Characterization Of Soil Properties Research Articles

Geographical distribution of selected soil fertility parameters of inland valleys in West Africa

This study was part of an ongoing characterization of soil properties of inland valleys (IVs) of West Africa. Soil sampling was done during 1982 to 1989. Soil properties of the topsoil (0–15 cm) were used to evaluate the fertility status of the various geographic regions. Large differences in soil fertility parameters were observed in the various geographic regions. Generally the drier regions [Sudan (SuS) and Sahel savannas (SS)] were relatively higher in ECEC [SuS, 7.7 cmol(+) kg −1 and SS, 8.2 cmol(+) kg −1, topsoil means] and exchangeable basic cations; but total C (SuS, 5.5 g kg −1 and SS, 6.2 g kg −1, topsoil means) and total N (SuS, 0.68 g kg −1 and SS, 0.66 g kg −1, topsoil means), available P (SuS, 2.6 mg kg − 1 and SS, 2.7 mg kg −1, topsoil mean) and exchangeable acidity [SuS, 0.14 cmol(+) kg −1 and SS, 0.46 cmol(+) kg −1, topsoil means] were relatively low. Soil fertility parameters were generally low in the Guinea savanna zone [ECEC, 2.5 cmol(+) kg −1; total C, 7.3 g kg −1; total N, 0.7 g kg −1 and available P, 2.9 mg kg −1, topsoil means]. In the Forest region, ECEC [5.7 cmol(+) kg −1], exchangeable Ca [2.3 cmol(+) kg −1], Mg [1.24 cmol(+) kg −1], acidity [1.67 cmol(+) kg −1], and total C (20.4 g kg − 1 ) and total N (1.66 g kg −1) were relatively high. Available P (5.3 g kg −1 ) and exchangeable K [0.27 cmol(+) kg −1] were relatively moderate. However, in the more wetter Equatorial Forest, available P and exchangeable K were low and acidity very high. Soil properties of these inland valleys were affected by both geology and climate. Geological formation of recent alluvial deposition, rejuvenation and the presence of basic rocks mostly resulted in relatively fertile soils while soils of very old geological origin were relatively less fertile. Climate had a dual effect on these soil properties: within the areas with tropudic and typic udic soil moisture regimes, serious leaching resulted in less exchangeable basic cations but high exchangeable acidity; however, rainfall enhanced high biomass production which resulted in relatively high organic matter content and hence high ECEC and total N. Annual burning, especially of the grass vegetation in savanna area brought about a low addition of plant residue into the soil. Total elemental oxides were almost the same for all the zones. However, values for the various sites were different due to differences in geological formation. The relative differences in retention (ECEC) and leaching of basic cations resulting from weathering also accounted for some of the differences in the soil fertility properties observed.

Characterization of soil properties from large scale load tests : Gatti, G; Cividini, A; Galloni, G Proc 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, 26–30 May 1991V1, P402–412. Publ Rotterdam: A A Balkema, 1991

Characterization of soil properties from large scale load tests : Gatti, G; Cividini, A; Galloni, G Proc 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, 26–30 May 1991V1, P402–412. Publ Rotterdam: A A Balkema, 1991

Soil properties relevant to land degradation in abandoned sloping fields in Aisa valley, Central Pyrenees (Spain)

A multi-approach characterization of soil properties in abandoned fields in the Aisa valley, at mid mountain in the Central Spanish Pyrenees, demonstrated that the soil's own peculiar characteristics are concerned with conservation problems. Aggregate stability and shrinkage tests pointed to a relatively good soil performance due to the aggregating role of organic matter and calcium carbonates, although calcium ions, in some instances, may exert and additional antagonistic role for a sealed surface, increasing runoff. On the other hand, soil micromorphology suggests that the poor condition of the soils is in some contradiction to paedogenic activity. These findings, together with the presence of ashes, support the hypothesis that land degradation in these areas is mainly related to human activity thought unsuitable management after land abandonment.