The pollution of groundwater by nitrate Is an international probtem due to
excess rates of N fertilization used in modern agriculture. Water application and soil
organic matter content can have a major influence on nitrate teaching. Therefore. with
increasing concern for the influence of N03 leaching into the groundwater. the
objective of the present study were: 1) studying the role of water application rate and
soil organic matter content on leaching at NO) out of soil columns, 2) measuring the
lotal NO) leached from the soil column and 3) evaluating the numerical (HYDRUS-2D)
and analytical(CXTFIT) models to predict the N03 leaching. The present results
indicate that increasing the water application rate increased the N03 leaching. The
N03 leaching ranged between 0.0 to 100% of added nitrate as water application
increased from 0.025 to 0.125 cmfhr. On the other hand. increasing application of
organiC matter to soil decreased the amount of N03 leached from soil columns. The
NO) leaching ranged between 90.96 to 25.47% of added nitrate as organic matter
application increased from 0 to 10% (wfw). The numerical model (HYDRUS-20) and analytical model (CXTF1T) were
successfully predicted NOJ leaching in the present study (R² values of between
observed and estimated ranged from 0.992 to O.999).