Growth and nitrogen recovery efficiency of potato (Solanum tuberosum) fertilised with shrimp shell pellets

摘要

In organic plant production, nitrogen (N) availability is often a growth-limiting factor. Under such conditions, off-farm waste-derived nutrient resources may be an alternative to meet the N demand. In this study, we described a production method for a shrimp shell (SS) pellet product and evaluated the N fertiliser effect and N recovery effciency (NRE) in a controlled climate pot experiment with potatoes. The experiment was set up with low, medium and high N levels of SS pellets in comparison with a standard mineral fertiliser (MF) at 9℃, 15℃ and 21℃. In a separate study, we examined the loss of N as N_2O from SS pellets in comparison with SS powder in a 100 days incubation experiment. The results documented the possibility to formulate a fertiliser pellet product from SS, and that SS pellets were an effective N fertiliser in potato at all growth temperatures. Nevertheless, a slightly slower development and lower tuber yields than for MF indicated a delayed N-availability from SS pellet fertiliser. NRE after use of MF was around 90, and about 70 for the different levels of SS pellets. The incubation experiment showed a higher rate of available N for SS powder than for pellets (67 and 39, respectively) after 100 days of incubation at constant humidity and temperature. This difference was attributed to a lower degree of dissolved materials and a higher rate of denitrification and N_2O emissions for pellets than for powder, probably caused by differences in physical properties, occurrence of anoxic hotspots and higher microbial activity around and inside the SS pellets.