When you apply Non-Organic fertilizer, not only are you using synthetic forms of nitrogen(the element that provides the green color), but these Non-Organic forms of fertilizer are quick release therefore they don’t last as long. When you apply Non-Organic fertilizer, it only feeds the grass plant, not the soil, therefore it infiltrates the soil profile MUCH quicker than Organic fertilizer, therefore the lawn needs to be fertilized much more often as it will start to lose its dark green pigment. Organic fertilizer is slow-released. Its components are all derived from natural, organic material including feather meal, poultry meal, bone meal, etc. It feeds the soil. Over time, the soil releases the nutrients slowly, lasting much longer and providing a much longer lasting green pigment.