scholarly journals Experimental and numerical investigation of laboratory scale sheetpipe-typed automatic subsurface irrigation

2021 ◽  
Vol 6 (2) ◽  
pp. 117-124
Author(s):  
Satyanto Krido Saptomo ◽  
Rudiyanto ◽  
Muhamad Askari ◽  
Chusnul Arif ◽  
Willy Bayuardi Suwarno ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Table ◽  
Soil Surface ◽  
Surface Irrigation ◽  
Soil Pressure ◽  
Variable Head ◽  
Irrigation Control ◽  
Soil Wetting ◽  
Perforated Pipe ◽  
Water Table Control

Sheet pipe is a type of perforated pipe used for drainage designed initially for drainage but has the potential for sub-surface irrigation. The objectives of this study were to experiment and observe the performance of the sub-surface irrigation control system with sheet pipe. This investigation covered the observation of water table control and its effect on soil moisture. The detailed process of water flow during the setting of the water table was numerically modeled in 2 dimensions to observe the distribution of soil moisture, soil pressure, and flux. The results showed that the system successfully controlled the water table at the desired level in the experiment. The developed two-dimensional numerical simulation showed the distribution of soil moisture in the model center as a response to the water table increase, represented by the variable head. The soil wetting advances toward soil surface driven by the water table, which was increased gradually and reached saturation at the height of water table setpoint.

Dissolved Phosphorus Losses in Tile Drainage under Subirrigation

2006 ◽  
Vol 41 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Nicolas Stämpfli ◽  
Chandra A. Madramootoo
Keyword(s):  
Water Table ◽  
Residual Effect ◽  
Surface Water Quality ◽  
Soil Surface ◽  
Quality Standard ◽  
Tile Drainage ◽  
Agricultural Field ◽  
Shallow Water Table ◽  
Dissolved Phosphorus ◽  
Water Table Control

Abstract Recent studies have shown subirrigation (SI) to be effective in reducing nitrate losses from agricultural tile drainage systems. A field study was conducted from 2001 to 2002 in southwestern Québec to evaluate the effect of SI on total dissolved phosphorus (TDP) losses in tile drainage. In an agricultural field with drains installed at a 1-m depth, a SI system with a design water table depth (WTD) of 0.6 m below the soil surface was compared with conventional free drainage (FD). Subirrigation increased drainage outflow volumes in the autumn, when drains were opened and water table control was interrupted for the winter in the SI plots. Outflows were otherwise similar for both treatments. Throughout the study, the TDP concentrations in tile drainage were significantly higher with SI than with FD for seven out of 17 of the sampling dates for which data could be analyzed statistically, and they were never found to be lower for plots under SI than for plots under FD. Of the seven dates for which the increase was significant, six fell in the period during which water table control was not implemented (27 September 2001 to 24 June 2002). Hence, it appears that SI tended to increase TDP concentrations compared with FD, and that it also had a residual effect between growing seasons. Almost one-third of all samples from the plots under SI exceeded Québec's surface water quality standard (0.03 mg TDP L-1), whereas concentrations in plots under FD were all below the standard. Possible causes of the increase in TDP concentrations in tile drainage with SI are high TDP concentrations found in the well water used for SI and a higher P solubility caused by the shallow water table.

scholarly journals Mapping the Pollution Plume Using the Self-Potential Geophysical Method: Case of Oum Azza Landfill, Rabat, Morocco

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 961
Author(s):  
Meryem Touzani ◽  
Ismail Mohsine ◽  
Jamila Ouardi ◽  
Ilias Kacimi ◽  
Moad Morarech ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Water Table ◽  
Soil Surface ◽  
The Self ◽  
Drainage Network ◽  
Geophysical Method ◽  
Direct Measurements ◽  
Sandy Material ◽  
The City ◽  
Self Potential

The main landfill in the city of Rabat (Morocco) is based on sandy material containing the shallow Mio-Pliocene aquifer. The presence of a pollution plume is likely, but its extent is not known. Measurements of spontaneous potential (SP) from the soil surface were cross-referenced with direct measurements of the water table and leachates (pH, redox potential, electrical conductivity) according to the available accesses, as well as with an analysis of the landscape and the water table flows. With a few precautions during data acquisition on this resistive terrain, the results made it possible to separate the electrokinetic (~30%) and electrochemical (~70%) components responsible for the range of potentials observed (70 mV). The plume is detected in the hydrogeological downstream of the discharge, but is captured by the natural drainage network and does not extend further under the hills.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

Response of winter wheat to prolonged waterlogging under outdoor conditions

1981 ◽  
Vol 97 (3) ◽  
pp. 557-568 ◽  
Author(s):  
R. K. Belford
Keyword(s):  
Winter Wheat ◽  
Water Table ◽  
Stem Elongation ◽  
Soil Surface ◽  
Root Production ◽  
Or Efficiency ◽  
Plant Nitrogen ◽  
Stages Of Growth ◽  
Nodal Root ◽  
Waterlogging Treatment

SUMMARYThe response of winter wheat cv. Maris Huntsman to waterlogging was studied in two experiments in soil columns outdoors. Winter waterlogging treatments increased nodal root production and the proportion of aerenchyma within roots, but caused chlorosis and premature senescence of leaves, and decreased tillering. For all treatments, grain losses were much less than expected from the extent of tiller loss in winter; losses after single waterlogging events ranged from 2% (after 47 days with the water-table at 5 cm) to 16% (after 80 days with the water-table at the soil surface). Yield losses after three waterloggings at the seedling, tillering and stem elongation stages of growth were additive, and totalled 19%. In many treatments, grain loss was associated with lighter individual grain weights, suggesting that the size of the root system or efficiency of water and nutrient uptake by roots at the later stages of growth may have been less after earlier waterlogging. The importance of nitrogen fertilizer in maintaining a satisfactory plant nitrogen status was shown when nitrogen was with held before a 3-week waterlogging treatment during stem elongation; tiller and floret survival was subsequently greatly restricted and grain yields decreased 22% below those of plants waterlogged at the same stage of growth but supplied with nitrogen.

Biology and natural history of Caladenia

2009 ◽  
Vol 57 (4) ◽  
pp. 247 ◽  
Author(s):  
Kingsley Dixon ◽  
Raymond L. Tremblay
Keyword(s):  
Natural History ◽  
Arid Zone ◽  
Secondary Infection ◽  
Soil Surface ◽  
Growth Cycle ◽  
Cortical Cells ◽  
Herbaceous Perennials ◽  
Terrestrial Orchids ◽  
History Of ◽  
Soil Wetting

The genus Caladenia comprises species that exhibit remarkable consistency in terms of growth form and phenological patterns. All taxa are herbaceous perennials, with the shoot arising annually from a single, usually spheroid, tuber and producing a single, hairy leaf. The tuber is annually replaced either side-by-side with the parent tuber or terminating a descending structure known as a dropper. The dropper is a depth-seeking mechanism that enables placement of the tuber at depth in the soil as a means to avoid predation by surface-foraging native mammals or away from the high temperatures and desiccating conditions during summer dormancy. The 3--5 attenuated roots produced at the junction between the tuber and shoot and produced late in the growing cycle and devoid of mycorrhiza suggest their functional significance may relate to water uptake. Mycorrhizal endophytes are confined to a hypertrophic stem region at the soil surface (collar) subtending the leaf that positions the collar directly in the organically rich zone at the soil surface. This morphology is a unique characteristic of several Australasian orchids in the tribe Diuridae. Mycorrhizal infection occurs rapidly, with maximum colonisation in concert with the onset of breaking rains. Pelotons are restricted to cortical cells, with fully developed pelotons throughout infected tissues within a week or so of soil wetting. Infection occurs as a ‘once-off’ event, with little evidence of secondary infection later in the growth cycle and no evidence of peloton digestion. Some taxa utilise vegetative propagation, often leading to localised clustering as for taxa in the ‘filamentosa’ complex or, extensive clonal mats as found in Caladenia flava and C. latifolia where daughter tubers are produced at the end of extending horizontal outgrowths. For the majority of taxa, plants remain dry-season (summer) dormant from a few months up to 7 months for arid-zone taxa, with shoot emergence from the tuber of temperate species thought to occur in response to a drop in the mean minimum temperature. Pollination biology of Caladenia is apparently through a process of deception, either as food or sexual mimics, with some taxa engaging in self-pollination. Here we review the natural history of Caladenia and acknowledge that much of our understanding is based on assumptions of the biology of terrestrial orchids in general and emphasise areas of research and biological enquiry that will be critical in the development of an effective conservation program for the genus.

scholarly journals Coupled stochastic dynamics of water table and soil moisture in bare soil conditions

2008 ◽  
Vol 44 (1) ◽  
Author(s):  
L. Ridolfi ◽  
P. D'Odorico ◽  
F. Laio ◽  
S. Tamea ◽  
I. Rodriguez-Iturbe
Keyword(s):  
Soil Moisture ◽  
Water Table ◽  
Stochastic Dynamics ◽  
Bare Soil ◽  
Soil Conditions

scholarly journals Potential Applications of GNSS-R Observations over Agricultural Areas: Results from the GLORI Airborne Campaign

2018 ◽  
Vol 10 (8) ◽  
pp. 1245 ◽  
Author(s):  
Mehrez Zribi ◽  
Erwan Motte ◽  
Nicolas Baghdadi ◽  
Frédéric Baup ◽  
Sylvia Dayau ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Signal To Noise Ratio ◽  
Soil Surface ◽  
Satellite System ◽  
Area Index ◽  
Vegetation Height ◽  
Study Sites ◽  
Global Navigation Satellite ◽  
Vegetation Characteristic ◽  
Agricultural Areas

The aim of this study is to analyze the sensitivity of airborne Global Navigation Satellite System Reflectometry (GNSS-R) on soil surface and vegetation cover characteristics in agricultural areas. Airborne polarimetric GNSS-R data were acquired in the context of the GLORI’2015 campaign over two study sites in Southwest France in June and July of 2015. Ground measurements of soil surface parameters (moisture content) and vegetation characteristics (leaf area index (LAI), and vegetation height) were recorded for different types of crops (corn, sunflower, wheat, soybean, vegetable) simultaneously with the airborne GNSS-R measurements. Three GNSS-R observables (apparent reflectivity, the reflected signal-to-noise-ratio (SNR), and the polarimetric ratio (PR)) were found to be well correlated with soil moisture and a major vegetation characteristic (LAI). A tau-omega model was used to explain the dependence of the GNSS-R reflectivity on both the soil moisture and vegetation parameters.

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