NS/S utilizes a two-pronged approach to conserving crop genetic resources from the southwestern US and northwestern Mexico. Ex situ approaches involve conserving samples of crop seeds under frozen storage conditions, where they may remain viable (able to germinate) for long periods of time. We also utilize in situ approaches that support and encourage the ongoing relationship between people and plants through which both natural and human selection pressures continue to result in the development of new crop varieties – the same relationship between people and plants that produced the diversity present today.
The NS/S Seed Bank is at the core of our conservation efforts. It serves as a repository for seeds, guarded in a safe environment for the proverbial "rainy day". In this case, the rainy day is when a crop can no longer be found growing in a farmer's field. Domesticated crops depend on an intimate relationship with humans - they don't exist in the wild. Over thousands of years, traditional agriculturists have selected and saved seed from plants that expressed a diversity of traits of interest to them or their communities - the ability to mature before the first frost, a sweeter taste, faster cooking time, or resistance to specific insects or diseases. Local, regional and global food security depends on this diversity. A seed bank's primary function is to conserve this genetic diversity for the future.