Aluminium and acidity in Finnish soils

Self Cite

Abstract. Effective CEC 0f230 mineral soil samples was estimatedas sum of{Ca-\-Mg) and {AI +H) displaced by N KCI. The mean values as me/100 gof soil were, in the surface samples, 15.9 ± 2.0 in 46 clay soils, 8.9 f 1-3 in 21 silt and loam soils, and 8.3 ± 1.1 in 39 sandy soils. In samples from the deeper layers the corresponding means were 16.3 ± 2.3 in 54 clay soils, 5.6 ± 0.9 in 21 silt and loam soils, and 2.5 dr 0.5 in 49 sandy soils.In surface samples of clay soils the mean effective CEC was about two thirds, in sandy soils of deeper layers about one third, and in all other groups about one half of the corresponding average potential CEC determined by neutral ammonium acetate.In the total material in which clay content ranged from 0 to 95%, organic C from 0.1 to 8.7 %, soil pH from 3.3 to 7.5, and oxalate soluble Al from 1.4 to 47.9 mmol/100 g, the » effective CEC» depended mostly on clay content: the partial correlation coefficient r o.9o***, and the standard partial regression coefficient ft = 0.84. The corresponding coefficients for the relationship between the »effective CEC» and the content of organic C were r = o.ss*** and p = 0.29, soil pH r = o.3s*** and P = 0.16, and oxalate soluble Al r -0.13 and P -0.06.The positive effect of liming on effective CEC, particularly, in coarser textured acid soils high in organic matter was emphasized.The figure for the cation-exchange capacity (CEC) of a soil largely depends on the method used for its determination, particularly on the pH of the saturating electrolyte solution (Pratt and Bair 1962, Bhumbla andMcLean 1965). In Finnish more or less acid soils estimation of CEC at pH 7, or even at pH 8.2 as by the Mehlich method, is likely to yield markedly higher values than is the exchange capacity of these soils as they exist in the field. This is the case especially with soils low in clay and high in organic matter, since the CEC of organic matter is almost completely pH-dependent (Helling et al. 1964). It is also likely that in our acid soils aluminium-hydroxy-polymers block part of the exchange sites of organic and inorganic colloids, in this way decreasing the effective CEC of the soil (Keränen 1946, Kaila 1971.

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Effective cation-exchange capacity in Finnish mineral soils

Kaila

1971

Self Cite

“…The contents of Ca and Mg in the extract were determined by AAS and that of K by flame photometry. The exchange acidity (AI + H) was extracted with 1 M KCI and titrated with 0.01 M HCI (KAILA 1971). Table 1.…”

Section: Methodsmentioning

confidence: 99%

Effect of liming and N fertilization on growth, macronutrient content and uptake by mixed stands of three clovers and timothy

Jokinen

1985

Mixed stands of clovers and timothy grew well in unlimed (Ca0) acid soil (pH(CaCl2) 4.8). The highest total yield of red clover-timothy was obtained at a low lime level (Ca1 = 12g /pot CaCO3). The yield of red clover alone responded to liming similarly. The reducing effect of N fertilization (2000 mg/pot N as NH4NO3) on the yield of clovers was greatest in the first growing season (cuts 1 to 4) without lime, and in the second growing season (cuts 5 to 7) with lime (Ca1 = 12g /pot, Ca2 = 24g/pot). Liming without N fertilization promoted the growth of timothy only in the two first cuts; N fertilization increased the yield at all lime levels. Liming increased the Ca content of clovers, but there were no differences between lime levels. Mg and K showed a decreasing trend. N fertilization did not affect the nutrient content of clovers. A good quality of clover yield reguired adequate amounts of other fertilizations than N. In timothy, the Ca content increased slightly at all lime levels; the N and K contents increased by N fertilization. The N uptake by red clover was highest at the Ca, level, by white clover and alsike clover at the Ca0 level. The proportion of clover was larger than that of timothy of the uptake of N, P, Ca and Mg. When N was applied, the uptake of K showed an opposite direction.

“…In determination of exchangeable cations and effective cation-exchange capacity of soil, exchangeable cations are commonly extracted by successive treatments with unbuffered neutral salt solutions like 1 M KCI (e.g. Yuan 1959, Kaila 1971b, 1971c, Niskanen and Jaakkola 1986. The normal practice, four or five successive extractions, presupposes a laborious multiphase shaking and centrifugation procedure.…”

Section: Introductionmentioning

confidence: 99%

Number of extractionsin determination of effective cation-exchange capacity

Niskanen

1986

The number of successive extractions with 1 M KCI needed for adequate estimation of effective cation-exchange capacity was studied with four mineral soils. The effective CEC estimated as the sum of equivalents of exchangeable Ca, Mg, Na, H and Al extracted by four successive treatments ranged from 57 to 206 meq/kg soil. In three cultivated soils, 63—90 % of CEC was saturated by Ca and Mg, in the fourth soil (a deeper layer virgin soil), 60 % of CEC by exchangeable H and Al. By two successive treatments often minutes duration with 50ml of 1 M KCI, the equivalent sum of exchangeable cations extracted amounted to 83—92 % of effective CEC in cultivated soils and 67 % of that in virgin soil; >90 % of exchangeable Ca and Mg, 78—97 % of Al, 48—62 % of H and 28—64 % of Na were extracted. By three successive treatments the equivalent sum amounted to 79—96 % of effective CEC, by the single treatment of 30 minutes duration with 100ml of 1 M KCI to 57—79 %. Two successive extractions with 1 M KCI may be enough for estimation of effective CEC in cultivated mineral soils with high degree of saturation by exchangeable Ca and Mg. Soils with high degree of saturation by exchangeable acidity require three successive extractions.