Document Type : Research Paper

Abstract

The effect on sugar beets of water and nitrogen movement in the soil under different water conditions was assessed over two years (2000-1) at the Khorasan Agricultural Research Center. Three water treatments (no water stress, continuous stress and primary stress) and three N amounts (80, 160 and 240 kg N/ha) were investigated. The amount of moisture depletion in the water treatments was 50%, 80% and 90%, respectively. The leaching estimation and chemistry model (LEACHM) is a process-based model developed by Hutson and Wagenet (1992) that describes water and solute movement, transformation, plant uptake and chemical reactions in unsaturated soils. The model applies numerical techniques to the Richard’s water flow equation and the convection dispersion equation (CDE) using finite difference methods. The LEACHM model contains four modules: LEACH-W simulates only the water regime, LEACH-N simulates nitrogen transport and transformation; LEACH-P simulates the pesticide displacement and degration; LEACH-C simulates the transient movement of inorganic ions. LEACH-N, the version of LEACHM that addresses N dynamics, was selected for this study because it has subroutines to calculate water flow, NO3 leaching, evapotranspiration, heat flow, rate content adjustments for temperature and water content, N transformations and uptake. Mineralization, nitrification, denitrification and volatilization are the major N transformation processes modeled by LEACH-N. The model predicted the amounts of moisture, ammonium and nitrate in the soil with acceptable precision. The correlation between the measured and predicted amounts was significant at the 1% level. Immediately after the application of N, the amounts of ammonium and nitrate in the surface layers increased sharply. The amount of ammonium in the surface layers was less for the non-stress treatment than the other treatments. Ammonium and nitrate uptake decreased at the time of stress, but increased after stress. By increasing the soil depth, the amount of nitrate in the non-stress treatment increased. In stress treatments, the amount of N losses caused by ammonium volatilization, denitrification and nitrate leaching decreased.

Keywords

Acutis, M. 1997. Modeling leaching of nitrate: Calibration and validation of LEACHN model in different soils and forage crops .Rivista-di-Agronomia. (Italy). 31(1): 42-51.
Alan, D. J., Miguel, L. C. Daniel, V. M. and David, E. R. 1999. LEACHN simulations of nitrogen dynamics and water drainage in an ultisol. Agron. J. 91, 597-606.
Alizadeh, A. 1999. Relation of Water, Soil and Plant. Emam Reza University Pub. Mashhad. Iran. (in Farsi)  
Antonopoulos, V. Z. 1997. Simulation of soil moisture dynamics on irrigated cotton in semi-arid climates. Agric. Water Manag. 34, 233-246.
Antonopoulos, V. Z. 2000. Modeling of soil water dynamics in an irrigated corn field using direct pedotransfer functions for hydraulic properties. Irrig. Drain. Sys. 14, 325-342.
Focht, D. D. and Verstraete, W. 1977. Biochemical ecology of nitrification and denitrification. Adv. Microb. Ecol. 1, 135-214.
Groves, S. J. and Baily, R. J. 1997. The influence of sub-optimal irrigation and drought on crop yield, N uptake and risk of N leaching from sugar beet. Soil Use Manag. 12, 129-133.
Hanks, R. J. and Ritchie, J. T. 1991. Modeling plant and soil systems. Publishers Madison. Wisconsin USA.
Hutson, J. L. and Wagenet, R. J. 1992. LEACHM. Leaching estimation and chemistry model: A process based model of water and solute movement, transformations, plant uptake and chemical reactions in unsaturated zone. Version 3. Dept. of Agronomy. Cornell University. Ithaca. N. Y.
Jabro, J. D., Jemison, J. M. Lengnick, L. L. Fox, R. H. and Fritton, D. D. 1993. Field validation and comparison of LEACHM and NCSWAP models for predicting nitrate leaching. Trans. ASAE 36(6): 1651-1657.
Jabro, J. D., Toth, J. D., Dou,  Z., Fox, R. H. and Fritton, D. D. 1995. Evaluation of nitrogen version of LEACHM for prediction nitrate leaching. Soil Sci. 160(3): 209-217.
Jabro, J. D., Stout, W. L. Fales, S. L. and Fox, R. H. 1997. Nitrate leaching from soil core lysimeters treated with urine or feces under orchard grass: Measurement and simulation. J. Environ. Qual. 26, 89-94.
Jemison, J. M., Jabro, J. D. and Fox, R. H. 1994. Evaluation of LEACHM: II. Simulation of nitrate leaching from nitrogen-fertilized and manure corn. Agron. J. 86, 852-859.
Jolaini, M., Pazira, A. Parehkar, M. and Abedi, M. J. 2005. Estimation the moisture in sugar beet root development limit by using LEACHM model. J. Agric. Sci. Natural Resources of Gorgan University. Iran. Special Issue on Agronomy and Plant Breeding Dec.-Jan.12, 28-38. (In Farsi) 
Ling, Ge. and El-Kadi, A. I. 1998. A Lumped parameter model for nitrogen transformation in the unsaturated zone. Water Resour. Res. 34(2): 203-212.
Loague, K. and Green, R. E. 1991. Statistical and graphical methods for evaluating solute transport models: Overview and application. J. Contam. Hydrol. 7, 51-73.
Mirnia, S., Mohammadian, M. and Fallah, W. M. 2000. Nitrogen management in irrigated agriculture. Mazandaran University Pub. Iran. (in Farsi)    
Ng, H. Y. F., Drury, C. F. Serem, V. K. Tan, C. S. and Gaynor, J. D. 2000. Modeling and testing of the effect of tillage, cropping and water management practices on nitrate leaching in clay loam soil. Agri. Water Manag. 43, 111-131.
Nima, M. N., and Hanks, R. J. 1973. Model for estimation of soil water, plant, and atmospheric interrelations: I. Description and sensitivity. Soil Sci. Am. Proc. 37, 522-527.
Parehkar, M. 1998. Recharge processes under arid semi-arid areas (laboratory experiment and modeling). Ph.D. Thesis. Cranfield University. Silsoe. England.
Ramos, C. and Carbonell, E. A. 1991. Nitrate leaching and soil moisture prediction with the LEACHM model. Fertilizer Res. 27, 171-180.
Sogbedji, J. M., Van Es, H. M. and Hutson, J. L. 2001a. N fate and transport under variable cropping history and fertilizer rate on loamy sand and clay loam soils: I. Calibration of the LEACHN model. Plant and Soil. 229, 57-70.
Sogbedji, J. M., Van Es, H. M. Hutson, J. L. and Geohing, L. D. 2001b. N fate and transport under variable cropping history and fertilizer rate on loamy sand and clay loam soils: II. Performance of LEACHMN model using different calibration scenarios. Plant and Soil. 229, 71-82.
Sogbedji, J. M., Van Es, H. M. Klausner,  S. D. Bouldin,  D. R. and Cox, W. J. 2001c. Spatial and temporal processes affecting nitrogen availability at the landscape scale. Soil Till. Res. 58,233-244.
Soudi, B., Agbani, M. and Badraoui, M. 1997. Impact of N-fertigation of sugar beet on nitrate leaching. Comptes Rendusdes Congresde Institut InternationaldeRecherchesBetteravieres, Belgium. 60, 265-271.
Vickner, S. S., Hoag, D. L. Frasier,  W. M. and Ascoagh, J. C. 1998. A dynamic economic analysis of nitrate leaching corn production under nonuniform irrigation conditions. Am. Agric. Econ (USA). 80(2): 397-408.
Winter, S. R. 1990. Sugarbeet response to nitrogen as affected by seasonal irrigation. Agron. J. 82, 984-988.