Pollution of Water Resources from Agricultural Fields and Its Control - Practices of Irrigation and On-farm Water Management - page 241

Chapter 7
Pollution of Water Resources from Agricultural
Fields and Its Control
Contents
7.1 Pollution Sources .............................. 242
7.1.1 Point Sources ............................. 242
7.1.2 Nonpoint Sources ........................... 242
7.2 Types of Pollutants/Solutes .......................... 243
7.2.1 Reactive Solute ............................ 243
7.2.2 Nonreactive Solute ........................... 243
7.3 Extent of Agricultural Pollution ........................ 243
7.3.1 Major Pollutant Ions .......................... 243
7.3.2 Some Relevant Terminologies ...................... 244
7.3.3 Factors Affecting Solute Contamination ................. 244
7.3.4 Mode of Pollution by Nitrate and Pesticides ............... 247
7.3.5 Hazard of Nitrate (NO 3 -N) Pollution .................. 248
7.3.6 Impact of Agricultural Pollutants on Surface Water Body and Ecosystem .. 248
7.4 Solute Transport Processes in Soil ....................... 250
7.4.1 Transport of Solute Through Soil .................... 250
7.4.2 Basic Solute Transport Processes .................... 251
7.4.3 Convection-Dispersion Equation .................... 254
7.4.4 Governing Equation for Solute Transport Through Homogeneous Media .. 254
7.4.5 One-Dimensional Solute Transport with Nitrification Chain ........ 256
7.4.6 Water Flow and Solute Transport in Heterogeneous Media ......... 257
7.5 Measurement of Solute Transport Parameters .................. 258
7.5.1 Different Parameters .......................... 258
7.5.2 Breakthrough Curve and Breakthrough Experiment ............ 259
7.6 Estimation of Solute Load (Pollution) from
Agricultural Field .............................. 261
7.6.1 Sampling from Controlled Lysimeter Box ................ 261
7.6.2 Sampling from Crop Field ....................... 261
7.6.3 Determination of Solute Concentration .................. 262
7.7 Control of Solute Leaching from Agricultural
and Other Sources .............................. 265
7.7.1 Irrigation Management ......................... 265