Organic fertilizers are safer than synthetic fertilizers.
First of all, both are fertilizers and has chemicals; both have their own advantages and disadvantages. Plants can't tell the difference between a naturally derived fertilizer and one that was produced synthetically in a lab. To a plant's roots, a nitrogen molecule is simply a nitrogen molecule. Organic fertilizers (manure, compost, bloodmeal, bone meal, etc.) do offer certain advantages over synthetically produced fertilizers. They release nutrients more slowly, which reduces the chance of over-fertilization. They also improve the overall structure of the soil (adding microorganisms, texture, air and water absorbing capacity) and in many cases, they can be obtained more cheaply than commercial fertilizers.There are also disadvantages to organic fertilizers. Because they release nutrients more slowly, they cannot always meet a plant's nutritional needs as immediately as a commercial fertilizer. It's also not always possible to know exactly how much or which nutrients you are applying (e.g. compost), because some types of organic fertilizers lack labels.