ASSESMENT OF SOIL FERTILITY STATUS OF SELECTED RICE GROWING AREAS IN KILOMBERO DISTRICT - MOROGORO, TANZANIA

Soil fertility is an important factor in enhancing crop productivity. The study is aimed at assessing the soil fertility status in selected rice growing areas in Kilombero district and understand fertility variability among soils selected. Composite soil samples were collected in these rice growing areas at 0–20 cm deep and characterized for soil fertility status. This was done by analyzing twenty soil samples from rice growing villages of Kilombero district, whereby 20 soil samples were taken from 20 rice growing villages. The soil analysis included determination of total N, OC, P, soil pH, textural classes, exchangeable bases and micronutrients (ZN, Cu, Mn and Fe). The results showed that the soils surveyed are slightly to moderately acidic (pH 5.2 to 6.2). Results indicated that 80% of the soils were sand, 15% clay and the remaining 5% had loamy textural classes. Organic carbon ranged from very low to medium (0.40-2.53%), total N (0.11-0.32%). Also, results indicated that 50% of soils had P deficiency and 100% had inadequate S levels. In addition, 90% of the soils had inadequate exchangeable K and exchangeable Mg levels ranged from very low to medium (0.10-2.24 cmol(+) kg-1 ). Soils indicate to had 95% very low Exchangeable Ca with low base saturation. The CEC ranged from low to medium (7.0-21.60 cmol(+) kg-1). Extractable micronutrients such as Fe and Mn were adequate but Zn and Cu were inadequate in 35% and 10% of the soils, respectively. Results indicated that N, P, K, Ca and Zn were generally the limiting nutrients of which S and Na were limiting in all selected soil. Generally, the categorization of nutrient status indicated poor fertility in the studied soils. The results of the study area show deficient levels, however, there were variations in nutrient deficiencies in selected soils