Nitrate leaching from a drained, sheep-grazed pasture. II. Modelling nitrate leaching losses

Soil Research ◽  
1998 ◽  
Vol 36 (6) ◽  
pp. 963 ◽  
Author(s):  
R. E. White ◽  
L. K. Heng ◽  
G. N. Magesan
Keyword(s):  
Nitrate Leaching ◽  
Preferential Flow ◽  
Pulse Input ◽  
Grazed Pasture ◽  
Sink Term ◽  
Chloride Leaching ◽  
Loam Soil ◽  
Rain Events ◽  
Transport Volume ◽  
Source Sink

Nitrate (NO-3 ) concentrations in 0·5-mm increments of drainage from adjacent mole- and pipe-drained paddocks of a silt loam soil under pasture near Palmerston North, New Zealand, were measured during 2 winters. The data were simulated using a simple analytical transfer function model (TFM). Urea fertiliser applied at the rate of 120 kg N/ha to one paddock was treated as a pulse input to the pool of resident soil NO-3. A source{sink term was included for plant uptake and net mineralisation (including any effect of denitrification). During the first winter (1990), a TFM using either a 1-parameter Burns probability density function (pdf) for solute travel, or a 2-parameter lognormal pdf, satisfactorily simulated the NO-3 concentration trends and predicted the total amounts of N leached. The pdf parameters were derived from previous chloride leaching data for this site. The best-fit value for the transport volume θst, the key parameter in the Burns pdf, was set at 0·37 m3 /m3 in 1990, as used in previous modelling of sulfate leaching. However, a value of 0 ·25 m3 /m3 in the Burns pdf gave better simulations of the 1991 data. This was probably due to more intense rain events during the early part of the drainage season in 1991 compared with 1990, which resulted in more preferential flow through the soil and a lower value for θst. The simulations for both years showed that ≥50% of the total leachable NO-3 was retained in the soil, despite normal winter drainage of about 300 mm. Ideally, the appropriate value of st should be determined by independent measurement. It may need to be adjusted according to the likely incidence of preferential flow early in the winter when NO-3 concentrations are highest. Provided the average initial soil NO-3 concentration can be estimated and a net source{sink term defined, the amount of NO-3 leached in drained soils can be satisfactorily modelled using the TFM approach with a 1-parameter pdf. Duplex soils which have a fluctuating watertable in the A horizon over an impermeable B horizon may prove to be an analogous system.

Leaching of copper from contaminated soil following the application of EDTA. I. Repacked soil experiments and a model

Soil Research ◽  
2003 ◽  
Vol 41 (2) ◽  
pp. 323 ◽  
Author(s):  
T. Thayalakumaran ◽  
I. Vogeler ◽  
D. R. Scotter ◽  
H. J. Percival ◽  
B. H. Robinson ◽  
...  
Keyword(s):  
Contaminated Soil ◽  
Coming Out ◽  
Sandy Loam ◽  
Soil Columns ◽  
Volcanic Origin ◽  
Sink Term ◽  
Loam Soil ◽  
Copper Contaminated ◽  
Source Sink ◽  
Similar Soil

The EDTA-enhanced remediation of copper contaminated sandy-loam soil of volcanic origin was investigated. The soil, from an orchard, was contaminated with about 250 mg/kg of copper due to the extensive use of copper sprays. Copper-contaminated soil was packed into 100-mm-long columns, and solutions of Na2H2EDTA with CaCl2, raised to a pH of 6.2, were applied at a flow rate of 24 mm/h. Application of an excess of 0.01 M EDTA leached about half the acid-extractable copper from the soil; most of it coming out in the first 3 liquid-filled pore volumes (PV). Also a 0.5 PV pulse of 0.001 M EDTA was applied to similar soil columns and then either leached immediately with 0.005 M CaCl2, or left for periods of up to 1 month before leaching. With immediate leaching, 70% of the EDTA applied was complexed with copper in the leachate, but after a month's delay only 24% was complexed with copper in the leachate, the rest being complexed with iron. There was no evidence of EDTA retardation or adsorption. The experimental results were simulated using the convection–dispersion equation, incorporating a source/sink term. This described the competing time-dependent reactions of copper and iron with EDTA, and the reversion of CuEDTA2– to adsorbed Cu2+ and Fe(III)EDTA– in solution. Reasonable simulations were achieved, mostly within errors of observation.

scholarly journals High-order scheme for the source-sink term in a one-dimensional water temperature model

PLoS ONE ◽  
2017 ◽  
Vol 12 (3) ◽  
pp. e0173236
Author(s):  
Zheng Jing ◽  
Ling Kang
Keyword(s):  
Water Temperature ◽  
High Order ◽  
Temperature Model ◽  
One Dimensional ◽  
High Order Scheme ◽  
Sink Term ◽  
Order Scheme ◽  
Source Sink

scholarly journals Investigating the Effect of Three Nitrate Fertilizers on Nitrate Leaching under the Root Zone in Clay Loam Soil

2009 ◽  
Vol 5 (3) ◽  
pp. 387-392
Author(s):  
Thamer Ahmed Mohammed ◽  
M. Nooshin ◽  
Megat Johari Megat M Noor ◽  
A. Liaghat
Keyword(s):  
Nitrate Leaching ◽  
Root Zone ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Loam Soil

scholarly journals Export of <sup>134</sup>Cs and <sup>137</sup>Cs in the Fukushima river systems at heavy rains by Typhoon Roke in September 2011

2013 ◽  
Vol 10 (2) ◽  
pp. 2767-2790 ◽  
Author(s):  
S. Nagao ◽  
M. Kanamori ◽  
S. Ochiai ◽  
S. Tomihara ◽  
K. Fukushi ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Heavy Rain ◽  
Rain Event ◽  
Normal Flow ◽  
Flow Conditions ◽  
Pulse Input ◽  
Heavy Rain Event ◽  
Coastal Marine ◽  
Rain Events ◽  
Heavy Rains

Abstract. Effects of a heavy rain event on radiocesium export were studied at stations on the Natsui River and the Same River in Fukushima Prefecture, Japan after Typhoon Roke during 21–22 September 2011, six months after the Fukushima Daiichi Nuclear Power Plant accident. Radioactivity of 134Cs and 137Cs in river waters was 0.011–0.098 Bq L−1 at normal flow conditions during July–September in 2011, but it increased to 0.85 Bq L−1 in high flow conditions by heavy rains occurring with the typhoon. The particulate fractions of 134Cs and 137Cs were 21–56% in the normal flow condition, but were close to 100% after the typhoon. These results indicate that the pulse input of radiocesium associated with suspended particles from land to coastal ocean occurred by the heavy rain event. Export flux of 134Cs and 137Cs by the heavy rain accounts for 30–50% of annual radiocesium flux in 2011. Results show that rain events are one factor controlling the transport and dispersion of radiocesium in river watersheds and coastal marine environments.

Nitrate Leaching in a Tile-Drained Silt Loam Soil

2000 ◽  
Vol 64 (2) ◽  
pp. 517-527 ◽  
Author(s):  
J. A. de Vos ◽  
D. Hesterberg ◽  
P. A. C. Raats
Keyword(s):  
Nitrate Leaching ◽  
Silt Loam ◽  
Silt Loam Soil ◽  
Loam Soil

Specific contributions of decaying alfalfa roots to nitrate leaching in a Kalamazoo loam soil

2005 ◽  
Vol 109 (1-2) ◽  
pp. 97-106 ◽  
Author(s):  
Yasemin Kavdır ◽  
Daniel P. Rasse ◽  
Alvin J.M. Smucker
Keyword(s):  
Nitrate Leaching ◽  
Loam Soil

Transport of iodide in structured soil under spring barley during irrigation experiment analyzed using dual-continuum model

Biologia ◽  
2013 ◽  
Vol 68 (6) ◽  
Author(s):  
Jaromír Dušek ◽  
Ľubomír Lichner ◽  
Tomáš Vogel ◽  
Vlasta Štekauerová
Keyword(s):  
Continuum Model ◽  
Preferential Flow ◽  
Root Zone ◽  
Spring Barley ◽  
Soil Matrix ◽  
Iodide Transport ◽  
Loam Soil ◽  
Water Drops ◽  
Structured Soil ◽  
The One

AbstractTransport of radioactive iodide 131I− in a black clay loam soil under spring barley in an early ontogenesis phase was monitored during controlled field irrigation experiment. It was found that iodide bound in the soil matrix could be mobilized by the surface leaching enhanced by mechanical impact of water drops and transported below the root zone of crops via soil cracks. The iodide transport through structured soil profile was simulated by the one-dimensional dual-continuum model, which assumes the existence of two inter-connected flow domains: the soil matrix domain and the preferential flow domain. The model predicted relatively deep percolation of iodide within a short time, in a good agreement with the observed vertical iodide distribution in soil. The dual-continuum approach proved to be an adequate tool for evaluation of field irrigation experiments conducted in structured soils.

Modelling DCD effect on nitrate leaching under controlled conditions

Soil Research ◽  
2007 ◽  
Vol 45 (4) ◽  
pp. 310 ◽  
Author(s):  
Iris Vogeler ◽  
Adeline Blard ◽  
Nanthi Bolan
Keyword(s):  
Nitrate Leaching ◽  
Nitrification Inhibitor ◽  
Life Time ◽  
Potential Effect ◽  
Nitrification Rate ◽  
Nitrogen Transformations ◽  
Column Leaching ◽  
Loam Soil ◽  
Leaching Experiments ◽  
The Difference

Effects of nitrogen losses through nitrate leaching are one of the major environmental issues worldwide. To determine the potential effect of dicyandiamide (DCD), a nitrification inhibitor, on the transformation of urea nitrogen and subsequent nitrate leaching, incubation and column leaching experiments were performed. Tokomaru silt loam soil was treated with urea, DCD, or urea plus DCD. A control was also used. In the laboratory incubation experiment, the conversion of urea to ammonium (i.e. ammonification process or urea hydrolysis) occurred within a day, thereby increasing the soil pH from 5.8 to 6.9. DCD did not affect the ammonification process. However, DCD did slow down the subsequent oxidation of ammonium to nitrate (i.e. nitrification process). The half-life time of ammonium in this soil was increased from 9 days for the urea treatment to 31 days for the urea + DCD treatment. The production of nitrate was 5 times slower when DCD was added. In the leaching experiments, half the columns were leached after 1 day of incubation (Day 1), the other half 7 days later (Day 7). For Day 1, no significant differences in nitrate leaching could be seen between the treatments, as the nitrification had not yet taken place. For Day 7, DCD decreased nitrate leaching by 71% with a corresponding decrease in nitrate-induced cation leaching, including ammonium. Thus, DCD seems to be effective in decreasing both ammonium and nitrate leaching, but its high solubility and thus mobility could be a limitation to its use. The convection–dispersion equation, including source–sink terms for nitrogen transformations, ammonification, and nitrification rate constants, and a factor for nitrification inhibition by DCD, accounting for degradation and efficiency of DCD, could be used reasonably well to simulate nitrate leaching from the column leaching experiments. However, model parameter values for nitrification rate, and efficiency and decay rate for DCD, were different from those obtained from the incubation experiments, which was probably because of the difference in water content of soil between the incubation and leaching experiments.

The effect of preferential flow of dairy cow urine and simulated rainfall on movement of potassium through undisturbed topsoil cores

Soil Research ◽  
1990 ◽  
Vol 28 (6) ◽  
pp. 857 ◽  
Author(s):  
PH Williams ◽  
MJ Hedley ◽  
PEH Gregg
Keyword(s):  
Dairy Cow ◽  
Preferential Flow ◽  
Structural Characteristics ◽  
Near Field ◽  
Tritiated Water ◽  
Soil Surface ◽  
Field Capacity ◽  
Direct Consequence ◽  
Cow Urine ◽  
Rain Events

Cores of undisturbed topsoil (15 cm in depth and diameter) were taken from a range of soil types to a controlled climate chamber. Urine from dairy cows was spiked with tritiated water (3H2O) and then applied to these cores which had moisture contents near field capacity. Liquid draining from these cores, as a direct consequence of urine application, contained up to 72% of the tritiated water, 74% of the potassium (K), 62% of the nitrogen (N) and 80% of the chloride (Cl) applied in the urine, indicating that urine could flow preferentially beyond the 15 cm depth in these soils. The activity of tritium and the concentrations of K, N and Cl in the effluent indicated that this preferential movement of urine occurred too quickly for sorption reactions to occur between the soil surface and the majority of solutes in the urine. After preferential flow had ceased, the amounts of K leached by subsequent simulated rain events were much smaller than losses immediately following the urine application. Leaching losses were particularly small (accounting for 3-15% of the applied urine K) when the majority of the rain water moved preferentially through the soil cores, thus bypassing the urine K which was in soil micropores or which had been sorbed by the soil. Overall, these results suggest that substantial movement of K (and N) through the topsoil of grazed pastures may occur following a urination event due to preferential flow of dairy cow urine through the soil profile, at least when soils are near field capacity at the time of urine deposition. The extent of this movement through topsoil will be more dependent upon soil structural characteristics rather than soil chemical characteristics.

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