Effects of chemical and organic fetilizers on yield and nitrate accumulation in spinach (Spinacia oleracea L.)

In order to study the effect of conventional and organic fertilizers on growth, yield and nitrate accumulation of spinach, a greenhouse experiment was carried out in factorial based on randomized completely design with three replications in a commercial greenhouse located at Lahijan. Treatments were three levels of municipal soil waste compost (0, 50 and 100 t ha-1), five chemical fertilizers levels (0, 1/3, 1/2, 2/3 and complete content of recommended chemical fertilizer (N.P2O5.K2O) for spinach) and combination of different levels of chemical fertilizers and municipal solid waste compost. Result showed that by increasing chemical fertilizers and municipal solid waste compost. quantitative characteristics (wet and dry weigh, height, leaf area, and yield) increased. Also, integrated of compost with chemical fertilizers (specially 100 t∙ha-1 compost+chemical fertilizers) compare to only apiece application of fertilizers, had more affected to spinach yield. The lowest nitrate content was observed in compost application that no significant differences have with control. Result show that application 50 t/ha compost can be substitute 45.83% and application 100t/ha compost can be substitute 73.27% using current recommendation of chemical fertilizers for spinach and low content nitrate accumulation in plant.