The Potassium Status of Soils in the Savanna Zone of Nigeria

1971 ◽  
Vol 7 (3) ◽  
pp. 257-270 ◽  
Author(s):  
A. Wild

SUMMARYThirty one soils from the Savanna Zone of Nigeria were low in exchangeable potassium, ΔK°, and ΔK°° and had very low potassium buffer capacities. The soils were low in clay, which was kaolinitic. Two soils high in 2:1 layer clay minerals contained higher quantities of labile potassium. Total potassium varied with parent material. Release of non-exchangeable potassium was low. After cropping, wet/dry cycles released exchangeable potassium. Potassium deficiency is expected to occur commonly with intensive cropping in the field.

Soil Research ◽  
1975 ◽  
Vol 13 (2) ◽  
pp. 217 ◽  
Author(s):  
DC MacKay ◽  
JS Russell

Four Queensland soils were intensively cropped by buffel grass, Cenchrus ciliaris, in controlled environment growth rooms at three temperatures. Rates of growth (dry matter production) of tops and roots, of potassium uptake, and of changes in soil potassium properties were examined. With adequate potassium applied, growth rates for 31 weeks were nearly constant at 2.7, 2.6, 2.0, and 2.0 t/ha/week on a brigalow, grey clay, podzolic, and solodic soil, respectively. Without potassium, exchangeable potassium decreased quickly to a nearly common level on all soils, corresponding decreases occurred in the potassium content of tops and roots, and severe deficiencies with restricted yields soon resulted. Without applied potassium, moderate release of non-exchangeable potassium occurred on all soils during the first 4 weeks of cropping (0.10-0.18 m-equiv./100 g). Apparent fixation of potassium resulted in the succeeding 6-9 weeks, and, on the fine-textured soils (brigalow and grey clay) only, further slow release took place during the period of potassium deficiency when growth was slow. The overall release of non-exchangeable potassium by all four soils was small (0.02-0.16 m-equiv.1 100 g). Higher temperatures significantly increased yields of tops and roots, decreased the potassium concentration in the plants, increased the rate of depletion of exchangeable potassium, and had no effect on the release of non-exchangeable potassium. It is concluded that on these soils, particularly the solodic and podzolic, potassium deficiency will occur under intensive cropping.


1958 ◽  
Vol 38 (1) ◽  
pp. 36-43 ◽  
Author(s):  
H. B. McEwen ◽  
B. C. Matthews

The rate of release of non-exchangeable potassium, i.e. potassium-supplying power, of 41 Ontario soils was measured by a continuous percolation procedure. It was found that clay content of the soil was the predominant factor affecting potassium-supplying power (r = 0.978). Potassium fertilization or intensive cropping of the soil caused no change in the potassium-supplying power of the soil. As potassium-supplying power was found to be a constant characteristic of soil and not a function of previous management, potassium-supplying power measurements should not be necessary in routine soil testing. Knowledge of potassium-supplying power can be deduced from particle size distribution. Because soils of different texture have different potassium-supplying power, the interpretation of measured exchangeable potassium in terms of fertilizer requirement will be different for soils of different textural class.


ISRN Botany ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Eri Adams ◽  
Celine Diaz ◽  
Minami Matsui ◽  
Ryoung Shin

Plants have developed mechanisms to adapt to the potassium deficient conditions over the years. In Arabidopsis thaliana, expression of a potassium transporter HAK5 is induced in low potassium conditions as an adaptive response to nutrient deficiency. In order to understand the mechanism in which HAK5 is regulated, the full-length cDNA overexpressor gene hunting system was employed as a screening method. Of 40 genes recovered, At4g18280 was found to be dramatically induced in response to potassium-deficiency and salt stress. Plants overexpressing this gene showed higher HAK5 expression and enhanced growth. These plants were also less sensitive to potassium-deficiency in terms of primary root growth. Taken together, these data suggest that this novel component, At4g18280, contributes to regulation of HAK5 and, consequently, tolerance to potassium-deficiency in plants.


1974 ◽  
Vol 54 (3) ◽  
pp. 255-263 ◽  
Author(s):  
L. D. BAILEY

Continuous cropping of eight Manitoba soils to alfalfa in the greenhouse decreased the exchangeable potassium of the soils to low equilibrium levels. Non-exchangeable potassium was removed from the soils by the alfalfa. The rate of decrease of exchangeable potassium and the quantity of non-exchangeable potassium mobilized was significantly influenced by the addition of ammonium nitrate or urea to the soils. However, there were no significant differences between the soils treated with ammonium nitrate and those treated with urea. There was considerable variation among soils in the rate of decrease of exchangeable potassium and the quantity of non-exchangeable potassium mobilized. The total yield of soil potassium was related to the initial exchangeable potassium levels of the soils. Addition of NH4NO3 increased the percentage of total N in the plant material harvested prior to the eighth harvest. After this eighth harvest the added nitrogen had no effect on the nitrogen content of the harvested material. In general, fine-textured soils yielded more plant material and total potassium, and maintained a higher level of exchangeable potassium than coarse-textured soils.


Clay Minerals ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 699-707 ◽  
Author(s):  
A. Mirabella ◽  
M. Egli ◽  
S. Carnicelli ◽  
G. Sartori

AbstractThe formation of clay minerals was investigated in Spodosols developed in the subalpine belt, with similar exposure, climate and age, but deriving from different parent materials. All the soils were classified as Haplic Podzols and showed the characteristic eluviation and illuviation features of Fe, Al and organic carbon. However, varying parent material lithology led to different clay mineral assemblages in the soil. Smectite could be found in the E horizons of soils developed from granodiorite and tonalite materials. Its formation was strongly dependent on the presence of chlorite in the parent material. If nearly no other 2:1 mineral components, such as chlorite, are present in the lower soil horizons, then a residual micaceous mineral becomes the dominant clay mineral. The latter derives from a mica-vermiculite interstratified mineral.


1960 ◽  
Vol 11 (5) ◽  
pp. 750
Author(s):  
AM Graley ◽  
KD Nicholls ◽  
CS Piper

The potassium status of Frodsley sandy loam and some associated soils from the Fingal district, north-eastern Tasmania, has been investigated. Regularly spaced sampling of surface soils on a rectilinear grid pattern disclosed a variability of exchangeable potassium values in the field much greater than recorded for soils elsewhere; even for 3-ft spacings there was a sevenfold range. The need for adequate sampling of experimental areas is stressed. The median value for exchangeable potassium in the A1 horizon of Frodsley sandy loam was 0.31 m-equiv./100 g for "developed" areas and 0.35 m-equiv./100 g for "undeveloped" areas. Values for the A2 horizon were closely correlated with those for the corresponding surface horizon, but only about one-third as high. The amounts in the B horizon tended to approximate to those in the A1 horizon except for soils with high values in the surface. The potassium-supplying capacity of the soils was assessed by fractionation of the potassium into water-soluble, exchangeable, difficultly exchangeable, hydrochloric acid-soluble, and total potassium. In Frodsley sandy loam approximately 35 per cent. of the exchangeable potassium appeared in the water-soluble form, which suggested that there may be moderate losses from this soil by leaching. Ten minutes' boiling with normal nitric acid released only about 90 per cent. more potassium than was present in the exchangeable fraction. Boiling normal nitric acid extracted much less potassium from some samples of this soil type than did cold normal ammonium chloride from others, because of the great variability of exchangeable potassium. Concentrated hydrochloric acid dissolved a further 0.60.7 m-equiv./100 g on the average. These low values for the two latter fractions are taken to indicate the poverty of this soil type in reserves of potassium and, with the relatively low values for the exchangeable fraction, explain the widespread responses to potassium reported in field experiments. Examination of the minerals of the clay fraction of Frodsley sandy loam supported the chemical data in regard to the poor potassium status of these soils. Separation of sand, silt, and clay from the B horizons of two profiles showed that much of the total potassium was present in the coarser fractions of the soil. Type A, a soil associated with Frodsley sandy loam on river terraces, had a similar potassium status. Soils formed on dolerite were significantly higher in all categories of potassium.


1965 ◽  
Vol 37 (3) ◽  
pp. 195-206
Author(s):  
Armi Kaila

The fixation of added potassium under various conditions was studied using soil samples collected from three layers of ten mineral soils. The type of soil ranged from finesand to heavy clay, the soil reaction from pH 3.3 to pH 6.4 (in 0.01 M CaCl2), and the total potassium content from 1.99 to 3.41 per cent. The fixation against an extraction with neutral ammonium acetate distinctly depended on the conditions used for the application of potassium: on the average, without drying the samples fixed during one hour somewhat more than 80 per cent of the amount fixed during 18 hours, when the samples were treated with KCI-solutions corresponding to 2.5 me K/100 g soil. Drying the suspension at 80°C resulted in a fixation 1.2 to 4.1 times as high as that under the »wet» conditions within one hour. The results of these two methods were not particularly closely correlated (r = 0.73***). The results of the »dry» method were found to be of the same order as the fixation of potassium in samples incubated for three months at room temperature. The results of the »dry» fixation were positively correlated with the pH (r = 0.75***) and negatively correlated with the contents of organic carbon (r = —0.63***) and exchangeable potassium (r = —0.40*), but they were not correlated with the contents of clay or the acid soluble potassium. Under the »wet» conditions the relative fixation generally decreased with an increase in the application of potassium, but there were samples which fixed a rather low but almost equal portion of all the applications from 0.625 to 40 me K/100 g soil. The fixation from the highest addition was correlated with the clay fraction


Clay Minerals ◽  
1979 ◽  
Vol 14 (1) ◽  
pp. 29-37 ◽  
Author(s):  
M. L. Fernandez-Marcos ◽  
F. Macías ◽  
F. Guitián-Ojea

AbstractThe composition of the soil solution of various horizons of Galician soils was studied to gain insight into the direction of the processes of weathering and neoformation by means of stability diagrams of the clay minerals. The soil solution was extracted by compression at various pF values.The most significant results are as follows. In all the cases studied the mineral in equilibrium with the soil solution is a 1:1 philosilicate. As the pF at which the soil solution is extracted increases, corresponding to smaller pore size, pH increases and silica concentration falls. The stable mineral does not vary significantly between different horizons of the same profile. Each parent material gives rise to a different zonation in the stability diagrams. The predictions of the stability diagrams are in general agreement with the mineralogical data of the clays of the horizons in question.Finally, weathering processes in Galicia are briefly commented on.


1981 ◽  
Vol 21 (112) ◽  
pp. 543 ◽  
Author(s):  
AM Graley

Two forms of depletion cropping were examined. Perennial ryegrass was continuously cropped on two contrasting soils in pots. Simultaneously, repeated crops of ryegrass, subterranean clover, and marrow-stem kale were grown by a modified system of depletion cropping in which the whole plant was harvested and the soil sampled before being repotted for further crops. Fractions of soil potassium determined by chemical extractions were compared with the results from depletion cropping. Although the modified system needed added attention, particularly between crops, the available potassium was well exploited because of the thorough mixing of the soil. A further benefit was that the depletion of potassium in soils and plants could be followed progressively. Different root systems of the plant species greatly influenced the total potassium uptake. Reserves of initially non-exchangeable potassium contributed much to the uptake while decrease in soil potassium measured by repeated nitric acid extractions ranged from 63 to 80% of the uptake. Ryegrass with its dense root system was able to take up more non-exchangeable potassium from a yellow podzolic soil than clover and kale.


1977 ◽  
Vol 4 (4) ◽  
pp. 499 ◽  
Author(s):  
CJ Asher ◽  
PG Ozanne

Individual plants in an apparently uniform set of capeweed seedlings were found to differ markedly in susceptibility to potassium deficiency when grown in solution culture at a constant potassium concentration of 2.6 �M. Large differences were found in dry weight of tops (8-218 mg), tissue potassium concentration (0.3 - 4.8 %) and total potassium in the tops (23-10 500 �g potassium). Dry weight and percentage potassium were positively correlated (r = 0.859, P<0.001) at 2.6 �M potassium but not at higher potassium concentrations. The nature and possible exploitation of such variability in cross-fertilized forage plants are briefly discussed.


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