scholarly journals Visual drainage assessment: A standardised visual soil assessment method for use in land drainage design in Ireland

2016 ◽  
Vol 55 (1) ◽  
pp. 24-35 ◽  
Author(s):  
P. Tuohy ◽  
J. Humphreys ◽  
N.M. Holden ◽  
J. O’Loughlin ◽  
B. Reidy ◽  
...  
Keyword(s):  
Water Table ◽  
Discharge Capacity ◽  
Drainage System ◽  
Assessment Method ◽  
Site Specific ◽  
Soil Assessment ◽  
Land Drainage ◽  
Standard Design ◽  
Rainfall Recharge ◽  
A Site

AbstractThe implementation of site-specific land drainage system designs is usually disregarded by landowners in favour of locally established ‘standard practice’ land drainage designs. This is due to a number of factors such as a limited understanding of soil–water interactions, lack of facilities for the measurement of soil’s physical or hydrological parameters and perceived time wastage and high costs. Hence there is a need for a site-specific drainage system design methodology that does not rely on inaccessible, time-consuming and/or expensive measurements of soil physical or hydrological properties. This requires a standardised process for deciphering the drainage characteristics of a given soil in the field. As an initial step, a new visual soil assessment method, referred to as visual drainage assessment (VDA), is presented whereby an approximation of the permeability of specific soil horizons is made using seven indicators (water seepage, pan layers, texture, porosity, consistence, stone content and root development) to provide a basis for the design of a site-specific drainage system. Across six poorly drained sites (1.3 ha to 2.6 ha in size) in south-west Ireland a VDA-based design was compared with (i) an ideal design (utilising soil physical measurements to elucidate soil hydraulic parameters) and (ii) a standard design (0.8 m deep drains at a 15 m spacing) by model estimate of water table control and rainfall recharge/drain discharge capacity. The VDA method, unlike standard design equivalents, provided a good approximation of an ideal (from measured hydrological properties) design and prescribed an equivalent land drainage system in the field. Mean modelled rainfall recharge/drain discharge capacity for the VDA (13.3 mm/day) and ideal (12.0 mm/day) designs were significantly higher (P< 0.001, s.e. 1.42 mm/day) than for the standard designs (0.5 mm/day), when assuming a design minimum water table depth of 0.45 m.

scholarly journals CO<sub>2</sub> fluxes and ecosystem dynamics at five European treeless peatlands – merging data and process oriented modeling

2015 ◽  
Vol 12 (1) ◽  
pp. 125-146 ◽  
Author(s):  
C. Metzger ◽  
P.-E. Jansson ◽  
A. Lohila ◽  
M. Aurela ◽  
T. Eickenscheidt ◽  
...  
Keyword(s):  
Water Table ◽  
Photosynthetic Efficiency ◽  
Heterotrophic Respiration ◽  
Soil Conditions ◽  
Model Parameters ◽  
Co2 Fluxes ◽  
Site Specific ◽  
Process Oriented ◽  
A Site ◽  
Organic Decomposition

Abstract. The carbon dioxide (CO2) exchange of five different peatland systems across Europe with a wide gradient in land use intensity, water table depth, soil fertility and climate was simulated with the process oriented CoupModel. The aim of the study was to find out whether CO2 fluxes, measured at different sites, can be explained by common processes and parameters or to what extend a site specific configuration is needed. The model was calibrated to fit measured CO2 fluxes, soil temperature, snow depth and leaf area index (LAI) and resulting differences in model parameters were analyzed. Finding site independent model parameters would mean that differences in the measured fluxes could be explained solely by model input data: water table, meteorological data, management and soil inventory data. Seasonal variability in the major fluxes was well captured, when a site independent configuration was utilized for most of the parameters. Parameters that differed between sites included the rate of soil organic decomposition, photosynthetic efficiency, and regulation of the mobile carbon (C) pool from senescence to shooting in the next year. The largest difference between sites was the rate coefficient for heterotrophic respiration. Setting it to a common value would lead to underestimation of mean total respiration by a factor of 2.8 up to an overestimation by a factor of 4. Despite testing a wide range of different responses to soil water and temperature, rate coefficients for heterotrophic respiration were consistently the lowest on formerly drained sites and the highest on the managed sites. Substrate decomposability, pH and vegetation characteristics are possible explanations for the differences in decomposition rates. Specific parameter values for the timing of plant shooting and senescence, the photosynthesis response to temperature, litter fall and plant respiration rates, leaf morphology and allocation fractions of new assimilates, were not needed, even though the gradient in site latitude ranged from 48° N (southern Germany) to 68° N (northern Finland) differed largely in their vegetation. This was also true for common parameters defining the moisture and temperature response for decomposition, leading to the conclusion that a site specific interpretation of these processes is not necessary. In contrast, the rate of soil organic decomposition, photosynthetic efficiency, and the regulation of the mobile carbon pool need to be estimated from available information on specific soil conditions, vegetation and management of the ecosystems, to be able to describe CO2 fluxes under different conditions.

scholarly journals Field Adaptation for Watermelon Cultivation under Shallow Ground Water Table in Tidal Lowland Reclamation Area

2020 ◽  
Vol 8 (1) ◽  
pp. 1
Author(s):  
Momon Sodik Imanudin ◽  
Satria JP ◽  
Bakri , ◽  
M. Edi Armanto
Keyword(s):  
Water Table ◽  
Agricultural Land ◽  
Water Status ◽  
Drainage System ◽  
Channel Depth ◽  
Gate Operation ◽  
Land Drainage ◽  
Wet Condition ◽  
Reclamation Area ◽  
Main Factor

<p> </p><ul><li>Agriculture productivity of tidal lowland reclamation areas in South Sumatra is still low. It leads to the increasing of agricultural land conversion into plantation areas. Controlling the water table is the main factor in the tidal lowlands; this research aimed to develop micro drainage system in tertiary block for controlling water table under wet condition. Watermelon was used as a crop indicator and planted in mid- March 2015. The location of the research was in a tidal lowland agriculture with land typology B, where the tide can only be as irrigation during the rainy season. The method of this research was surveying and monitoring. Groundwater observation, measurement value hydraulic conductivity and land drainage applications were included in the field activities. The design of land drainage used an<strong> </strong>intensive shallow drainage concept; the effect of the depth of the water table to water status was evaluated by the UPFLOW model. A micro drainage on tertiary block was used by 8 m drain spacing, with channel depth of 20 cm. The results showed that the tertiary gate operation was maximum drainage option. The water table depth was 25 cm in soil depth.The watermelon crops grew well and production reached 20 t ha-1</li></ul><pre>.  </pre><p> </p>

scholarly journals Functional expression of a yeast mitochondrial intron-encoded protein requires RNA processing at a conserved dodecamer sequence at the 3' end of the gene.

1989 ◽  
Vol 9 (4) ◽  
pp. 1507-1512 ◽  
Author(s):  
H Zhu ◽  
H Conrad-Webb ◽  
X S Liao ◽  
P S Perlman ◽  
R A Butow
Keyword(s):  
Genetic Analysis ◽  
Rna Processing ◽  
Fold Increase ◽  
Functional Expression ◽  
Rrna Gene ◽  
Yeast Mitochondria ◽  
Wild Type ◽  
Site Specific ◽  
Var1 Gene ◽  
A Site

All mRNAs of yeast mitochondria are processed at their 3' ends within a conserved dodecamer sequence, 5'-AAUAAUAUUCUU-3'. A dominant nuclear suppressor, SUV3-I, was previously isolated because it suppresses a dodecamer deletion at the 3' end of the var1 gene. We have tested the effects of SUV3-1 on a mutant containing two adjacent transversions within a dodecamer at the 3' end of fit1, a gene located within the 1,143-base-pair intron of the 21S rRNA gene, whose product is a site-specific endonuclease required in crosses for the quantitative transmission of that intron to 21S alleles that lack it. The fit1 dodecamer mutations blocked both intron transmission and dodecamer cleavage, neither of which was suppressed by SUV3-1 when present in heterozygous or homozygous configurations. Unexpectedly, we found that SUV3-1 completely blocked cleavage of the wild-type fit1 dodecamer and, in SUV3-1 homozygous crosses, intron conversion. In addition, SUV3-1 resulted in at least a 40-fold increase in the amount of excised intron accumulated. Genetic analysis showed that these phenotypes resulted from the same mutation. We conclude that cleavage of a wild-type dodecamer sequence at the 3' end of the fit1 gene is essential for fit1 expression.

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