Nitrogen mineralization of grass clippings - Case study in fall cabbage production

In this three-year field study, grass clippings were applied to fall cabbag e to determine the effectiveness of using this common yard waste as a nutri ent supplement for crops. Objectives of this research were: 1) To determine the characteristics of grass clippings used in this study; 2) To monitor s oil NH4-N and NO3-N dynamics in the upper 30-cm soil layer over time; and 3 ) To determine fall cabbage yield at various grass clippings application ra tes. The grass clippings used were heterogeneous in their chemical and phys ical characteristics. Even at the same application rate, soil NH4-N and NO3 -N concentrations and yields were very different for each year. To avoid ov er- and underfertilization, targeted N supply from grass clippings should b e less than necessary to grow fall cabbage. Additional N fertilizer can be applied based on the PSNT (pre-sidedress soil nitrate test).