Mapping of limestone deposits and determination of quality of locally available limestone in Rwanda
Journal of Soil Science and Environmental Management
Soil erosion, soil nutrient depletion and soil acidity associated to Aluminium (Al) toxicities are the main soil related constraints to agricultural development in many countries of sub-Sahara Africa. The lime plays an important role in improving soil acidity and hence favours plant nutrition. The aim of this study was to map out the available limestone deposits and to determine their selected quality. The selected quality of limestone (CaO, MgO and fineness factor) was analyzed using ethylene
... iamine tetraacetate (EDTA) method. The global positioning system (GPS) coordinates of limestone deposits were taken. The collected data were processed using Arc GIS 9. The fineness factor was determined by mechanically sieving the lime through a stag of 4 sieves of various aperture dimensions (2, 1, 0.5 and 0.2 mm). The map showed that the limestone deposits are scattered in Northern and Western provinces with more concentration in Northern region. Mpenge limestone had an average of 40% ±4.2 of CaO and 3% ±0.9 of MgO. However, its fineness factor of 63% ±2.01 found to be in good range. Gishyita deposit was heterogeneous in CaCO 3 , its CaO was 50% ± 20.02 indicating high variability within mines where CaO reached < 30%. Mashyuza deposit in Rusizi region had 50% ±3.4 of CaO and moderate MgO of 3% ±0.6. However, its fineness factor was 55.6% ±1.6 .The difference in lime quality observed in this study was possibly due to the origin of limestone rocks. However, the fineness factors were below the acceptable level because of non-additional grinding and lack of technological skills in producing lime. Therefore, this study recommends the use of grounded limestone after fine grinding.