Organic farming is an agricultural strategy that emphasises crop rotation and companion planting while utilising organic fertilisers such as compost manure, green manure, and bone meal. It began in the early twentieth century as a reaction to rapidly changing agricultural techniques. Globally, certified organic agriculture covers 70 million hectares, with Australia accounting for more than half of that total. Various organisations are still working to improve organic farming today. Biological pest control, mixed cropping, and insect predator breeding are all encouraged. Organic guidelines are intended to allow the use of naturally occurring compounds while forbidding or severely restricting the use of synthetics. Natural insecticides like pyrethrin and rotenone, for example, are permissible, whereas synthetic fertilisers and pesticides are often prohibited. Copper sulphate, elemental sulphur, and Ivermectin are examples of synthetic chemicals that are permitted. GMOs, nanomaterials, human sewage sludge, plant growth regulators, hormones, and antibiotics are all examples of genetically modified organisms.