Land Degradation and Pedological Processes in a Changing Climate

320R. Lal / Pedologist (2012) 315-325ter erosion, wind erosion, tillage erosion, desertification,salinization, and physical degradation. Other methodsused have been described by Oldeman and Van Lynden(1998), Dregne (1998), and Bai et al. (2008). Because ofthe diverse methods used, results are often not comparable.Thus, there is a strong need to standardize the methodology,and relate it to its impact on the loss of NPP andagronomic productivity.Table 1. Methods of assessment of land degradationIIIIIIIVVVIVIIVIIILand Degradation Process Method ReferenceWater Erosion• Stream bank Mass movement Channel side slope evolution Lohnes (1991)• Cropland erosion Rill/inter-rill Assessment of liquid and Wicherek (1991)solid flow rates• Cropland erosion Rill/inter-rill Erosion rate Jankauskas et al. (2002)• Landscape erosion Decline in rooting depth P movement downslope Kirkby et al. (1997)• Stream flow Riparian zone Paired catchment Scott (1999)• Sediment yieldPedological, hydrogeomorphologicalprocessesRunoff measurement Cammeraat and Kooijman(2009)• Soil erosion severity Landscape processes Genetic soil horizon Jankauskas and Fullen (2002)• Hillslope erosion Rill, inter-rill Modeling Rneard et al. (1991; 1994;1997), Nearing et al. (1994)Wind Erosion• Soil movement Wind erosivity Modeling Skidmore (1994)• Wind:water driven sediment Aeolian and fluvial sediment Climate extreme Field et al. (2011)transportTillage Erosion• Soil movementSoil redistribution, diffusiveprocess137Cs analysis Govers et al. (1996)Desertification• Sand drift Vegetation/soil degradation NDVI from the Red and IR Dhir and Sharma (1991)Bands Soil Brightness index• Soil surface properties Soil surface roughness and Remote sensing Anderson and Croft (2009)moisture• Steppe degradationUnwanted morphological Pedological assessment Meyer et al. (2008)processes• Land cover Ecosystem transformation Modeling (descriptive,empirical, statistical,dynamic)Lambin (1997)Salinization• Human-induced Salinity in the root zone Surface & ground water Ghassemi et al. (1991)models• Productivity Crop tolerance Species adaptation models Rozema and Flowers (2008)• Global land area Processes of salinization Carbon stock Lal (2009)• Secondary salinization Soil structural stability Spatial analysis Odeh and Onus (2008)• Salt affected soils Salt balance Spatial scales Thayalakumaran et al. (2007)Physical Degradation• Decline in soil structure Slaking Permeability Coughlan et al. (1991)• Soil compaction Changes in bulk density Porosity & pore size Horn et al. (1995)distribution• Aggregation Macro- and microaggregates Aggregate stability Boix-Fayos et al. (2001)Vegetation Degradation• Overgrazing Denudation Satellite, Remote sensing Hill et al. (1998)Economic Loss• Cost of land degradation Productivity decline Measure of economic losses Bojö (1996)