Effect of wastewater re-using as nutrient and irrigation source to improve crop productivity in Morogoro

A study was carried out to determine the effects of re-using wastewater effluents as main source of plant nutrients and water for irrigation to improve crop productivity. The study was conducted at Mafisa ward in Morogoro urban using 60 pots measuring 10L. Three crops namely paddy, swisschard and tomatoes were grown and irrigated using both tap water (as control) and wastewater drawn from waste stabilization pond number 2. Five treatments of 0%, 25%, 50%, 75% and 100% wastewater were tested in a Completely Randomized Block Design (CRBD) with 4 replications. Half of the treatments received NPK at the rate of 10 mg per plant. For paddy observations were made on the number of tillers and panicles, plant height, weight and number of grains. Based on tillers it was found that wastewater only irrigated pots yielded 26 stems on average whereas NPK added wastewater produced a mean of 30 tillers per pot. For swisschard, observations were made on leaf numbers, weight of fresh leaves, and leaf surface area. The wastewater only irrigated plants yielded an average of 22 leaves per pot whereas NPK added wastewater yielded an average of 25 leaves per pot. Heavy rains destroyed all tomatoes at flowering stage that it was not possible to determine productivity. Results for heavy metal contents in the treated wastewater used in the study indicated that the wastewater contains low mean quantities of Pb (0.01µg/l), Cr (0.14µg/L), Cu 0.42µg/L) and Zn (59.4µg/L) compared to the recommended international levels of Pb (10µg/l), Cr (150µg/L), Cu(2000µg/L) and Zn (3000µg/L). Thus wastewater proves to be safe for agriculture production.