ABSTRACT
Nitrogen Dynamics ..................................................................8 1.2.2 Effect of Soil Water on Crop Root Growth ............................10 1.2.3 Nutrient Uptake and Rice-based Cropping System ...............10 1.2.4 Modeling of Water and Solute Transport ...............................11 1.3 Theoretical Considerations ................................................................12 1.3.1 Simulation of Soil Water using HYDRUS-2D .......................13 1.3.1.1 Initial and Boundary Conditions .............................14 1.3.2 Field Water Balance ...............................................................16 1.3.2.1 Ponding Depth .........................................................16 1.3.2.2 Actual Evapotranspiration (AET) ...........................16 1.3.2.3 Surface Runoff ........................................................18 1.3.2.4 Vertical Percolation .................................................18 1.3.2.5 Bare Soil Evaporation During Germination
Period of Rice .........................................................18 1.3.2.6 Bare Soil Evaporation During Turn-In
and Germination Period of Mustard ........................19 1.3.3 OFR Water Balance ................................................................19 1.3.4 Economic Analysis of OFR System .......................................20 1.3.4.1 Present Worth of Cost (PWc) ..................................20 1.3.4.2 Present Worth of Benefit (PWb) .............................21 1.3.4.3 Net Present Value of the OFR System ....................21 1.3.4.4 Benefit-Cost Ratio of the OFR System ..................21 1.3.4.5 Payback Period ........................................................22 1.3.5 Model Evaluation ...................................................................22 1.4 Experimental Study ............................................................................22 1.4.1 Study Area ..............................................................................22 1.4.2 Field Experiments ..................................................................23 1.4.3 Soil .........................................................................................23
