Quality investigation of organic fertilizers,inorganic-organic compound fertilizers and compound fertilizers in Zhejiang province

An investigation was carried out on the physical and nutritional quality of fertilizers in Zhejiang province.Analysis results of 61 samples collected from domestic compound fertilizers,organic-inorganic compound fertilizers and organic fertilizers showed that majority of the samples met the relevant standards listing criteria.For the criteria for nutrient of these fertilizers was 95.0% for organic fertilizers,72.2% for organic-inorganic compound fertilizers,and 86.3% compound organic fertilizers.Heavy metals were also tested.The results showed that Cu,Zn,Pb,Cr and Cd contents were highest in organic fertilizers followed by organic-inorganic compound fertilizers.Cd and Pb contents of organic fertilizer samples was 35% and 10% higher than the upper limitation of national standard respectively,while Pb,Cd and Cr in all organic-inorganic compound fertilizers samples measured under the national standard.The contents of heavy metals in commercial organic fertilizers were significantly correlated with that in the raw organic materials.