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Charge Characteristics and Nitrate Retention By Two Andepts from South‐Central Chile
Author(s) -
Espinoza W.,
Gast R. G.,
Adams R. S.
Publication year - 1975
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1975.03615995003900050018x
Subject(s) - potentiometric titration , nitrate , titration , chemistry , electrolyte , surface charge , soil water , titration curve , adsorption , inorganic chemistry , amorphous solid , cation exchange capacity , ion exchange , soil ph , analytical chemistry (journal) , ion , environmental chemistry , geology , soil science , electrode , organic chemistry
Charge characteristics of two Andepts, or volcanic‐ash‐derived soils, from south‐central Chile were studied using a combination of nitrate retention, pH dependent cation exchange capacity and pH titration curves. Nitrate retention was determined by washing the soil with KNO 3 solutions having the appropriate concentration and pH and determining the amount of nitrate adsorbed. Net surface charge was determined from potentiometric titration curves conducted using a batch technique. Results show that both soils have a complex mixture of pH dependent and permanent charge surfaces. The maximum pH dependent charge is in the range of 15 to 20 meq/100g at either very low or very high pH and high electrolyte concentration. The permanent negative charge is in the range of 45 meq/100g and is apparently the result of ion substitutions and lattice vacancies in X‐ray amorphous oxides and hydrous oxides rather than 2:1 type clay minerals.