0000000000153286
AUTHOR
J.s.c. Mbagwu
Influence of land use on the characteristics of humic substances in some tropical soils of Nigeria
Summary In highly weathered tropical conditions, soil organic matter is important for soil quality and productivity. We evaluated the effects of deforestation and subsequent arable cropping on the qualitative and quantitative transformation of the humic pool of the soil at three locations in Nigeria. Cultivation reduced the humic pool in the order: acetone-soluble hydrophobic fraction (HE) > humic acid (HA) > humin (HU) > fulvic acid (FA), but not to the same degree at all three sites. The C and N contents, as well as the C/N ratios of humic extracts, were large and not substantially influenced by land use. The δ13C values of the humic extracts were invariably more negative in forested soil…
Comparison of aggregate stability indices for soil classification and assessment of soil management practices
Summary In view of soil structure analysis and land-use and management history evaluation, several mechanical indices of soil structure were tested on 13 Italian soils. From the wet and dry sieving aggregate distributions, a pseudo-textural aggregation index (Ipta) and a mechanical aggregation index (Ima)) were determined and compared with other soil structure stability indices based on single-sieve analysis. The single-sieve indices S and WSI were good correlated with Ipta and Ima, showing the possibility of substituting the time-consuming aggregate-size distribution determinations. All the soil structure indices were correlated with selected semi-permanent soil characteristics. Soil struc…
Changes of humic substances characteristics from forested to cultivated soils in Ethiopia
The dynamics of the stable fractions of soil organic matter (SOM), the humic substances, has been rarely studied in tropical soils. We evaluated extraction yields, elemental composition, isotopic d 13 C abundance and solid-state 13 C NMR spectra of humic fractions isolated from five forested and cultivated soils in Ethiopia in order to assess the influence of deforestation and subsequent cultivation on the composition of humic fractions. In all locations, humic (HA) and fulvic (FA) acids, humin (HU) and a humic hydrophobic fraction extracted with an acetone–HCl solution (HE) were decreased as a result of deforestation and cultivation, but the magnitude of decrease was site-specific. While t…