Morphology, physico-chemical properties and classification of the soils developed on volcanic parent materials of Northern Province of Rwanda
Loading...
Date
2016
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
A study was carried out on soils developed from volcanic parent materials of Northern Province of Rwanda to expose the current soil conditions, aiming largely on pedological characterization but to a certain extent on assessment of potentials and limitations of soils for production of major crops in the area. Three representative pedons namely KNG-P1, KNG-P2and GHNG-P1were identified and described. Sixteen soil samples were collected from different pedogenic horizons and analysed in the laboratory for physico-chemical properties. Pedons were classified using USDA Soil Taxonomy and FAO-WRB for Soil Resources. Results showed that soils were shallow to very deep and well drained. Topsoils were very dark coloured with colour values of ≤ 2 in all pedons. Texture was generally loamy with bulk densities of < 1.35 g/cm3. Studied topsoils were medium acid (pH 5.57) to mildly alkaline (pH 7.41), with high to very high organic carbon ranging from 3.97 to 13.03%. pHNaF was > 9.5 in Pedons KNG-P1 and KNG-P2, reflecting exchange complex dominated by amorphous materials and/or humus complexes. Pedons KNG-P1 and KNG-P2 met the “andic properties” requirement of phosphorus retention capacity≥ 85%. Melanic index values indicated that these two pedons were characterised more by fulvic than humic acids. Nutrient imbalance was observed in studied soils, implying suboptimal nutrient uptake and toxicity. Degree of weathering of studied soils was low as indicated by weathering indices. Pedons KNG-P1 and KNG-P2 were classified as Andisols/Andosols and GHNG-P1 as Mollisols/Phaeozems. Land units represented by Pedons KNG-P1 and KNG-P2 were rated as marginally suitable while land unit represented by Pedon GHNG-P1 was rated as moderately suitable for the major crops of the area. Application of P fertilizers coupled with efficient placement and soil conservation should be undertaken in the study area.
Description
A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN SOIL SCIENCE AND LAND MANAGEMENT OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.
Keywords
Volcanic parent materials, Soil conditions, Pedological characterization, Northern Province, Rwanda