Anthropogenic impact on inorganic soil C: Impact of Irrigated Agriculture on Carbonates Dynamics in Semiarid Land

2020 ◽  
Author(s):  
Isabel S. De Soto ◽  
Iñigo Virto ◽  
Alberto Enrique ◽  
Rodrigo Antón ◽  
Pierre Barré
Keyword(s):  
Numerical Simulations ◽  
Size Distribution ◽  
Soil Solution ◽  
Irrigation Water ◽  
Carbonate Dissolution ◽  
Field Observations ◽  
Experimental Plot ◽  
Pedogenic Carbonates ◽  
Mediterranean Soils ◽  
Precipitation Cycles

<p>In many semiarid Mediterranean soils, carbonates can constitute a significant proportion of the soil mass. Unlike other soil inorganic components, carbonates can react in the short term to changes in the soil water regime and the physical-chemical conditions of the soil solution. The introduction of irrigation can be associated to such changes, as it changes the water balance, the composition of the soil solution, and the concentration of CO<sub>2</sub> in the soil atmosphere.</p><p>To gain knowledge on the importance of the effect of irrigation on carbonates dynamics in the tilled layer of agricultural Mediterranean soils, we conducted a three-step study embracing field observations and numerical simulation.</p><p>In the first step, carbonates stocks and size-distribution were quantified for two different situations (irrigation and non-irrigation) in paired plots of three irrigation districts in Navarre (Spain). Our results, showed that although the net annual balance of total carbonates-C between irrigated and non-irrigated plots was neutral, carbonates concentration was lower with irrigation in the finest (< 50 μm) soil fractions (25.6 ± 2.6 carbonates 100 g<sup>−1</sup> without irrigation for 19.3 ± 2.1 with irrigation, on average).</p><p>In a second step, numerical simulations of the geochemical interactions between soil carbonates, the soil solution and irrigation water were run using actual soil characteristics and soil solution data from the tilled layer (0-30 cm) of two paired plots 9 years after irrigation started. A sensitivity analysis was also conducted to investigate the potential impact of water quality and crop types as sources of variability in the model outputs. The modelling results showed annual losses of carbonates-C in the range of 12.06-13.52 g m<sup>−2</sup> year<sup>−1</sup> in the studied depth under irrigation, depending on the quality of irrigation water, for 0.46 g m<sup>−2</sup> without irrigation.</p><p>Lastly, and because the acceleration of carbonate dissolution/precipitation cycles, together with the addition of calcium in fertilizers and irrigation water, can cause an increase in the formation of pedogenic carbonates, their proportion was estimated in paired plots from carbonates-C isotopic signatures: a preferential accumulation of pedogenic carbonates in the finest size fractions (87-92%) was observed with irrigation (61-74% without irrigation).</p><p><em>Future investigations</em></p><p>New field observations and numerical simulations will be done in an experimental plot in  which corn (Zea mays L.) has been grown since 2010 with and without irrigation. A numerical model will be developed to study the expected changes in the carbonate dissolution/precipitation cycles in semi-arid Mediterranean areas and these results will be compared with the concentration and characteristics of carbonates (size distribution and isotopic signature as an indicator of their geological or pedogenic origin) in the experimental plot.</p><p>Finally, the model will be validated at a regional scale, using a network of real representative agricultural plots in which there has been a change in land use from unirrigated to irrigated land in Navarre.</p><p> </p>

Trapping patterns during capillary displacements in disordered media

2022 ◽  
Vol 933 ◽  
Author(s):  
Fanli Liu ◽  
Moran Wang
Keyword(s):  
Numerical Simulations ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Disordered Media ◽  
Pore Geometry ◽  
Control Parameters ◽  
Pore Throat ◽  
The Impact ◽  
Theoretical Analyses

We investigate the impact of wettability distribution, pore size distribution and pore geometry on the statistical behaviour of trapping in pore-throat networks during capillary displacement. Through theoretical analyses and numerical simulations, we propose and prove that the trapping patterns, defined as the percentage and distribution of trapped elements, are determined by four dimensionless control parameters. The range of all possible trapping patterns and how the patterns are dependent on the four parameters are obtained. The results help us to understand the impact of wettability and structure on trapping behaviour in disordered media.

scholarly journals Concentration of injetion solution and its effects on soil and on yield of fertirrigated banana cv. Terra Maranhão

2014 ◽  
Vol 34 (6) ◽  
pp. 1104-1113 ◽  
Author(s):  
Eugênio F. Coelho ◽  
Torquato M. de Andrade Neto ◽  
Damiana L. Barros
Keyword(s):  
Electrical Conductivity ◽  
Soil Solution ◽  
Irrigation Water ◽  
Urea Concentration ◽  
Injection Solution ◽  
Combined Application ◽  
Saturation Extract ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Micro Irrigation

The Fertigation is the combined application of water and nutrients to a crop. It can be adapted to all types of agricultural crops. The objective of this study was to evaluate the effect of urea concentration in irrigation water on electrical conductivity of the soil solution and saturation extract along the first cycle of banana cv. Terra Maranhão. The experiment followed a completely randomized design with six treatments and ten replications. Treatments regarded for using three urea concentrations (1.0; 2.5 and 4.0 g L-1) in irrigation water applied by two micro irrigation systems (microsprinkler and drip). Results showed that there was a linear elevation of electrical conductivity of saturation extract and soil solution with the increase on concentration of urea in the injection solution. Urea should be used under concentrations up to 2.5 g L-1 in irrigation water without causing increase on electric conductivity of soil solution and saturation extract, considering 1.1 dS m-1 as the tolerated value for the crop. Nitrate in the soil solution increased significantly with the increase of urea concentration in the injection solution. The maximum concentration of nitrate in the soil occurred for 4,0 g L-1 concentration of the injection solution.

scholarly journals Using Soil Solution Monitoring to Determine the Effects of Irrigation Management and Fertigation on Nitrogen Availability in High-density Apple Orchards

1998 ◽  
Vol 123 (4) ◽  
pp. 706-713 ◽  
Author(s):  
D. Neilsen ◽  
P. Parchomchuk ◽  
G.H. Neilsen ◽  
E.J. Hogue
Keyword(s):  
Soil Solution ◽  
Irrigation Water ◽  
Root Zone ◽  
Irrigation Management ◽  
Sprinkler Irrigation ◽  
Loamy Sand ◽  
N Availability ◽  
Silt Loam ◽  
N Concentration ◽  
Loam Soil

Direct application of fertilizers in irrigation water (fertigation) is an efficient method of supplying nutrients to fruit trees. Information is needed on the relationship between irrigation and N inputs on N availability in order to target nutrient applications to meet plant demands. Soil solution was collected from permanently installed suction lysimeters and NO3-N concentration was measured over the growing season in three experiments: 1) comparison of sprinkler irrigation + broadcast fertilizer with weekly fertigation + daily drip irrigation; 2) comparison of (NH4)2SO4 or Ca(NO3)2 as N sources under daily fertigation; and 3) comparisons of combinations of irrigation applied at either fixed rates or to meet evaporative demand and fertilizer (Ca(NO3)2) applied daily either at fixed rates or to maintain a given concentration in the fertigation solution in two soil types—loamy sand and silt loam. Trials are located in high density apple plantings of either `Gala' or `Empire' apple (Malus × domestica Borkh.) on M.9 rootstock. Nitrate-N concentration in the soil solution measured at 30 cm deep remained higher, over more of the growing season, for weekly fertigation + daily drip irrigation than for a single broadcast fertilizer application + sprinkler irrigation. With daily Ca(NO3)2 fertigation, soil solution NO3- N concentrations increased and decreased rapidly with the onset and end of fertigation respectively, remained relatively constant during the intervening period and were directly proportional to either the amount of N or the amount of irrigation water added. Daily fertigation with (NH4)2SO4 resulted in less control of NO3-N availability in the root-zone than with Ca(NO3)2, which may be problematic for precise timing of N nutrition. Except for the fixed irrigation rate applied to the loamy sand soil, soil solution NO3-N concentrations at 30 cm beneath the emitter were similar to average concentrations in the fertigating solution, for all methods of irrigation management in both soil types. Elevated NO3-N concentrations in soil solution below the root zone (75 cm deep) were detected in the loamy sand regardless of methods of N application and irrigation although there was some evidence of less leaching to this depth, under scheduled irrigation. In the silt loam soil, considerably lower concentrations of NO3-N were found beneath the root zone than at 30 cm deep for all of irrigation procedures and frequently there was insufficient water moving to 75 cm to provide sample. Tree growth in the loamy sand was less than in the silt loam soil; was limited by low application of irrigation water in 1992 and 1993; was unaffected by NO3-N concentration in the root zone, indicating that N inputs could be minimized by adding N to maintain concentrations of 75 μg·mL-1 or possibly less. Nitrogen inputs may also be reduced if fertilizer N and irrigation water could be retained within the root zone. For coarse-textured soils this will require precise additions of water and possibly soil amendments to improve water holding capacity.

scholarly journals The origin of comets among the accreting outer planets

1985 ◽  
Vol 83 ◽  
pp. 3-10
Author(s):  
Richard Greenberg
Keyword(s):  
Numerical Simulations ◽  
Size Distribution ◽  
Power Law ◽  
Building Blocks ◽  
Oort Cloud ◽  
Reasonable Time ◽  
Outer Planets ◽  
Building Process ◽  
History Of

AbstractThe hypothesis of formation of comets as an accompaniment to formation of Uranus and Neptune from icy planetesimals is attractive for several reasons, but has suffered from long-standing problems regarding formation of the planets themselves. The history of this problem is reviewed, and recent results are described that may help solve it. Numerical simulations of planet growth show that when the system of planetesimals is no longer artificially constrained to a power-law size distribution, growth of planets may occur in reasonable time. An adeguate number of comet-sized bodies to populate the Oort cloud is not produced as collisional debris during the planet-building process. Rather, the comets are probably a remnant of the original planetesimal “building blocks” from which the planets grew.

The Storegga Slide tsunami—comparing field observations with numerical simulations

2005 ◽  
Vol 22 (1-2) ◽  
pp. 195-208 ◽  
Author(s):  
Stein Bondevik ◽  
Finn Løvholt ◽  
Carl Harbitz ◽  
Jan Mangerud ◽  
Alastair Dawson ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Field Observations ◽  
Storegga Slide

scholarly journals SHORELINE ROTATION CAUSED BY LARGE-SCALE EXCAVATION OF REEF FLAT ON SANUR BEACH IN BALI

2011 ◽  
Vol 1 (32) ◽  
pp. 93
Author(s):  
Masatoshi Endo ◽  
Akio Kobayashi ◽  
Takaaki Uda ◽  
Yasuhito Noshi ◽  
Susumu Onaka
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Reef Flat ◽  
Beach Nourishment ◽  
Beach Erosion ◽  
Field Observations ◽  
Wave Direction ◽  
Bathymetric Survey ◽  
Shoreline Changes ◽  
S Model

In the southern part of Sanur Beach in Bali, beach erosion has occurred between groins after extensive beach nourishment, resulting in shoreline rotation between the groins. The cause of shoreline changes was investigated by field observations, including a bathymetric survey and the sampling of seabed materials, and numerical simulations of beach changes were carried out using Noshi et al.’s model. It was concluded that the shoreline rotation was triggered by the dredging of the reef flat, which caused a change in the wave direction on the reef flat due to the diffraction of waves.

scholarly journals Numerical simulations of homogeneous freezing processes in the aerosol chamber AIDA

2002 ◽  
Vol 2 (5) ◽  
pp. 1467-1508
Author(s):  
W. Haag ◽  
B. Kärcher ◽  
S. Schaefers ◽  
O. Stetzer ◽  
O. Möhler ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Size Distribution ◽  
Time History ◽  
Companion Paper ◽  
Aerosol Size Distribution ◽  
Size Spectrum ◽  
Mixing Ratio ◽  
Atmospheric Conditions ◽  
Aerosol Chamber ◽  
Homogeneous Freezing

Abstract. The homogeneous freezing of supercooled H2SO4/H2O aerosols in an aerosol chamber is investigated with a microphysical box model using the activity parameterization of the nucleation rate by Koop et al (2000). The simulations are constrained by measurements of pressure, temperature, total water mixing ratio, and the initial aerosol size distribution, described in a companion paper Möhler et al. (2002). Model results are compared to measurements conducted in the temperature range between 194 and 235 K, with cooling rates in the range between 0.5 and 2.6 K min-1, and at air pressures between 170 and 1000 hPa. The simulations focus on the time history of relative humidity with respect to ice, aerosol size distribution, partitioning of water between gas and particle phase, onset times of freezing, freezing threshold relative humidities, aerosol chemical composition at the onset of freezing, and the number of nucleated ice crystals. The latter three parameters can directly be inferred from the experiments, the former three aid in interpreting the measurements. Sensitivity studies are carried out to address the relative importance of uncertainties of basic quantities such as temperature, H2O mixing ratio, aerosol size spectrum, and deposition coefficient of H2O molecules on ice. The ability of the numerical simulations to provide detailed explanations of the observations greatly increases confidence in attempts to model this process under real  atmospheric conditions, for instance with regard to the formation of cirrus clouds or type-II polar stratospheric clouds, provided that accurate temperature and humidity measurements are available.

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