Fertilizers add elements to the soil essential for plant growth. Pesticides work to kill pests and bugs that can harm the plants. For either fertilizers or pesticides, organic and chemical options are available. Following organic farming practices, organic fertilizers and pesticides use substances composed from living, natural things. Chemical fertilizers and pesticides use synthetic ingredients to do their work. While chemical fertilizers and pesticides can create larger plants and crops, their drawbacks make plants more susceptible to disease and pests, and can pose a risk to humans.

Advantages of Chemicals
Chemical fertilizers are refined to extract nutrients and bind them in specific ratios with chemical fillers. These could include petroleum, rocks or possibly organic material. While some of the chemicals may be naturally occurring, the nutrients are refined to their pure state, stripped of organics that control breakdown.
Chemical fertilizers and pesticides provide immediate improvement, often within days. Keenly analyzed, they produce the exact ratio of nutrients (in the case of fertilizer) or poison (if a pesticide) that is required. Most are fairly inexpensive compared to most methods of organic farming.

Disadvantages of Chemicals
Many chemical fertilizers are made from nonrenewable resources such as fossil fuels. While they provide more growth to the plants, they don't add nutrients to the soil. Trace elements are not replaced to the soil, resulting in depletion over the long term. Repeated applications of chemical fertilizer can result in a toxic buildup in arsenic, cadmium and uranium in the soil and even the fruits and vegetables.
Chemical pesticides can run off into ground water, poisoning water supplies. They can also leak into vegetables and fruits. Chemical pesticides also kill earthworm populations, damaging the quality of the soil.

Advantages of Organics
Organic fertilizers include animal manures, compost, bone meal and blood meal. They tend to be less refined, so there's little to no chemical processing required. The natural environment can more easily break them down and absorb them. Organic fertilizer contains micro-organisms that help plants convert nutrients to food. The organic matter also helps to break down old plant material to return the nutrients to the soil.
Organic pesticides includes natural substances such as cedar or grasses that have natural fungi that resists insects. Others may contain boric acid or diatomaceous earth, both natural but effective products. They are less poisonous to the environment and generally pose less harm to people.

Disadvantages of Organics
Organic fertilizers are not immediately available to plants. Before they can be used in organic farming, plants must first break down the micro-organisms into simpler molecules and ions. Fertilizers such as animal manure can cause many problems if used improperly and can leak into water supplies. Farmers can only guess at the amount of nutrients provided by organic fertilizer, while chemical alternatives are more exact.
While most organic pesticides are safer than their chemical counterparts, some do have risks. Pyrethins, derived from flowers, have been linked to autism in some studies, according to the Sierra Club.

Warnings
Even organic fertilizers and pesticides can be unsafe if used improperly. Always follow any warnings or directions included on the product label. Remember that "environmentally safe" is a relative marketing term that doesn't have an industry definition. Follow caution and common sense.

From Network Resources