According to redpath and greg urban, what is the threshold amount for determing if a substantial basis adjusment is mandatory?

The quinoa seed is in high demand in wealthier countries such as the u. s. and japan. approximately 97% of all quinoa production comes from small farmers in bolivia and peru who farm at high elevations—8,000 feet or higher. the seed is considered highly nutritious. mostly grown and harvested in bolivia and peru, and sold to markets in other countries, the seed is now considered an important for these nations. the governments of bolivia and peru are hopeful that this product will increase the quality of life of their farmers.