Organic soil amendments can provide key micro and macro nutrients to both perennial and annual crops that are to be certified as organically grown. The various amendments, which include blood meal, fishmeal, dehydrated manures and others, vary widely in their nutrient content as well as in the availability of those nutrients. A series of field trials were established over a period of four years to monitor soil nitrogen availability following applications of several different soil amendments approved for organic production when each was applied to supply 80 kg ha-1 of N. Each crop trial was replicated over two field seasons. Crops were chosen to test fall, spring and summer-seeded crops and included winter wheat, spring broccoli and summer sweet corn. Soil available N as ammonium or nitrate was measured regularly during the growing season of each crop. In each of the three crops, the fish meal treatment was consistently superior to the other organic amendments in both crop yield and crop nutrient content.