Assessment Of Nitrate Levels In Water And Soils For Agriculture And Human Utilization In Singida District, Tanzania

ABSTRACT

Population growth in urban areas has caused increase in demand of good quality water for domestic use. Due tohigh nitrate levels in water sources reported by District water authoritiesin Singida District, this study was carried to determine sources, levels and distribution of nitrates in water and soils for agriculture and human utilization. Firstly, a reconnaissance survey was carried to identify water sources with high, medium and low levels of nitrates and determine nitrate levels in surrounding soils. Surface water, underground water and surrounding surface soils samples were randomly collected and analysed for nitrate levels.Their results assisted in identifying areas with high, medium and low nitrate levels where detailed soil sampling and analyses for nitrate levels in soils was carried out.Analysis of soils and water resources revealed high levels of nitrates in water samples ranging from 105 to 476mgL-1 and25.2 to 114.8mgkg -1 in soils.The distribution of soil nitrates along transects indicated that higher levels were recorded at lower slopes whilelower levels were recorded in the upper slopes. The distribution of nitrate with soil depth was quite variable. In some areas the soil nitrate levels increased with increasing soil depth while in other areas nitrate levels decreased with increasing depths.The nitrate levels in water found to beabove the tolerable limits of 20 mgL-1 and 50 mgL-1 set by TBS (2005) and WHO (2007),respectively. Nitratelevels in soils are within the tolerable limits forcrop production. Due to observed high nitrate levels in water, more researchis required to generate sufficient data on the suitability of water for human consumption. The study on the dynamics ofnitrate in soils and water is recommended in orderto come up with strategies of reducing nitrate levels in water.