Modeling Urea, Ammonium, and Nitrate Transport and Transformations in Flooded Soil Columns

Li, Ma; Lindau, C. W.; Hongprayoon, C.; Burhan, W.; Jang, Byeong-Chun; Patrick, W. H.; Selim, H. M.

doi:10.1097/00010694-199902000-00007

Cited by 16 publications

(11 citation statements)

References 20 publications

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“…A default residual soil water content of 0.027 cm 3 /cm 3 was assumed for all the layers based on Rawls et al (1982). Lateral K sat (LK sat ) and hydraulic gradient (HG) for lateral flow were fitted based on measured soil water content, tile flow, and water table measurement using an optimization scheme (Table 2) (Ma et al, 1999). Detailed model calibration and results are shown in Saseendran et al (2007-this issue).…”

Section: Measured Soil Hydraulic Propertiesmentioning

confidence: 99%

Sensitivity of tile drainage flow and crop yield on measured and calibrated soil hydraulic properties

Ma¹,

Malone²,

Heilman

et al. 2007

Geoderma

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Process-based agricultural system models require detailed description of soil hydraulic properties that are usually not available. The objectives of this study were to evaluate the sensitivity of model simulation results to variability in measured soil hydraulic properties and to compare simulation results using measured and default soil parameters. To do so, we measured soil water retention curves and saturated soil hydraulic conductivity (K sat ) from intact soil cores taken from a long-term experimental field near Nashua, Iowa for the Kenyon-Clyde-Floyd-Readlyn soil association. The soil water retention curves could be well described using the pore size distribution index (λ). Measured λ values from undisturbed soil cores ranged from 0.04 to 0.12 and the measured K sat values ranged from 1.8 to 14.5 cm/h. These hydraulic properties were then used to calibrate the Root Zone Water Quality Model (RZWQM) for simulating soil water content, water table, tile drain flow, and crop yield (corn and soybean) by optimizing the lateral K sat (LK sat ) and hydraulic gradient (HG) for subsurface lateral flow. The measured soil parameters provided better simulations of soil water storage, water table, and N loss in tile flow than using the default soil parameters based on soil texture classes in RZWQM. Sensitivity analyses were conducted for λ, K sat , saturated soil water content (θ s ) or drainable porosity, LK sat , and HG using the Latin Hypercubic Sampling (LHS) and for LK sat and HG also using a single variable analysis. Results of sensitivity analyses showed that RZWQM-simulated yield and biomass were not sensitive to soil hydraulic properties. Simulated tile flow and N losses in tile flow were not sensitive to λ and K sat either, but they were sensitive to LK sat and HG. Further sensitivity analyses using a single variable showed that LK sat in the tile layer was a more sensitive parameter compared to LK sat in other soil layers, and HG was the most sensitive parameter for tile flow under the experimental soil and weather conditions. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. AbstractProcess-based agricultural system models require detailed description of soil hydraulic properties that are usually not available. The objectives of this study were to evaluate the sensitivity of model simulation results to variability in measured soil hydraulic properties and to compare simulation results using measured and default soil parameters. To do so, we measured soil water retention curves and saturated soil hydraulic conductivity (K sat ) from intact soil cores taken from a long-term experimental field near Nashua, Iowa for the Kenyon-Clyde-Floyd-Readlyn soil association. The soil water retention curves could be well described using the pore size distribution index (λ). Measured λ values from undisturbed soil cores ranged from 0.04 to 0.12 and the measured K sat values ranged from 1.8 to ...

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Section: Measured Soil Hydraulic Propertiesmentioning

confidence: 99%

Sensitivity of tile drainage flow and crop yield on measured and calibrated soil hydraulic properties

Ma¹,

Malone²,

Heilman

et al. 2007

Geoderma

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“…Urease is one of the most thoroughly studied soil enzymes because it greatly influences the fate and performance of a widely used fertilizer (urea) (Bremner and Mulvaney, 1978;Ma et al, 1999;Tate, 2002). Urea was reported to be taken up by microorganisms, such as Corynebacterium glutamicum and Paxillus involutus (Jahns and Kaltwasser, 1989;Beckers et al, 2004), or by natural bacterial assemblages (JLrgensen, 2006) and used as their nitrogen source.…”

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confidence: 99%

Tillage Effects on Intracellular and Extracellular Soil Urease Activities Determined by an Improved Chloroform Fumigation Method

Qin

Hu²,

Wang³

et al. 2010

Soil Science

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The intracellular urease activity in soils determined by the chloroform fumigation method is underestimated because of urease degradation by soil protease and denaturation by chloroform. The objectives of this study were to correct this underestimation and to investigate the responses of intracellular, extracellular, and total urease activities to notillage, reduced tillage, and moldboard plowing treatments. Surface layer soils (0Y20 cm) after 8-year different tillage treatments were collected. First, the soil samples were fumigated with ethanol-free chloroform in the presence of a protease inhibitor. Subsequently, a urease addition experiment was conducted to determine what percentage of soil urease was denatured during the fumigation procedure. Our results showed that the corrected intracellular urease activities in soils under no-tillage, reduced tillage, and moldboard plowing accounted for 58.2%, 62.3%, and 51.7% of the total urease activity, respectively. Both no-tillage and reduced tillage significantly increased the intracellular, extracellular, and total urease activities compared with moldboard plowing. The ratio between intracellular and extracellular urease activities was not significantly different between no-tillage and reduced tillage probably because the soil ammonia content was similar under these treatments. The three urease activity pools were significantly correlated with soil organic C, microbial biomass C and N, and available P. These results indicate that both the intracellular and extracellular urease activities were sensitive indicators for monitoring soil quality under different tillage practices.

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“…At this concentration, both silver sulfate and mercuric chloride impaired the colour-forming reaction, and therefore 5 mg/L of phenylmercuric acetate was added to the 2 M potassium chloride solution for the extraction (10 mL solution per g soil). These conditions continued to be used to the present day (Sullivan and Havlin 1991;Greenan et al 1995;Ma et al 1999), but other salt solutions have also been employed (Schulz 1975;Onken and Sunderman 1977). As potassium and chloride ions interfered with the early spectrophotometric methods for the determination of ammonium and nitrate, Onken and Sunderman (1977) prepared a soil extract for the determination of urea, ammonium, nitrate, and nitrite with a solution of sodium sulfate and phenylmercuric acetate (5 mg/L).…”

Section: Extraction Of Urea From Soil Samplesmentioning

confidence: 99%

“…An understanding of these nitrogen transformations in farmlands and wetlands is crucial to establish and maintain optimum fertility and for environmental restoration and care (Bremner 1982;Helyar and Price 1999;Ma et al 1999). A greater awareness of the processes that cause nitrogen loss will increase the efficiency of fertiliser application and therefore improve farm profitability (Weier 1994;Strong and Mason 1999).…”

Section: Introductionmentioning

confidence: 99%

The determination of urea in soil extracts and related samples—a review

2004

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Although the dominant methods for the determination of urea in clinical applications incorporate selective enzymatic hydrolysis of urea, the determination of urea in soil extracts is complicated by the presence of urease inhibitors. The spectrophotometric determination of urea with an acidic solution diacetyl monoxime and semicarbazide is a viable option but traditional manual procedures are time-consuming. New variations on these procedures, based on microplates or flow-injection analysis methodologies, allow a far greater number of samples to be analysed with high precision and sensitivity.

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Modeling Urea, Ammonium, and Nitrate Transport and Transformations in Flooded Soil Columns

Cited by 16 publications

References 20 publications

Sensitivity of tile drainage flow and crop yield on measured and calibrated soil hydraulic properties

Sensitivity of tile drainage flow and crop yield on measured and calibrated soil hydraulic properties

Tillage Effects on Intracellular and Extracellular Soil Urease Activities Determined by an Improved Chloroform Fumigation Method

The determination of urea in soil extracts and related samples—a review

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