Agriculture creates a conflict over the use of land between wildlife and humans. Land use for agriculture has been a driving force in creating biodiversity loss. The increase in the amount of pasture and crop land over the last few hundred years has led to the rapid loss of natural habitats. The Food and Agriculture Organization of the United Nations estimates that more than 40% of earth’s land surface is currently used for agriculture. Because so much land has been converted to agriculture, habitat loss is recognized as the driving force in biodiversity loss. A decline in farmland biodiversity can be traced to changes in farming practices and increased agricultural intensity. Nonetheless, according to the FAO, "biodiversity is just as important on farms and in fields as it is in deepriver valleys or mountain cloud forests". The world has acknowledged the value of biodiversity in treaties in recent years, such as in the 1992 Convention on Biological Diversity. Species face habitat fragmentation which can create a genetic bottleneck. Monoculture, the practice of producing a single crop on a given piece of land, including crop rotation, produces optimum yields, but has implications for the biodiversity of farms. Heterogeneity, the diversity of the landscape, has been shown to be associated with species diversity. Butterfly abundance has been found to increase with heterogeneity, for example. Land that is not cropped, such as fallow land, grass margins in the spaces between different fields, and strips of scrub along field boundaries increases heterogeneity, and thus the biodiversity of a farm. The plants attract insects, will which attract certain species of birds, and those birds will attract their natural predators. The cover provided by the uncropped land allows the species to move across the landscape. In Asian rice, one study showed crop diversification by growing flowering crops in strips beside rice fields could reduce pests so that insecticide spraying was reduced by 70%, yields increase by 5%, together resulting in an economic advantage of 7.5% .
