Characterization of Selected Gypsites of Tanzania for Agricultural Use

This study was carried out to assess the suitability of gypsite as a soil amendment in the release of Ca and S. Besides the high potential of gypsite in improving crop yields in some countries, its use in Tanzanian agricultural soils is limited. This is attributed largely due to few types of research on their agricultural potentials. The gypsite samples used in this study were collected from Pindiro, Makanya, Itigi and Msagali sites. The X-ray fluorescence (XRF) method was employed to analyse the chemical compositions of the composite samples. The XRF results showed that the gypsites from the four sites varied in amounts of gypsum content from 35.76 to 82.36% for gypsite from Itigi and Pindiro, respectively. The contents of S were 15.32, 13.26, 10.52 and 6.65% for Pindiro, Msagali, Makanya and Itigi gypsites respectively. Calcium contents were 11, 9.5, 7.6 and 4.8% for Pindiro, Msagali, Makanya and Itigi gypsites, respectively. Analysis on extractable nutrients shows that when gypsite from Pindiro and Msagali that contained a high amount of S and Ca when applied in the soil, plants will be able to extract different nutrients for their metabolism at the same time improving soil physical properties. All the studied gypsite samples contain potentially toxic elements (Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn), but the levels are not potentially toxic to plants and hence do not interfere with plant nutrient uptake. Characterization of gypsite from other deposits in the country is required to generate information on their quality, quantity and suitability for use on soil amendment for increased agricultural productivity in Tanzania.