Effect of initial soil water content and application of water on urea applied to pasture

1995 ◽  
Vol 46 (4) ◽  
pp. 821 ◽  
Author(s):  
GN Mundy
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Simulated Rainfall ◽  
Moist Soil ◽  
Mineral N ◽  
Initial Soil ◽  
Dry Soil

A 15N study with microplots was conducted to determine the effect of initial soil water content and of water application on the recovery of 15N-labelled urea applied at 60 kg N/ha to a paspalum-dominant pasture. A second experiment with the same pasture type investigated the effects of individual urea granules on soil pH and mineral nitrogen (N) after application to a moist soil with and without follow up rain and to wet soil without follow up rain. The 15N balance showed that initial soil water content and 10 mm of simulated rainfall affected the recovery of 15N in the soil/pasture. Fertilizer recovery was lowest (79%) from dry soil (evaporation minus rainfall (ER) 50 mm) without rainfall, but when the initial soil water (ER 25 mm) was higher, the recovery of fertilizer was greater. Simulated rainfall (10 mm) after urea application to the dry soil increased urea recovery to 90%. The recovery of applied 15 N was greater than 90% following the application of the urea to saturated soil (E-R 0 mm) and was comparable to the recommended procedure of irrigation after application. In experiment 2, the initial soil water content and follow up rain (10 mm) were important factors affecting soil pH and mineral N concentrations at urea granule sites after urea was applied to soil. Urea increased soil pH of granule sites to more than 8.5 in moist soil, but with 10 mm of rain or with wet soil, pH only reached 7.6. Similar effects with soil mineral N were also measured. The effects of these changes in pH and mineral N are discussed in relation to recovery of urea applied to pasture soil.

Factors influencing salt and water movement near crystalline salts in relatively dry soil

Soil Research ◽  
1974 ◽  
Vol 12 (2) ◽  
pp. 77 ◽  
Author(s):  
DR Scotter
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Water Movement ◽  
Factors Influencing ◽  
Initial Soil ◽  
Crystalline Salt ◽  
Water Accumulation ◽  
Dry Soil

Crystalline salts were placed at one end of sealed tubes of initially uniformly wet soil. The effect of soil texture, the initial soil water content, temperature, and the particular salt used on the resulting water and salt distributions in the soil was studied. In all experiments using relatively dry soil a zone of water accumulation adjacent to the salt, and a zone of water depletion further away from the salt, developed. Dissolved salt moved into the wetter zone next to the salt. The rate at which salt dissolved and moved out into the soil was found to depend very strongly on the solubility and saturated solution vapour pressure of the salt used, and the initial soil water content. Soil temperature and texture were less important factors. In some experiments quite large amounts of water accumulated in the crystalline salt, apparently when adequate contact was not maintained between the salt and the soil as the salt dissolved.

scholarly journals Process-based modelling of NH<sub>3</sub> exchange with grazed grasslands

2017 ◽  
Vol 14 (18) ◽  
pp. 4161-4193 ◽  
Author(s):  
Andrea Móring ◽  
Massimo Vieno ◽  
Ruth M. Doherty ◽  
Celia Milford ◽  
Eiko Nemitz ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Regional Scale ◽  
Scale Model ◽  
Nh3 Emission ◽  
Initial Soil ◽  
The Difference

Abstract. In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches, was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch-scale model. The reason for these different sensitivities is dual. Firstly, the difference originates from the different scales. Secondly, the difference can be explained by the different initial soil pH and physical properties, which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way showed a good agreement with those from the simulations with the original approach, accounting for a dynamically changing soil pH. These results suggest a way for model simplification when GAG_field is applied later at regional scale.

scholarly journals Process-based modelling of NH<sub>3</sub> exchange with grazed grasslands

2017 ◽  
Author(s):  
Andrea Móring ◽  
Massimo Vieno ◽  
Ruth M. Doherty ◽  
Celia Milford ◽  
Eiko Nemitz ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Regional Scale ◽  
Scale Model ◽  
Emission Model ◽  
Nh3 Emission ◽  
Initial Soil

Abstract. In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch scale model. This can be explained by the different initial soil pH and physical characteristics which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way showed a good agreement with those from the simulations with the original approach, accounting for a dynamically changing soil pH. These results suggest a way for model simplification when GAG_field is applied later for regional scale.

scholarly journals Preferential flow of surface‐applied solutes: Effect of lysimeter design and initial soil water content

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Mark R. Williams ◽  
Oscar Coronel ◽  
Scott J. McAfee ◽  
Laura L. Sanders
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Preferential Flow ◽  
Initial Soil

Distribution of carbon and nutrients and fluxes of mineral nitrogen after clear-felling a Pinusradiata plantation

1990 ◽  
Vol 20 (9) ◽  
pp. 1490-1497 ◽  
Author(s):  
P. J. Smethurst ◽  
E. K. S. Nambiar
Keyword(s):  
Organic Matter ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
N Mineralization ◽  
Soil Depth ◽  
Mineral N ◽  
Southeastern Australia ◽  
Nutrients Fluxes

The effects of clear-felling and slash removal on the distribution of organic matter and nutrients, fluxes of mineral N, and soil water and temperature were studied in a 37-year-old Pinusradiata D. Don plantation, on a sandy Podzol in southeastern Australia. Slash, litter, and the top 30 cm of soil combined contained 1957 kg N•ha−1, of which slash and litter contained 12 and 25%, respectively. Therefore, loss of slash and litter due to burning or other intensive site preparation practices would substantially reduce the N capital at the site. During the first 18 months after clear-felling, soil water content in the clear-felled area was up to 50% higher than in the uncut plantation, but there were only minor differences in soil temperature. Slash removal decreased the water content of litter, but had little effect on the water content or temperature of the soil. In the uncut plantation, N mineralized in litter and soil was completely taken up by the trees. Following clear-felling, rates of N mineralization increased in litter after 4 months, and in soil after 12 months, but changes were less pronounced with slash removal. After clear-felling, increased mineralization and the absence of trees (no uptake) led to increased concentrations of mineral N in both litter and soil, 64–76% of which was leached below the 30 cm soil depth prior to replanting. Despite leaching, concentrations of mineral N after clear-felling remained higher than those in the uncut plantation for at least 3 years.

scholarly journals Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Soils

2018 ◽  
Vol 24 (6) ◽  
pp. 72
Author(s):  
Zena Kamil Rasheed ◽  
Maysoon Basheer Abid
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Transient Flow ◽  
Initial Conditions ◽  
Irrigation System ◽  
Pipe Length ◽  
Ceramic Pipe ◽  
Initial Soil

The problem of water scarcity is becoming common in many parts of the world, to overcome part of this problem proper management of water and an efficient irrigation system are needed.  Irrigation with a buried vertical ceramic pipe is known as a very effective in the management of irrigation water.  The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the HYDRUS/2D software.  Different values of pipe lengths and hydraulic conductivity were selected.  In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions.  Different values of the applied head were assumed in this simulation as boundary conditions.  The results of this research showed that greater spreading occurs in the horizontal direction.  Increasing applied heads, initial soil water contents and pipe hydraulic conductivities, cause increasing the size of wetting patterns but in a few increases.  Also, the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as design equations.        

scholarly journals Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Coarse Soils

2018 ◽  
Vol 13 (4) ◽  
pp. 164-173
Author(s):  
Zena Kamil Rasheed ◽  
Maysoon Basheer Abid
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Transient Flow ◽  
Vertical Direction ◽  
Empirical Formulas ◽  
Pipe Length ◽  
Ceramic Pipe ◽  
Initial Soil

Problem of water scarcity is becoming common in many parts of the world.  Thus to overcome this problem proper management of water and an efficient irrigation systems are needed.  Irrigation with buried vertical ceramic pipe is known as a very effective in management of irrigation water.  The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the software HYDRUS/2D to predict empirical formulas that describe the predicted results accurately.   Different values of pipe lengths and hydraulic conductivity were selected.  In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions.  Different values of applied head were assumed in this simulation as a boundary conditions.  In general, a good agreement was obtained when comparing the predicted results with available measured values.  The results of this research showed that greater spreading occur in vertical direction.  Increasing applied heads, initial soil water contents, pipe hydraulic conductivities, cause increasing the size of wetting patterns.  Also the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as a designing equations.  

Nitrogen and water flows under pasture - wheat and lupin - wheat rotations in deep sands in Western Australia. 2. Drainage and nitrate leaching

1998 ◽  
Vol 49 (3) ◽  
pp. 345 ◽  
Author(s):  
G. C. Anderson ◽  
I. R. P. Fillery ◽  
F. X. Dunin ◽  
P. J. Dolling ◽  
S. Asseng
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Western Australia ◽  
Root Zone ◽  
N Uptake ◽  
Subterranean Clover ◽  
Lower Amount ◽  
Wheat Crop ◽  
Mineral N

Quantification of nitrate (NO-3) leaching is fundamental to understanding the efficiency with which plants use soil-derived nitrogen (N). A deep sand located in the northern wheatbelt of Western Australia was maintained under a lupin (Lupinus angustifolius)-wheat (Triticum aestivum) and a subterranean clover (Trifolium subterraneum) based annual pasture-wheat rotation from 1994to 1996. Fluxes of water and NO-3 through, and beyond, the root-zone were examined. Drainage was calculated on a daily basis from measurements of rainfall, evapotranspiration, and the change in soil water content to a depth of 1·5 m. Evapotranspiration was estimated from Bowen ratio measurements,and soil water content was determined by time domain reflectrometry. Soil was sampled in layers to1·5 m at the onset of winter rains and analysed for NO-3 . Ceramic suction cups were installed at 0·25, 0·4, 0·6, 0·8, 1·0, 1·2, and 1·4 m to sample soil solution from June to mid August. The NO-3 leached from each layer was computed by multiplying the daily drainage through each layer by the estimated concentration of NO-3 within the layer. The estimated concentration of NO-3 in a layer was calculated by taking into account NO-3 either entering that layer through mineralisation and leachingor leaving the layer through plant uptake. Mineral N was added to the surface 0·2 m in accordance with measured rates of net N mineralisation, and daily N uptake was calculated from the measured above-ground plant N derived from soil N. Root sampling was undertaken to determine root lengthdensity under pastures, lupin, and wheat. Cumulative drainage below 1·5 m was similar under wheat and lupin, and accounted for 214 mmfrom 11 May to 15 August 1995 and 114 mm from 2 July to 15 September 1996. The cumulative evapotranspiration (Ea) over these periods was 169 mm from a wheat crop in 1995, and 178 mm from a lupin crop in 1996. The amount of NO-3 in soil at the start of the growing season was afiected by previous crop, with a lower range following wheat (31-68 kg N/ha) than following legumes (40-106 kgN/ha). These large quantities of NO-3 in the soil at the break of the season contributed substantially to NO-3 leaching. Leaching of NO-3 below 1·5 m in wheat crops accounted for 40-59 kg N/ha where these followed either lupin or pasture. In contrast, less NO-3 was found to leach below 1·5 m in pastures (17-28 kg N/ha). Greater N uptake by capeweed (Arctotheca calendula L.) than by either wheat or lupin was the main reason for the lower amount of NO-3 leached in pastures.

Effect of Initial Soil Water Content on Output Parameters of Sirmod Software Under Types of Different Irrigation Management

2019 ◽  
Vol 68 (4) ◽  
pp. 740-752
Author(s):  
Ali Javadi ◽  
Behrouz Mostafazadeh‐Fard ◽  
Mohammad Shayannejad ◽  
Hamed Ebrahimian
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Irrigation Management ◽  
Initial Soil
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