0187-5779 0187-5779 S0187-57792013000300105 Spain Mexico 00 06 2013 00 06 2013 31 2 105 114

2011 109 8-17 2008 72 1774-81 1997 668 140- 162 1992 2005 34 139-48 1965 891-900 2007 36 1137-44 2006 366 1-11 IUSS (International Union of Soil Sciences) 2007 2012 123 69-76 2009 163 563-7 2011 54 642-50 2005 28 125-37 2006 38 327-41 2004 504 217-26 1990 275-98 2004 79 7-31 1978 USDA (United States Department of Agriculture) 1999 1987 19 703-7 1965 29 677- 678 2002 47 1103-11 2009 154 69-75 2011 223 519-32 2013 90 2606-13