R O C Z N IK I G L E B O Z N A W C Z E T. X X V , D O D A T E K , W A R S Z A W A 1974
A D A M F IR E K
C O M P A R IS O N OF S IM P L E M E T H O D S OF D E T E R M IN IN G TH E S U R F A C E A R E A OF SO ILS
Institute of Soil Science, A gricultural Chemistry, and M icrobiology, A gricu ltu ral U n iversity of Cracow
The solution of many problems in the realm of soil science necessitates a knowledge not only of the total surface area o f soil solidy 'but also of the proportion within the former of the surface areas contained in the inter-lamellar spaces of minerals. Am ong the many methods applied by soil scientists to the determination of the specific surface area of loose materials the following w ere chosen for comparison w ith the glycerol method: (a) estimation of the surface area from water adsorption and desorption, and (b) calculation of the external surface from the mechanical
analysis.
M E TH O D S OF D E T E R M IN IN G OF C O M P U T IN G T H E S U R F A C E A R E A
The external, internal, and total surface areas w ere determined by the glycerol method after the description b y D i a m o n d and K i n t e r [1, 4] and that of S c h w e r t m a n n [9]. The sample mass proposed by the named authors '(0.2 g) was increased to 2.0 g.
Determinations of a monomolecular water layer ( N H ) as w ell as those of maximum hygroscopicity (M H ), i.e., a trimolecular w ater layer, were made b y generally accepted methods [10, 11]. The formulas used to calculate the areas w ere obtained from the all-over equation :
Qc = 1.074 H / 2.76 • 10"8 A (in r r f g " 1) (1)
where :
H — hygroscopicity in g per 100 g of dry soil, 1.074— volume of 1 g of w ater [6],
2.76 • 10“8 cm— diameter of water molecule,
46 A. F irek
Ultimately, the total surface area was calculated from following equations :
flc l = 39 N H m 2g _1 (2)
where :
N H — monomolecular water layer (minimum hygroscopicity in g per 100 g of soil),
Qc2 = 13 M H m2g -1 (3)
where :
M H — »maximum hygroscopicity in g per 100 g of soil.
If the layer of w ater nearest to the soil particles be eliminated, then
ßc3 = 19.5 (M H - N H ) m2g -1 (4)
A computation of the specific area of loose materials with regular particle form is frequently made [5, 9]; the computation is based on particle size and particle form. In the case materials with varying particle size S i г о t к i n and G i n z b u r g [8] proved that a mean particle dia meter m ay be taken as a base for the computation of particle surface area.
Assuming that soil particles show forms intermediate between a sphere and a cube and that their external surfaces are somewhat smaller in area than the surface area o f a cube with an edge equalling the particle dia meter, the surface area of particles of a given fraction m ay be expressed by the equation
Sf = 5 p/yd (5)
where:
p— weight of given fraction, d— mean diameter of particles, f — specific gravity of particles,
Sf— specific surface area of whole fraction.
The external surface area of a soil sample, in all, as the total of areas o f separate fractions, w ill be expressed by the equation.
Qzl = J T [ b pj y dn] in m 2g _1 (6)
where :
p— percentage of given fraction in soil, d— mean fraction diameter,
n— index signifying that the totalling applies to all expressions obtained for separate fractions (1, ..,n) occurring in the soil.
Comparison of sim ple methods.., 47
M A T E R IA L
36 soil samples w ere selected for the investigations. The soils w ere (a) loess-like fine sands found on the mountain foreland of Wieliczka, (b) weathering products of Flysdh sandstones from the environs of Kalwaria, (с) stratified fine sands from the environs of Tenczynek.
A ll the determinations listed in Tab. 1 w ere made w ith the help of generally accepted methods.
T a b l e 1 Mechanical analysis, specific gravity, as well as minimum and maxi mum hygroscopicity
of investigated soils
Sample No.
Mechanical composition in percent of fractions
diameter of fractions in mn Specific gravity g cm” ^ Hygroscopicity g per 100 g soil i.e- о. 1 G.I-О.05 0.05-0.02 0.02-0.005 0.005-0.002 < 0.002 minimum m maximum № 1 11 6 40 26 8 9 2.50 0.34 3.99 2 9 10 37 27 7 10 2.60 0.73 3.00 3 11 7 38 24 8 12 2.62 0.87 n.d. 4 10 7 37 24 5 7 2.70 1.20 4.95 5 11 9 34 24 6 16 2.69 1.22 6.12 6 10 7 35 25 6 17 2.69 1.46 5.13 7 9 10 38 23 5 15 2.58 1.16 4.08 8 12 4 41 21 11 11 2.58 1.40 3.88 9 3 6 36 29 11 10 2.64 1.04 n.d. 10 8 7 32 27 11 15 2.62 1.39 4.58 1 1 9 6 33 25 11 16 2.60 1.7 6 4.69 12 10 7 38 21 8 16 2.64 1.72 4.58 13 9 8 38 23 7 15 2.66 1.63 4.70 14 8 10 32 27 9 14 2.67 1.72 4.49 . 15 13 7 30 21 12 17 2.68 2.01 5.10 16 10 6 38 27 9 10 2.60 0.82 3.15 17 9 9 35 26 7 14 n.d. 1.42 5.61 18 11 7 41 23 8 10 2.60 0.86 19 11 9 36 25 9 10 2.61 0.96 2.00 20 8 10 37 26 9 10 2.66 0.67 3.30 21 12 9 38 24 9 8 2.60 0.95 3.42 22 8 10 37 19 10 16 2.64 1.81 5.86 25 8 8 43 21 8 12 2.62 1.42 4.53 24 8 9 45 18 6 12 2.62 1.13 5.28 25 9 11 40 21 8 11 2.67 1.50 3.51 26 15 9 39 19 6 12 2.58 1.0 1 3.08 27 12 9 34 23 13 9 2.60 1.30 3.10 28 13 7 32 26 12 10 2.62 1.16 3.05 29 12 8 27 26 9 18 2.65 1.50 4.19 50 48 7 9 10 10 16 2.65 1.46 4.07 31 47 7 3 11 9 23 2.62 2.08 5.28 32 20 10 25 23 8 14 2.61 0.96 3.07 33 20 11 29 21 9 10 2.61 0.86 2.96 34 22 10 24 22 9 13 2.60 0.96 3.08 35 47 8 11 14 8 12 2.62 n.d. 3.08 36 63 8 5 9 4 11 2.64 n.d. 2.87
48 A. Firek
D IS C U S S IO N OF R E S U LT S E X T E R N A L S U R F A C E A R E A
Values of the external area obtained by the glycerol method (Q z ) and those computed from the mechanical analysis (Q z l, equation 6) are correlated, the correlation index r = + 0.49 being significant at the P = 0.99 level. The low correlation coefficient between the two sets of values is the result of differences in the origin of the analysed soil samples.
In the average, somewhat higher values w ere obtained by the com putation method (35.2 m 2g -1) than by the glycerol method (33.4 m^g-1). The ratio of external surface area values computed from mechanical analysis (equation 6) to that obtained by the glycerol method is 1.12 in the average, but oscillates in w ide limits, between 0.64 and 1.84. The mean arithmetic deviation from the quoted mean value of this ratio is 0.18, the mean square deviation being 0.25.
The comparatively small differences between the values of external surface area obtained by both methods deserve attention in the case of samples 1-14 (Tab. 2) as these represent soils with similar geological origin (loess-like fine sand). Soils with other geological provenience of the parent rock showed much greater differences.
T O T A L S U R F A C E A R E A
The highest values of total surface area w ere obtained b y the glycerol method (ßc, Tab. 2), 63.0 m 2g -1 in the average, the lowest ones— -from the sorption of a monomolecular w ater layer N H (_Qcl, equation 2), 48.7 m 2g -1 in the average. The values of total surface area with best approximation to those obtained b y the glycerol method were given by computing this area from a bimolecular w ater layer (ßc3, equation 3), 56.1 m 2g -1 in the average (Tab. 2).
The values of the total surface area determined by the method of water adsorption are correlated with the respective values obtained by the glycerol method. The correlation indices between values obtained by the glycerol method and those obtained from the other methods are significant at a 0.99 level and are as follows:
for minimum hygroscopicity equation 2) r = + 0.51, for maximum hygroscopicity (equation 3) r == + 0.74, for bimolecular water layer (equation 4) r = + 0.53. The ratio of values of total surface area obtained b y the water ad sorption method to those obtained by t'he glycerol one was, respectively:
Comparison of simple methods.. 49
T a b l e 2 2 - 1
Values of surface area of soils in m g determined, by various methods
Surface External Total Internal
Method comput. cerolgly cerolgly water adsorption gly cerol
relative to total
by Symbol Я Z l Q z Q cl ß c2 Q c3 S? w cerolgly ^^\^Formula No. Sample K o > \ ^ ^ 6 - - 2 3 4 -1 50.4 36.0 64.2 32,7 51.9 61.5 28.2 0,44 2 29.8 25.7 61.0 28.4 28.9 44.3 35.3 0.58 3 33.9 34.8 42.9 33.9 n.d« n.d. 8.1 O.I9 4 40.0 41.6 46.9 46.7 64.1 73.1 5.3 0.11 5 39.0 44.6 82» 0 47.5 79.4 95,5 37.4 О.45 6 41.1 32,2 110.2 56.7 66.6 7 1.5 78.0 0.70 7 38.0 35,8 94.0 45.9 52.9 57.0 58.2 0.62 8 33.3 3°. 8 43.5 54.5 50,3 48.5 6.7 0.I5 c; 31.4 26.7 68.3 40.5 n.d. n«d. 41.6 0.61 10 40.9 36.2 52.I 54,0 56.8 58,3 I5.9 0.30 i i 44o2 44,8 76.2 68.5 60.9 57,1 31.4 0.41 12 41,4 З1 .4 81.9 67.0 59,5 55.7 50.5 C.62 13 37.8 35.0 IO5.7 63.4 n.d. n.d. 69.9 0.66 14 37o2 34.0 95.0 67.0 53.1 54.0 61.0 0.64 15 43,2 27.4 92.О 78.0 66.0 61.2 64.6 0.85 16 30.5 20,0 55,6 32,0 40,8 45.4 35.6 0.64 17 n.e. 37,1 106.6 55.2 72.7 81.5 69.5 0.62 18 29.7 24.2 34.8 33.5 n.d. n.d. 10.6 0.30 19 30.3 21.4 27.0 37.4 36.3 35.8 5 .6 0,21 20 30.0 ie.o 50.0 26.1 42.8 5 1 .З 12.0 0.40 21 26.5 35.6 З9 .9 37.0 44.3 48.2 4.3 0.10 22 40.9 30.5 89.8 70,5 76.1 79.0 53.3 0.60 23 33.3 52,0 57,3 55,2 58.8 60,6 5.3 0.09 24 32,9 42,2 54.9 44.0 68.9 80.9 12.7 0.26 25 30.6 28.2 57.1 50.5 45.5 43.I 28.9 O.5I 26 32.1 29.6 47,2 39.3 40,0 40.3 I7 .6 0.37 27 30,2 29,6 3 1.O 5О .5 40.3 35.1 1.4 O.O5 23 31.7 33.0 33.0 45.I З9.5 36.8 0.0 0.00 29 44,6 24,2 57.0 58.3 54.4 52.7 32.8 0.58 30 42,2 36.5 69.3 56.7 52,7 5О.9 32.8 О.47 31 36.7 52.О 75.4 37,7 39.8 56.6 43.4 0,57 32 29.4 28.0 54.5 33,5 38.4 41.0 26.5 0.49 33 35.2 32.8 50,4 37.4 40.0 41.4 17.6 0,37 34 ЗО.6 26.6 79.9 n.d. n.d. n.d. 53.3 0,67 35 24.4 26.6 32,9 n.d. n.d. n.d. 6,0 0.18
total area from equation 2 л л
--- —--- average 0.84, limits 0.48-1.64, total area from glycerol method
total area from equation 3 л ^ „
--- average 0.90, limits 0.48-1.43,
total area from glycerol method Roczniki G lebozn aw cze — 4
50 A. F irek
total area from équation 4
--- average 0.94, limits 0.57-1.71. total area from glycerol method
The mean arithmetic deviations from the mean value of the discussed ratio amounted to 0.23 for equation 2, and 0.24 for equations 3 and 4. The mean square deviations amounted to 0.30, 0.27, and 0.29, respectively.
IN T E R N A L S U R F A C E A R E A
The values of the internal surface area obtained b y the glycerol method fall between 0.0 and 78.0 m2g -1 (Tab. 2). The internal surface area estimated from the results obtained by water adsorption and com puted from equations 2, 3, and 4 as w ell as the external surface area computed by equation 6 from the mechanical analysis gives results which often are several times smaller or larger than those obtained by the glycerol method (Tab. 2).
The values of the internal surface area are correlated with the d if ferences between values of the total surface area obtained by the glycerol method and by the w ater adsorption methods.
In soils with small internal areas the values of total areas obtained by water adsorption are always larger than the respective values obtained by the glycerol method. Again, in soils with large internal surface areas the glycerol method gives larger values of the total area than the water adsorption method.
The values of the differences total surface area measured by the glycerol method minus total area measured by the water adsorption method oscillate within w ide limits and are, respectively :
for equation 3 from — 19.5 to + 53.5 m 2g _1, for equation 3 from — 18.2 to + 43.6 m 2g -1, for equation 4 from — 26.2 to + 41.0 m2g -1 .
Between the internal surface area and the values of these differences there is a strict correlation, and the correlation indices significant at the P = 0.99 level are, respectively:
for equation 3 from — 19.5 to -f 53.5 m 2g _1, for equation 3 from — 18.2 to + 43.6 m 2g _1, for equation 4 from — 26.2 to 4- 41.0 m 2g _1.
The values of the discrepancies between values of the total surface area obtained by the discussed methods may be estimated (when the in ternal surface area is 'known) from the regression equations and the lines draw n from these equations, as shown in Fig. 1.
Comparison of simple methods.., 51
^ C Q С 1.23
[n z/gj
Fig. 1. Influence of internal surface area Q w on the values of differences between the total surface area determ ined by the glycerol method Q c and the computed values: from minimum hygroscopicity. N H — Q c l, from m axim um hygroscopicity
M H — Qc2, and from the bim olecular w ater layer M H — N H i.e. Qc3
C O N C L U S IO N S
1. The estimation of the external surface area of soils could be made from mechanical analysis (by equation
6
) on the condition of applying an adequate numeric coefficient, depending on the origin of the parent rock.2. A comparison of the external surface area obtained by the gly cerol method and that obtained from equation
6
may be utilized as a part-wise information on a similar or a dissimilar geological prov enience of compared soils.3. Values of the total surface area obtained by the water adsorption method largely differ from respective values obtained by the glycerol method.
4. The discrepancy between total surface area values obtained by the glycerol method and b y the water adsorption method was signifi cantly influenced b y the internal surface area.
REFERENCES
[1] D i a m o n d S., К i n t e r E. B.: Surface areas of clay minerals as derived from measurements of glycerol retention. Clays and Clay M inerals, Proc. Vth Nation. Conf. 1956, Washington D. C. Nation. A cadem y of Sei., 1958, 334-348.
52 A. F irek
[2] D m i t r i e w E. A.: M atem aticzeskaja statistika w poczw ow iedienii. Moskwa, Izd. Moskowsk. U niw iersitieta, 1972, s. 263.
[3] K i n t e r E. B., D i a m o n d S.: G ravim etrie determ ination of m onolayer com plexes of clay minerals. Clays and Clay Minerals, Proc. V th Nation. Conf. Washington D. C. 1958, Nation. Academ y of Sei., 1956, 318-334.
[4] K i n t e r E. B., D i a m o n d S.: Pretreatm ent of soils and clays fo r m easure ment of external surface area by glycerol retention. Clays and Clay Minerals, Proc. V H th Nation. Conf. 1958, London, Pergam on Press, 1960, 125-135. [5] K o u z o w P. A.: Osnowy analiza dispiersnogo sostawa prom yszlennych pylej
i izm iełczennych m atieriałow . Leningrad, Izd. Chim ija, 1971, 278.
[6] L e w P. F.: Fiziczeskaja chim ija w zajm od iejstw ija w od y s glinam i. In m ono graph: Tierm odinam ika poczwiennoj w łagi. Leningrad, Izd. Gidrom eteo, 1966, 372-430.
[7] M i c z u r i n B. N.: K oliczestw iennaja zawisim ost’ wsasyw ajuszczew o daw lenija ot sodierżanija dostupnoj w ła gi pri razlicznoj w ieliczin e udelnoj pow ierch- nosti poczw. F izika i B iofizika Poczw , Sbornik trudow po agronomiczeskoj fizik ie, Leningrad, V O L A S N , 19, 1969, 51-58.
[8] S i r o t k i n V. M., G i n z b u r g M. R.: Ob opriedielenii udielnoj powierchnosti dispiersnoj sriedy. Poczw ow iedien. 2, 1971, 158-163.
[9] S c h w e r t m a n n U. : Der Mineralbestand der Fraktion < 2 м. einiger Böden aus Sedimenten und seine Eigenschaften. Zeitschr. f. P fl. Ern. Düng. B oden kunde 94 (139), 1961, 3, 209-227.
[10] Untersuchungsmethoden des Bodenstruktur-Zustandes. Berlin, VEB Deutscher Landw irtschaftverlag, 1968, s. 503.
[11] W o r o n i n A . D., W i t i a z j e w V. G.: К ocenkie w ieliczin y wniesznoj i wnu- triennoj udielnych powierchnostej tw ierdoj fa zy poczw po izotierm am de- sorpcii parów wody. Poczw ow iedien. 10, 1971, 50-58.
A . Ф И Р Е К С Р А В Н Е Н И Е Н Е С Л О Ж Н Ы Х М Е ТО Д О В О П РЕ Д Е Л Е Н И Я У Д Е Л Ь Н О Й П О В Е Р Х Н О С Т И П О Ч В Институт Почвоведения, Агрохим ии и М икробиологии Сельскохозяйственной Академии в Кракове Р е з ю м е И сследовали 36 почвенных образцов представительных д ля следую щ и х материнских пород: а — лессовидная пы левая порода из В еличского П ред горья, b — выветренный материал ф ли ш евы х песчаников из окрестности го рода К альвари я и с — прослоенная пы левая порода из окрестности Тенчинека. Развернуты е площ ади определяли по глицеринному методу, а такж е и счисляли на основании сорбции воды и механического состава с помощью уравнений (2), (3), (4) и (6) приведенных в тексте. Установлено, что: 1. Величины внешних поверхностей определенные по глицеринному методу и вы чи слен и е с помощью уравнения (6) показывали, в среднем небольш ие раз личия. Это в частности касается почв образованых из лессовидны х п ы лев ы х формаций (образцы 1-14 в табл. 2). Уравнение (6) м огло бы бы ть такж е исп
оль-Comparison of simple methods.., 53 зовано для оценки внешней поверхности, если бы можно бы ло подобрать числовой коэффициент обусловленны й величиной зерен. В случае ж е извест ной величины внешней поверхности, определенной например по глицеринному методз1', ее сравнение с величинами полученны ми с помощью уравнения (6) может дать информацию о таком ж е или разном геологическом происхож дении почвенного материала. 2. Наивысшие величины общей площ ади бы ли п олучен ы по глицеринному методу, а наинисшие по методу сорбции моном олекулярного слоя воды — уравнение (2). Наиболее приближ енны е к глицеринному методу величины об щей площ ади бы ли получен ы путем вы числения этой величины на основании м олекулярн ого слоя воды с помощью уравнения (4) (табл. 2). Разли чи я м еж ду величинами общей площ ади полученны ми по глицерин ному методу и величинами вы численными с по’мощью уравнений (2), (3) и (4) бы ли неоднократно значительными (до около 50 ж2/г-1 ) и тесно связаными с величиной внутренней поверхности. A . F IR E K C O M P A R A IS O N DE S IM P L E S M ÉTH O D ES PO U R D É T E R M IN E R L A S U R F A C E T O T A L E DES SO LS
Institut de Pédologie, Chim ie A grico le et M icrobiologie, U niversité Agronom ique de Cracovie
R é s u m é
36 échantillons de sols furent analysés; ils représentent les roches-mères sui vantes: a — lim on loessoïde des collines de W ieliczka, b — produit d ’altération de grès carpatiques des environs de K alw aria, с — lim on stratifié des environs de Tenczynek. Les surfaces totales furent déterminées par la méthode à glycérine, ainsi que calculées à partir de l ’adsorption d’eau et de la composition mécanique d’après les équations (2), (3), (4), (6) (voir texte).
On a constaté ce qui suit:
1. Les valeurs des surfaces extérieures, soit obtenues par la méthode à g ly cérine, soit calculées d’après l ’équation (6), en moyenne ne d ifféraien t que peu. Cela concerne spécialement les sols form és sur limons loessoides (échantillons 1-14, table 2). L ’équation (6) pourrait servir à estimer la surface extérieure à condition de choisir un coefficient approprié qui dépendrait de la form e des particules du sol. Si, par contre, en connait la valeur de la surface extérieure (obtenue par exem ple à l ’aide de la méthode à glycérine), sa comparaison avec les chiffres calculés d’après l ’équation (6) peut inform er sur l ’origine géologique du m atériel du sol (soit la même ou bien différente).
2. Les valeurs les plus élevées de surface totale ont été obtenues par la m é thode à glycérine, les plus basses — par la méthode d’adsorption d’une couche m onom oléculaire d’eau (équation (2)). Les valeurs de surface totale, les plus proches de celles qu’on obtient par la méthode à glycérine, ont été calculées d’une couche bim oléculaire d’eau d’après l ’équation (4) (table 2).
Les différences entre les valeurs de surface totale obtenues par la méthode à glycérine et celles qui ont été calculées d’après les équations (2), (3), (4), étaient souvent considérables (jusqu’à environ 50 m 2 g - 1) et strictem ent corrélées avec la valeur de la surface intérieure (fig. 1).
54 A. Firek
A. F IR E K
V E R G L E IC H V O N E IN F A C H E N M E TH O D E N
F Ü R B E S T IM M U N G DER G E S A M T O B E R F L Ä C H E V O N BÖDEN Institut für Bodenkunde, Agrikulturchem ie und M ikrobiologie,
Landw irtschaftliche U niversität zu K ra k ów
Z u s a m m e n f a s s u n g
Es wurden 36 Bodenproben untersucht; sie repräsentieren folgende M u tter gesteine: a) — lössartiger feinsandiger Schluff aus dem W ieliczkaer Vorgebirge, b) — Verw itterungsm aterial von Flyschsandsteinen aus der Um gebung von K alw aria, und c) — geschichteter feinsandiger Schluff aus der Um gebung von Tenczynek. D ie Gesamtoberflächen wurden m it der G lyzerin-M ethode erm ittelt; sie wurden auch auf Grund von Wasseradsorption und K orngrössenverteilung berechnet — nach den Gleichungen (2), (3), (4), (6) (siehe Text).
Es wurde folgendes festgestellt:
1. Die W erte der Aussenoberflachen, m it der G lyzerin-M ethode bestim m t oder aus der Gleichung (6) berechnet, w aren im M ittelw ert nur w en ig voneinander unterschiedlich. Dieses b e trifft insbesondere Böden auf lössartigem feinsandigem S chlu ff gebildet (Proben 1-14 in Tab elle 2). D ie Gleichung (6) könnte zur A b schätzung der Aussenoberfläche dienen, wenn es möglich ist, einen geeigneten Z ah lenkoefficient zu wählen, der von der Korngestalt abhängig ist. Dagegen, wenn die Grösse der Aussenoberfläche bekannt ist (zB. m it der G lyzerin-M ethode b e stimmt), dann kann ihr Vergleich m it den W erten, die von Gleichung (6) stammen, über geologische Abstam m ung (ob dieselbe oder unterschiedliche) des Bodenm a terials Auskunft erteilen.
2. D ie höchsten W erte der Gesam toberfläche von Böden wurden m ittels der G lyzerin-M ethode erhalten, die niedrigsten dagegen — m ittels der W asseradsor ptionsmethode (Monomolekulärschicht), Gleichung (2), Die Gesamtoberflächengrössen, die am nähesten deren der G lyzerin-M ethode w erte lagen, wurden durch B e rechnung dieser W erte aus einer Bim olekularschicht erhalten (Gleichung (4), T a belle 2).
Die W erte der D ifferen zen zwischen den Grössen der Gesamtoberfläche, die m it der G lyzerin-M ethode gemessen waren, und denen, die aus den Gleichungen (2), (3), (4) berechnet waren, waren o ft erheblich (bis etw a 50 m 2g - 1) und eng m it den Grössen der Innenoberflächen verbunden (Abb. 1).
A . F IR E K
P O R Ó W N A N IE P R O S T Y C H M E TO D O Z N A C Z A N IA R O Z W IN IĘ T E J P O W IE R Z C H N I G LE B
Instytut Gleboznawstwa, Chem ii Rolnej i M ik rob iologii A kadem ii Rolniczej w K ra k ow ie
S t r e s z c z e n i e
Zbadano 36 próbek glebow ych reprezentujących skały m acierzyste: pył lesso- podobny z Pogórza W ielickiego, zw ietrzelin y piaskowców fliszow ych z okolic K a l w arii oraz pył w arstw ow any z okolic Tenczynka. Pow ierzch n ie rozw inięte ozna
Com parison of simple methods... 55
czono metodą glicerynow ą oraz w yliczono na podstawie sorpcji w ody i składu mechanicznego w edług równań (2), (3), (4) i (6), podanych w tekście.
Stwierdzono, że:
1. wartości pow ierzchni zewnętrznych uzyskanych metodą glicerynow ą i w y liczone w zorem (6) średnio różniły się nieznacznie. Szczególnie dotyczy to gleb w y tworzonych z pyłów lessopodobnych (próbki 1-14 w tab. 2). Rów nanie (6) m ogłoby być stosowane do oceny powierzchni zew nętrznej, jeśli byłoby można w ybrać w ła ś ciw y współczynnik liczbow y zależny od kształtu ziarn. Jeśli natomiast znana b y łaby wielkość powierzchni zewnętrznej, oznaczona na przykład metodą glicerynową, to porównanie je j z w artościam i uzyskanymi równaniem (6) może stanowić in fo r m ację o takim samym lub różnym pochodzeniu geologicznym m ateriału glebow ego;
2. najw yższe wartości pow ierzchni całkow itej uzyskano metodą glicerynow ą, a najniższe metodą sorpcji jednom olekularnej w arstw y w ody — rów nanie (2). N a j bardziej zbliżone do m etody gliceryn ow ej w ielkości powierzchni całkow itej uzyska no w drodze w yliczen ia tej wartości z dwum olekularnej w arstw y w ody — ró w n a niem (4) (tab. 2).
W artości różnic m iędzy w ielkościam i powierzchni całkow itej, otrzym anym i m e todą glicerynow ą a w yliczon ym i równaniam i (2), (3) i (4), były często znaczne (do ok. 50 m ^ - 1) i ściśle związane z wielkością powierzchni w ew nętrznej (rys. 1). D r A d a m F ir e k
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C h e m ii R o l n e ) i M ik r o b io lo g ii A . R. K r a k ó w , ul. M ic k ie w ic z a 30
