Organic farming does not use synthetic chemicals (fertilizers, herbicides, fungicides, insecticides, pesticides in general). Crop protection is provided primarily in advance by selecting hardy and disease-resistant species, and then intervening as necessary with appropriate cultivation techniques. These techniques might include: crop rotation (not cultivating the same plant consecutively, thereby hindering the acclimated pests); using natural soil nutrient substances in a more rational and less intensive way; the planting of hedges and trees (which, in addition to re-creating the natural landscape, provide habitat for natural predators of pests and act as a physical barrier to possible external pollution); and intercropping (companion planting).
Fertilizers are “natural”, such as suitably composted manure that offers an irreplaceable richness of nutrients for the soil. Organic farming also uses other composted, organic substances (residues, etc.), and rock minerals. Another natural fertilizer is green manure, i.e. the incorporation of specially sown plants such as pulses or mustard. In conventional mega-industrial farms, the manure and plant residue are often considered wastes. They then become a huge problem requiring labor, machinery, and disposal on already scarce land.
If necessary for protection of crops, in organic agriculture it is acceptable to use natural plant substances, animals, or minerals, such as extracts from plants (pyrethrum derived from an herb); beneficial insects that prey on pests; and rock meal or minerals (such as copper and sulfur) to correct the structure and chemical characteristics of the soil.