Biodiversity is a fundamental component of nature. Just think about a forest in which many different animal and vegetable species coexist and in which every living organism is important because it keeps the system in balance. In nature, monotypes - entire areas containing a single species - do not exist, in the same way that the human race does not consist only of blonde people. When large areas of land are under intensive monoculture, significant imbalances occur over time.
Plants, like any living species, have their own nutritional preferences and therefore consume some elements more than others. The roots will release substances whose accumulation in the long run causes autotoxicity which in turn creates a phenomenon known as 'soil fatigue' or loss of fertility. In this environment, plant and animal pathogens typically associated with that crop will surely develop. When pesticides are applied, they attack not only the pathogens but also their inhibitors, and these substances often accumulate in the environment.
This is why it is essential to create, within monocultures, zones of biodiversity where indigenous flora and fauna can develop without human intervention and where nature can regain its balance and strength, with positive impacts on surrounding areas. When nature is healthy and resilient it enables whoever cultivates it to intervene minimally with targeted and non-invasive actions that can also strengthen the resistance of the plants themselves.