The effects of repeated application of two composts differing in carbon / nitrogen (C/N) ratio on weekly soil nitrate nitrogen (NO3-N), weekly soil ammonium nitrogen (NH4-N), and leaf lettuce yield are being studied in trials near San Luis Obispo. One compost type (HiCN) is prepared primarily from yard wastes and has a C/N ratio of 29 - 32:1 The other compost (LoCN) is a compost prepared primarily from feedlot manures and has a C/N ratio of 10 -12:1. Prior to transplanting leaf lettuce, both composts are being applied and incorporated in the same plots repeatedly over four crop cycles at rates of 9, 18, 36, and 54 Mg ha-1 (dry mass) in each application. No other fertilizer is applied.
Education Summary: A meeting is being planned for September 1996 in Arroyo Grande (San Luis Obispo Co) on Compost and Mulch Utilization in Agriculture. The meeting is directed toward row crop and orchard growers, landscapers, and waste management professionals. Speakers include UC Specialists and Farm Advisors and a panel of growers.