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

Abstract

Field research, conducted for six seasons (1991–1996) on one soil type, compared organic amendments (three formulations of fish bone meal (FBM) and a marine sediment enriched with fish, lobster, and crab meal) with an NPK chemical fertilizer (17–17–17) and a zero-N control (0–17–17). Each fertilizer material was applied pre-plant at 80 kg N ha−1 to the same plot for six seasons that spanned two cycles of a three-crop rotation of seeded carrots, green beans, and transplanted cabbage. In plots receiving the organic amendments, soil pH and Ca increased over time compared with those plots receiving 17–17–17. The increase of soil Mg was greatest in plots receiving the fortified marine sediment treatment. Soil and leaf K values were lowest with the FBM treatment, reflecting its low K composition (6–10–1). Soil and foliar P values from the organic amendment plots were higher than those from the 17–17–17 plots. Foliar N, Ca, Mg, Fe, and B were not consistently affected 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 receiving the organic amendments were comparable with those from 17–17–17, but marketable yields of green beans were consistently higher in plots receiving 17–17–17. Soil and foliar results indicate that the cumulative effect of repeated 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. Key words: Fish bone meal, marine sediment, organic amendments, vegetables