Monoculture or monocropping is the agricultural practice of growing a single crop year after year on the same land, in the absence of rotation through other crops or growing multiple crops on the same land, which is known as polyculture. Polyculture is much healthier for the soil as it feeds the huge diversity of insects, bugs and microbes that are responsible for keeping the soil healthy. Plant diversity can also work as a natural pesticide. Think of it like your stomach - it works much more effectively when there is a multitude of balanced good bacteria working together. Monocropping strips this away.
While growing one type of crop has no doubt simplified farming practices and aided our ability to increase yields to feed our growing population, there are also a number of drawbacks. Removing multiple plant species in favour of a single crop eventually depletes the soil of its biodiversity and also increases the amount of opportunistic pests that feed on the crops. As the soil becomes exhausted of its nutrients, the need for more chemical inputs to ensure crop growth can take place as well as removal of pests increases. As we know, these synthetic fertilisers and pesticides negatively affect the soil even more which has consequences for our environment and quality of food. Poor soil health will lead to food that is less nutrient dense and affect the ability of the soil to draw down and store carbon from the atmosphere. Meaning that the soil's ability to help reverse climate change is negatively affected.
Not all monoculture is bad and there is a place for it in farming if done correctly. However, mass scale monoculture that is common in soy, wheat, corn, avocado, palm and banana production that extends for miles and miles is an issue and will affect arable top soil over time. Another alarming element to mass scale monoculture is that a large amount of the corn, soy, and wheat grown in monocropping is then fed to animals in intensive farming practices. Some say even up to 40% of grain production goes to grain fed animals. This is a great reason to avoid grain fed meats if you are environmentally conscious.
According scientists, at current rates of soil destruction (through decarbonisation, erosion, intensive farming, desertification, chemical pollution), within 50 years we will not only suffer serious damage to public health due to a qualitatively degraded food supply from diminished nutrition and loss of important trace minerals, but we will literally no longer have enough arable topsoil to feed ourselves. Without protecting and regenerating the soil on our 4 billion acres of cultivated farmland, 8 billion acres of pastureland, and 10 billion acres of forest land, it will be impossible to feed the world, keep global warming below 2 degrees Celsius, or halt the loss of biodiversity.