caa a22 4500 477111726 CHVBK 20180405111611.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00015314 doi (NATIONALLICENCE)springer-10.1007/BF00015314 Determination of K forms in K-fertilized soils by electro-ultrafiltration [Elektronische Daten] [B. Rubio, F. Gil-Sotres] We confirmed the suitability of electro-ultrafiltration (EUF) for (a) determination of the distribution of potassium fertilizer among the various forms of potassium in soils with a predominance of micaceous minerals in their clay fraction, and (b) investigated the effects of the degree of openness of the dominant micaceous mineral and of incubation time on the kinetics of the EUF extraction of K from these soils. Samples of illitic, mixed-layer and vermiculitic soils from Galicia (N.W. Spain) were incubated at field capacity for 450 days with 0 (blank), 5,15 or 25 mg K (as KCl) per 100 g dry soil. After 1, 30, 150 and 450 days, subsamples were removed and repeatedly extracted using electro-ultrafiltration at low (20° C/200 V) and then high (80° C/400 V) temperature/voltage (6 and 10 five-minute extractions, respectively). Five different "pools” of K were identified: solution K (Ks), surface and internal K (collectively, Kp), slowly exchangeable K (Ke) and non-exchangeable K (Ki). The effects of increasing the incubation time depended on the dominant clay mineralogy: after 450 days, the K added to illitic soils was mostly solution K, whereas that added to vermiculitic soils was mostly internal K. For both low and high temperature/voltage EUF experiments, the extraction-time data were best fitted by the Elovich equation (extracted K=a+b ln t). The kinetic coefficient b depended on the incubation time and dominant clay mineral, and for given soil and incubation time increased linearly with the dose of added K. Kluwer Academic Publishers, 1996 EUF-K nationallicence Galician soils nationallicence K desorption nationallicence K fixation nationallicence K forms nationallicence K kinetics nationallicence EUF : Electroultrafiltration nationallicence Ks : Solution potassium nationallicence Kp : Easily exchangeable (surface + internal) potassium nationallicence Ke : Slowly exchangeable potassium nationallicence Ki : Non-exchangeable potassium nationallicence Rubio B. Departamento de Recursos Naturales y Medio Ambiente, Facultad de Ciencias, Universidad de Vigo, Apdo 874, 36200, Vigo, Spain aut Gil-Sotres F. Departamento de Recursos Naturales y Medio Ambiente, Facultad de Ciencias, Universidad de Vigo, Apdo 874, 36200, Vigo, Spain aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 180/2(1996-03-01), 303-310 0032-079X 180:2<303 1996 180 11104 https://doi.org/10.1007/BF00015314 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00015314 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rubio B. Departamento de Recursos Naturales y Medio Ambiente, Facultad de Ciencias, Universidad de Vigo, Apdo 874, 36200, Vigo, Spain aut NATIONALLICENCE 700 1- Gil-Sotres F. Departamento de Recursos Naturales y Medio Ambiente, Facultad de Ciencias, Universidad de Vigo, Apdo 874, 36200, Vigo, Spain aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 180/2(1996-03-01), 303-310 0032-079X 180:2<303 1996 180 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer