Abstract: (14573 Views)
Sewage sludge (SS) as a source of macro- and micro nutrients has been utilized in many countries for crop and
vegetable production. To compare the influence of SS with chemical fertilizer on macro- and micro nutrients
bioavailability in three textural classes of a calcareous soil after harvesting spinach (Spinacia oleracea L.), a factorial
experiment was carried out in a completely randomized design with two factors and three replications under glasshouse
conditions. The first factor was SS levels (0, 10, 20, 40, and 80 mg per kg soil) and the second factor was soil textural
classes (sandy, sandy loam, and clay loam). A chemical fertilizer treatment was used for comparison with the applied
SS treatments. Results indicated that total nitrogen (N) and available phosphorus (P) was significantly higher in SS
amended soils compared to fertilizer treatment. Effect of increasing soil potassium (K) due to addition of SS was less
than P and N, which is probably due to low content of K in SS. Soil DTPA extractable iron, zinc, copper, and
manganese were significantly increased in SS treatments in all soil textures and were higher than fertilizer treatment.
Based on nutrients’ bioavailability in soil after harvesting spinach, especially at high rates of SS, addition of most
nutrients is not necessary for the next crop. Concentration of DTPA extractable cadmium (Cd) and lead (Pb) was not
detectable in all treatments. Therefore, because of low contents of Cd and Pb in the utilized SS, reaching to a toxic level
of these elements in soil is unexpected. However, if high levels of SS are applied frequently, soil test is recommended
for monitoring heavy metals concentration in amended soils. Prior to any SS recommendation, the results of this
research need to be verified under field conditions.
Type of Study:
Research |
Received: 2012/11/23 | Accepted: 2017/02/14 | Published: 2017/02/14