This national project has three major components: a searchable national database of crop responses to nutrients; updated soil test interpretations including critical soil test value; and a nutrient loss index tool. It will collate data from previous fertilizer field experiments into a large accessible database. These data will be used to develop soil test, crop yield response curves for particular crop/soil/regional situations. Advisors will be able to access and interrogate these data on-line and use specific data to develop critical soil test values. Around 4000 experiments will be entered into the database.