Encyclopedia of soils in the environment/ 3.

N NEMATODES D A Neher and T O Powers 1 NEUTRON SCATTERING M J Fayer and G W Gee 6 NITROGEN IN SOILS Cycle M S Coyne and W W Frye 13 Nitrates D S Powlson and T M Addiscott 21 Nitrification J I Prosser 31 Plant Uptake A Hodge 39 Symbiotic Fixation J I Sprent 46 NITROGEN FERTILIZERS see FERTILIZERS AND FERTILIZATION NUCLEAR WASTE DISPOSAL G W Gee, P D Meyer and A L Ward 56 NUTRIENT AVAILABILITY N K Fageria and V C Baligar 63 NUTRIENT MANAGEMENT G D Binford 71 VOLUME 3 O ORGANIC FARMING C A Francis 77 ORGANIC MATTER Principles and Processes M Schnitzer 85 Genesis and Formation K M Haider and G Guggenberger 93 Interactions with Metals N Senesi and E Loffredo 101 ORGANIC RESIDUES, DECOMPOSITION A J Franzluebbers 112 ORGANIC SOILS D L Mokma 118 OVERLAND FLOW T S Steenhuis, L Agnew, P Ge´rard-Marchant and M T Walter 130 OXIDATION–REDUCTION OF CONTAMINANTS C J Matocha 133 P PADDY SOILS C Witt and S M Haefele 141 PARENT MATERIAL see PEDOLOGY: Basic Principles; FACTORS OF SOIL FORMATION: Parent Material PEDOLOGY Basic Principles M J Singer 151 Dynamic F C Ugolini 156 PEDOMETRICS I O A Odeh and A B McBratney 166 PENMAN, HOWARD LATIMER J L Monteith 176 PENMAN–MONTEITH EQUATION R Allen 180 PERCOLATION see HYDRODYNAMICS IN SOILS PERMAFROST see POLAR SOILS PERMEABILITY see HYDRODYNAMICS IN SOILS PERSISTENT ORGANIC POLLUTANTS (POPS) see POLLUTANTS: Persistent Organic (POPs) PESTICIDES R H Bromilow 188 PETROLEUM see HYDROCARBONS pH N Bolan and K Kandaswamy 196 PHOSPHORUS IN SOILS Overview J T Sims and P A Vadas 202 Biological Interactions M D Mullen 210 PHYTOTOXIC SUBSTANCES IN SOILS M Qadir, S Schubert and D Steffens 216 PLANT–SOIL–WATER RELATIONS R A Feddes and J C van Dam 222 PLANT–WATER RELATIONS C Gimenez, M Gallardo and R B Thompson 231 POISEUILLE’S LAW see HYDRODYNAMICS IN SOILS POLAR SOILS J C F Tedrow 239 POLLUTANTS Biodegradation P B Hatzinger and J W Kelsey 250 Effects on Microorganisms M E Fuller 258 Persistent Organic (POPs) D Johnson 264 POLLUTION Groundwater H Rubin 271 Industrial S P McGrath 282 POLYMERS AND MICROORGANISMS M C Rillig 287 POORLY CRYSTALLINE ALLUMINOSILICATES see AMORPHOUS MATERIALS POROSITY AND PORE-SIZE DISTRIBUTION J R Nimmo 295 POTASSIUM IN SOILS P M Huang, J M Zhou, J C Xie and M K Wang 303 PRECIPITATION, WATERSHED ANALYSIS J V Bonta 314 PRECIPITATION–DISSOLUTION PROCESSES W P Robarge 322 PRECISION AGRICULTURE see SITE-SPECIFIC SOIL MANAGEMENT PREFERENTIAL FLOW see UNSTABLE FLOW; MACROPORES AND MACROPORE FLOW, KINEMATIC WAVE APPROACH PRODUCTIVITY D L Karlen 330 PROFILE see MORPHOLOGY PROTOZOA W Foissner 336 Q QUALITY OF SOIL B J Wienhold, G E Varvel and J W Doran 349 R RADIATION BALANCE J L Hatfield, T J Sauer and J H Prueger 355 RADIONUCLIDES see ISOTOPES IN SOIL AND PLANT INVESTIGATIONS RAINFED FARMING see DRYLAND FARMING RANGE MANAGEMENT G L Anderson 360 RECYCLING OF ORGANIC WASTES see POLLUTANTS: Biodegradation REDISTRIBUTION see WATER CYCLE REDOX POTENTIAL R D DeLaune and K R Reddy 366 REDOX REACTIONS, KINETICS P S Nico and S Fendorf 372 REMEDIATION OF POLLUTED SOILS E Lombi and R E Hamon 379 REMOTE SENSING Organic Matter D K Morris, C J Johannsen, S M Brouder and G C Steinhardt 385 Soil Moisture T J Jackson 392 RHIZOSPHERE A C Kennedy and L Z de Luna 399 RICHARDS, LORENZO A. W R Gardner 407 ROOT ARCHITECTURE AND GROWTH L E Jackson 411 ROOT EXUDATES AND MICROORGANISMS B-J Koo, D C Adriano, N S Bolan and C D Barton 421 S SALINATION PROCESSES I Shainberg and G J Levy 429 SALINITY Management D Hillel 435 Physical Effects D Russo 442 SALT BALANCE OF SOILS see SALINATION PROCESSES SALT-AFFECTED SOILS, RECLAMATION R Keren 454 SAND DUNES H Tsoar 462 SATURATED AND UNSATURATED FLOW see HYDRODYNAMICS IN SOILS; VADOSE ZONE: Hydrologic Processes SCALING Physical Properties and Processes G Sposito 472 Transport Processes R P Ewing 477 SEPTIC SYSTEMS R L Lavigne 485 SHIFTING CULTIVATION R Lal 488 SITE-SPECIFIC SOIL MANAGEMENT C J Johannsen and P G Carter 497 SLASH AND BURN AGRICULTURE see SHIFTING CULTIVATION SLUDGE see WASTE DISPOSAL ON LAND: Liquid; Municipal SODIC SOILS G J Levy and I Shainberg 504 SOIL–PLANT–ATMOSPHERE CONTINUUM J M Norman and M C Anderson 513 SOLUTE TRANSPORT M C Sukop and E Perfect 521 SORPTION Metals D L Sparks 532 Organic Chemicals B Xing and J J Pignatello 537 Oxyanions C P Schulthess, H Wijnja and W Yang 548 SORPTION–DESORPTION, KINETICS D L Sparks 556 SPATIAL PATTERNS J H Go¨rres and J A Amador 562