Comparison of four organic amendments with a chemical fertilizer applied to three vegetables in rotation

Field research, conducted for six seasons (1991-1996) on one soil type, com pared organic amendments (three formulations of fish bone meal (FBM) and a marine sediment enriched with fish, lobster, and crab meal) with an NPK che mical fertilizer (17-17-17) and a zero-N control (0-17-17). Each fertilizer material was applied preplant at 80 kg N ha(-1) to the same plot for six s easons that spanned two cycles of a three-crop rotation of seeded carrots, green beans, and transplanted cabbage. In plots receiving the organic amend ments, soil pH and Ca increased over time compared with those plots receivi ng 17-17-17. The increase of soil Mg was greatest in plots receiving the fo rtified marine sediment treatment. Soil and leaf K values were lowest with the FBM treatment, reflecting its low K composition (6-10-1). Soil and foli ar P values from the organic amendment plots were higher than those from th e 17-17-17 plots. Foliar N, Ca, Mg, Fe, and B were not consistently affecte d by 17-17-17 or the organic amendments, but foliar Mn was higher in crops receiving 17-17-17. Marketable yields of cabbage and carrots in plots recei ving the organic amendments were comparable with those from 17-17-17, but m arketable yields of green beans were consistently higher in plots receiving 17-17-17. Soil and foliar results indicate that the cumulative effect of r epeated application of these organic amendments is not detrimental to plant growth, and that these amendments produce marketable yields of cabbage and carrot equivalent to those of the chemical fertilizer.