Nitrogen Mineralization of Grass Clippings — A Case Study in Fall Cabbage Production

In this three-year field study, grass clippings were applied to fall cabbage to determine the effectiveness of using this common yard waste as a nutrient supplement for crops. Objectives of this research were: 1) To determine the characteristics of grass clippings used in this study; 2) To monitor soil 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 rates. The grass clippings used were heterogeneous in their chemical and physical characteristics. Even at the same application rate, soil NH₄-N and NO₃-N concentrations and yields were very different for each year. To avoid over- and underfertilization, targeted N supply from grass clippings should be less than necessary to grow fall cabbage. Additional N fertilizer can be applied based on the PSNT (pre-sidedress soil nitrate test).