soil by bioventing, then the ratio of carbon, nitrogen and phosphate and pore volume number during soil venting. Venting mode has the weakest effect. 2)When 40mg oil/g soil of diesel concentration, air injecting from the bottom of column, 4 vk·d-1 of the pore volume number during soil venting, 100:20:1 of the ratio of carbon, nitrogen and phosphate and soil water content for 20% of the maximum of soil water holding capacity, that would reach a larger removal rate.

Effects of Mulches on Soil Water Content and Water Status of Tea Plants in Kenya

1980 ◽  
Vol 16 (3) ◽  
pp. 295-302 ◽  
Author(s):  
C. O. Othieno
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Water Status ◽  
Different Types ◽  
Continuous Application ◽  
Black Plastic ◽  
Tea Plants ◽  
Water Holding ◽  
Better Than

SUMMARYSoil moisture content and plant water status of young clonal tea plants were affected differently by five different types of mulches (black plastic, stone chippings and three types of grass) when compared with a control without mulch. During prolonged droughts, soil moisture content was generally highest under Napier grass and black plastic but any type of mulch was better than no mulch in conserving moisture to 90 cm depth. Tensiometer data at the onset of rains after an unusual prolonged dry season suggest that the infiltration was fastest under grass mulches. After four years of continuous application grass mulches had significantly most effect on water holding capacity, but induced shallow rooting systems, which made the mulched tea more susceptible to drought.

Physiological and biochemical responses of Festuca sinensis seedlings to temperature and soil moisture stress

2017 ◽  
Vol 44 (10) ◽  
pp. 1007
Author(s):  
Jian-Jun Wang ◽  
Wei-Hu Lin ◽  
Yan-Ting Zhao ◽  
Cheng Meng ◽  
An-Wei Ma ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Moisture Content ◽  
Soluble Sugar ◽  
Free Proline ◽  
Relative Water ◽  
Physiological And Biochemical

The interaction effects between temperature and soil moisture on Festuca sinensis Keng ex E.B.Alexeev were analysed to determine how F. sinensis responds to these environmental conditions. A pot experiment was conducted in a greenhouse under simulated growth conditions with four soil moisture contents (80, 65, 50 and 35% relative saturation moisture content) and three temperature conditions (15, 20 and 25°C). Physiological (relative water content and root activity) and biochemical parameters (chlorophyll, peroxidase (POD), malondialdehyde (MDA), soluble protein, soluble sugar and free proline) were evaluated at the seedling stage. Results showed that with a decrease in soil water content, the POD activities, MDA content, soluble protein content, soluble sugar content and free proline content of plants under the 15°C and 20°C treatments initially decreased and then increased, whereas they increased with a decrease of soil water content at 25°C. The relative water contents of plants under the three temperature treatments decreased with a decreasing soil moisture content, but then increased temperature significantly reduced the relative water content of the seedlings under low soil water content. The chlorophyll contents of plants under the 25°C treatment decreased with a decrease of soil moisture content, but those of plants under the 15°C and 20°C treatments initially increased and then decreased. The root activities of plants under the 15°C and 20°C treatments increased with a decreasing soil moisture content; however, those of plants under the 25°C treatment initially increased and then decreased. Thus, results indicated that changes of temperature and soil moisture content had significant and complicated effects on the physiological-biochemical characteristics of F. sinensis; the conditions of 20°C and 65% RSMC had positive effects on F. sinensis seedling growth and the appropriate drought stress could promote the growth of seedling roots under the three different temperature conditions. In conclusion, F. sinensis seedlings could adapt to certain changes in the ecological environment by regulating their physiological and biochemical reactions.

scholarly journals Stomatal Conductance of Lysimeter-grown Asian Pear Trees before and during Soil Moisture Deficits

1994 ◽  
Vol 119 (6) ◽  
pp. 1261-1264 ◽  
Author(s):  
A. Richard Renquist ◽  
Horst W. Caspari ◽  
M. Hossein Behboudian ◽  
David J. Chalmers
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Water Deficit ◽  
Sap Flow ◽  
Water Status ◽  
Evaporative Demand ◽  
Pulse Technique ◽  
Asian Pear ◽  
Pear Trees

Stomatal conductance (gs) of `Hosui' Asian pear (Pyrus serotina Rehder) trees growing in lysimeters was characterized for trees in well-watered soil and after brief water deficit. The measures of water status used to interpret gs data were soil-water content, leaf water potential (ψl), and instantaneous water use (trunk sap flow by the compensation heat-pulse technique). The diurnal course and range of gs values of well-irrigated Asian pear trees were similar to those reported for other tree fruit crops. Soil moisture at the end of a midsummer deficit period was 60% of lysimeter pot capacity, and diurnal ψl reflected this deficit predawn and in the late afternoon compared to well-irrigated trees. The gs was sensitive to deficit irrigation during more of the day than ψl, with gs values <3 mm·s-1 for most of the day; these were less than half the conductances of well-irrigated trees. The reduction of gs in response to a given soil-water deficit was not as great on days with lower evaporative demand. After a water deficit, gs recovered to predeficit values only gradually over 2 to 3 days. The low gs of trees in dry soil was the apparent cause of reduced transpiration, measured by trunk sap flow, and reduced responsiveness of sap flow to fluctuations in net radiation.

Sign in / Sign up

Export Citation Format

Share Document