Nutrient Element Contents and Cation Exchange Capacity in Fine Fractions of Southeastern Nigerian Soils in Relation to Their Stability
Titel:
Nutrient Element Contents and Cation Exchange Capacity in Fine Fractions of Southeastern Nigerian Soils in Relation to Their Stability
Auteur:
Igwe, Charles A. Nkemakosi, Juliet T.
Verschenen in:
Communications in soil science and plant analysis
Paginering:
Jaargang 38 (2007) nr. 9-10 pagina's 1221-1242
Jaar:
2007-05
Inhoud:
Soils collected from 15 locations from SE Nigeria at the 0- to 20-cm depth were studied for the nutrient elements of fine fractions and their role in the stability of the soils. The objective was to understand the role of these elements in the stability of the aggregates. The fine fractions were clay and silt, and elements measured in the fine fractions were exchangeable sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), exchangeable acidity (EA), cation exchange capacity (CEC), and available phosphorus (P). The aggregate stability was measured at the microlevel with clay dispersible indices and water-stable aggregate (WSA) <0.25 mm, and at macrolevel with other WSA indices and mean-weight diameter (MWD). Soils varied from loamy sand to sandy clay. There were more exchangeable cations, CEC, EA, and available P in clay than in the silt fraction. Whereas EA values ranged from 2.8 to 10.4 cmol kg-1, they were between 1.6 and 9.2 cmol kg-1 in silt. The CEC in the clay fraction was from 7.4 to 70 cmol kg-1 and between 4.0 and 32.8 cmol kg-1 in the silt fraction. The WDC were from 50 to 310 g kg-1 while the average dispersion ratio (DR) was generally higher than the corresponding clay-dispersion ratio (CDR), and the MWD ranged from 0.45 to 2.68 mm. Soils with WSA skewed mostly to higher WSA (>2-1.00 mm) had a higher MWD. Exchangeable Ca2+ in clay correlated significantly with CDR and WSA sizes 1.0-0.5 mm and 0.5-0.25 mm (r=0.45,* 0.51,* and 0.60*), respectively, but negatively correlated with clay flocculation index (CFI) (r=-0.45*). Also, available P in clay correlated respectively with CDR and CFI (r=0.45*, -0.45*), whereas K+ in silt correlated significantly with WDSi (r=0.64*), CFI (r=0.62*), and CDR (r=-0.65*). Principal component analysis revealed that elemental contents in the silt fraction can play very significant roles in the microaggregate stability.
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