Evaluation of soils for use as liner materials: a soil chemistry approach.
Movement of NH(4)(+) below animal waste lagoons is generally a function of the whole-lagoon seepage rate, soil mineralogy, cations in the lagoon liquor, and selectivity for NH(4)(+) on the soil-exchange sites. Binary exchange reactions (Ca(2+)-K(+), Ca(2+)-NH(4)(+), and K(+)-NH(4)(+)) were conducted on two soils from the Great Plains and with combinations of these soils with bentonite or zeolite added. Binary exchanges were used to predict ternary exchanges Ca(2+)-K(+)-NH(4)(+) following the Rothmund-Kornfeld approach and Gaines-Thomas convention. Potassium and NH(4)(+) were preferred over Ca(2+), and K(+) was preferred over NH(4)(+) in all soils and soils with amendments. Generally, the addition of bentonite did not change cation selectivity over the native soils, whereas the addition of zeolite did. The Rothmund-Kornfeld approach worked well for predicting equivalent fractions of cations on the exchanger phase when only ternary-solution phase compositions were known. Actual swine- and cattle-lagoon solution compositions and the Rothmund-Kornfeld approach were used to project that native soils are predicted to retain 53 and 23%, respectively, of the downward-moving NH(4)(+) on their exchange sites. Additions of bentonite or zeolite to soils under swine lagoons may only slightly improve the equivalent fraction of NH(4)(+) on the exchange sites. Although additions of bentonite or zeolite may not help increase the NH(4)(+) selectivity of a liner material, increases in the overall cation exchange capacity (CEC) of a soil will ultimately decrease the amount of soil needed to adsorb downward-moving NH(4)(+).
DeSutter
Tom M
TM
Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.
Pierzynski
Gary M
GM
D000641:Ammonia / Q000032:analysis / Q000737:chemistry*; D000818:Animals; D000829:Animals, Domestic; D001546:Bentonite / Q000737:chemistry; D008372:Manure; D008962:Models, Theoretical; D012987:Soil; D014865:Waste Disposal, Fluid / Q000379:methods*; D017641:Zeolites / Q000737:chemistry
D008372:Manure; D012987:Soil; D001546:Bentonite; D017641:Zeolites; D000641:Ammonia