The 2012 ASHS Annual Conference

This study evaluated the effects of pre-plant compost incorporation and subsequent fertigation during the growing season on organic production of zinnia (Benary’s Giant Mix) cut flowers in a high tunnel. There were three pre-plant compost applications: composted broiler litter, vermicompost, and control (no compost). The compost rate used was 6 tons/acre and the compost was incorporated into the bed before laying the plastic mulch. Under each compost treatment, there were three fertigation treatments: no fertilizer, organic low [100 ppm nitrogen (N) from MultiBloom, a liquid catfish processing byproduct], and organic high (200 ppm N from MultiBloom). Each treatment combination included 16 zinnia plants which were planted half ft apart. Each treatment combination was replicated 3 times. Plants were transplanted into the beds in early September and each plant was supplied with 200 mL of solution from each fertigation treatment once a week. Zinnia stems were harvested as soon as the blooms were completely opened, starting from early October through November. Results indicated that during early stage of plant growth, plants that received compost had significantly higher SPAD reading than plants did not receive any compost, and plants that received composted broiler litter had significantly higher SPAD reading than plants that received vermicompost. Plants that received composted broiler litter had significantly higher plant growth index than plants that received no compost. However, plants that received vermicompost had similar plant growth index as plants received no compost. Results also indicated that both pre-plant compost incorporation and fertigation during the growing season increased the total number of stems produced.