Investigations of the quantity and behaviour of variable positive charges in soils of temperate climatic zone were conducted. The experiments were carried out using sodium forms of clays separated from selected acidic soils of different origin. The clay fractions investigated possess considerable quantities of positive charge connected with mineral components surfaces. It was noted that organic matter presence leads to a considerable decrease of positive charge even when the positive charge observed after organic matter removal was rather high so the organic colloidal particles strongly block the positive charge probably by electrostatic bonds. A linear relationship between iron oxide charge and surface area was obtained.
An examination of negative charge distribution among solid soil phase components and its relations to pH of the equilibrium solution was conducted by model experiments on clays separated from selected acidic soils. It was noted that negative charge blocking by iron and aluminium oxides occurs, with the most pronounced effect in brown and podzol clays. On the basis of measured values of sample charges before and after removal of organic matter the organic matter charges were calculated to have a more linear pH dependence than that seen for natural clays. This effect is attributed to the presence of positive charges in the clays investigated.
In the years 1987-1992 field experiments were carried out in five commercial orchards in Poland, growing on acid soils. In these orchards herbicide fallow was kept in the rows of trees and grass between them. In spring 1987, the whole surface of the experimental fields was treated with differentiated doses of calcium (from 750 to 2500 kg CaO/ha). The liming was repeated in spring 1990. The control fields were not limed. Before the beginning of the experiment, i.e. in 1986 and again in 1992 soil samples were taken separately from under the grass and herbicide fallow from the arable and sub-arable layer. The soil in the herbicide fallow strips had lower pH and higher content of available phosphorus and potassium than in grass strips. The content of available magnesium was similar both under grass and herbicide strips. In the soil kept as herbicide fallow and non-limed a distinct decrease in pH and magnesium content occurred within six years of the study. Such process did not take place in soil under grass. Liming caused the increase in soil pH more distinctly under grass than in herbicide strips. The increase in magnesium content was similar in both ways of soil management. Liming did not influence the phosphorus and potassium content under grass and herbicide fallow. The magnesium content lowered as a result of liming, both under grass and in herbicide strips but in sub-arable layer only.
The influence of pH and aluminium on soil clays’ negative charge was investigated for clays separated from acidic soils of different origin. It was observed that aluminium caused a negative charge decrease due possibly to nonexchangeable Al polycations adsorption in the 4-6 pH range. Aluminium complexing by organic matter can diminish soil negative charge in a broad range of pH.
The behaviour of exchangeable aluminium and hydrogen in the broad range of pH was studied at model conditions on clays taken from acidic soils of different origin. Sodium and aluminium forms of clays were used and ion exchange experiments were performed. On the basis of the results obtained and data previously reported, it was calculated that exchangeable aluminium below pH 4 is trivalent and in the pH range between 4 to 6 its average charge decreases. Measurable, exchangeable hydrogen quantities occur only at very low pH values.
Wybrano odmiany jęczmienia jarego, które z natury lepiej plonują w warunkach gleby lekkiej i niskiego pH. Badano również wpływ wapnowania i nawożenia Mo na plony i skład chemiczny tych odmian. W kolejnych 3 latach prowadzono ścisłe dwuczynnikowe doświadczenia polowe na glebie lekkiej o odczynie kwaśnym lub bardzo kwaśnym. Stwierdzono, że niektóre odmiany są dobrze dostosowane do warunków gleb zakwaszonych i plonują lepiej, niż pozostałe. Wapnowanie nie wpłynęło na wzrost plonów jęczmienia, a w przypadku jednej odmiany wywołało negatywny efekt. Nawożenie Mo powodowało wzrost plonu tylko w nielicznych przypadkach. Oba zabiegi wpływały na wzrost zawartości Mo w pędach i ziarnie z jednoczesnym obniżeniem koncentracji Mn, przy czym wapnowanie w większym stopniu niż nawożenie Mo.
Badano przyswajalne makroskładniki (Mg, K20, P205) i odczyn w górskich glebach ornych (brunatne kwaśne) w ciągu 26. lat. Gleby gliniaste o pHKCl 4,4 są średniozasobne w magnez, zawierają średnio 5,7 mg Mg ■ 100 g-1 gleby w warstwie ornej. Zawartość magnezu w glebie jest dodatnio skorelowana z iłem koloidalnym i z częściami spławialnymi. Zawartość potasu w glebach wynosi średnio 15,4 mg K20 • 100g-1. Wzrost areału wysokozasobnych gleb w potas stwierdzono po zwapnowaniu gleb (po II rotacji). Stan niskiej zasobności w fosfor utrzymywał się w ciągu całego okresu - średnia zawartość P2O5 wynosiła 4,7 mg • 100 g-1 gleby. Niska zasobność w fosfor wiąże się głównie z bardzo kwaśnym odczynem gleb (pHkCl do 4,5) na ponad 70% areału gleb ornych. Poprawa zasobności gleb brunatnych kwaśnych w przyswajalne makroskładniki wymaga zmniejszenia areału gleb bardzo kwaśnych.
The relationships between base saturation (BS) and pH were evaluated basing on three different definitions of degree of base saturation: expressing BS in terms of the total (pH 8.2), ‘effective’ and ‘actual’ cation exchange capacities. The first two approaches lead to differentiation of BS/pH curves for different cationic as well as solid phase compositions (presence of organic matter) of exchange complex. The third approach differentiated soils only in respect to cationic composition.
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