Effects of Integrated Municipal Sewage Sludge with Chemical Fertilizer on Micronutrient Concentration in Soil and Radish (Raphanus sativus)

In order to study the effect of sewage sludge (SS) application individually and integrated with N-P-K fertilizer and application length on the amount of total and available micronutrient in soil and their concentration in root and shoot of radish (Raphanus sativus)، a 3-year experiment was conducted using randomized complete block design with two factors and three replications. The main plot included 6 fertilizer treatments consisting of control، chemical fertilizers، 20 ton. ha-1 of sewage sludge enriched with 50% chemical fertilizer، 20 ton. ha-1 of sewage sludge individually، 40 ton. ha-1 of sewage sludge enriched with 50% chemical fertilizer and 40 ton. ha-1 of sewage sludge individually. One-year، two-year، and three-year application of that fertilizer were considered as sub plots. The results showed that application of different treatments had significant effect on total and available micronutrient elements in soil and accumulation of these elements in root and shoot of radish. By increasing the application of these factors، micronutrient concentrations in soil and their uptake by plants were increased. Also، the effect of three-year application of organic and mineral fertilizers were better than one-year and two-year applications of these fertilizers on increasing the concentration of the micronutrient in soil and their uptake by plant organs. Interaction of the two factors had significant effect on available Zn content of soil، Fe and Mn concentration of radish root، and Cu of radish shoot. The results indicated that the highest increase in soil available Zn belonged to the continuous three-year application of 40 Mg. ha-1 sewage sludge. The highest uptake rate of Fe and Mn by radish root belonged to the continuous three-year application of 40 Mg. ha-1 + 50% sewage sludge. The highest Cu concentration in radish shoot belonged to the continuous three-year application of 20 Mg. ha-1 + 50% sewage sludge. Finally، regarding the result of this experiment and significant effect of application of sewage sludge individually or enriched with chemical fertilizer، it is suggested that sewage sludge enriched with chemical fertilizer and individually، may be applied، but care must be taken to avoid heavy metal entry into food chain and pollution of soils.