2013 ASHS Annual Conference

Three organic mulch alternatives for organic tomato production (cv. WV63) were compared to a bare soil control. A complete randomized design of sixteen plots measuring 2.4 by 2.4 meters was established and each treatment was replicated four times for a total of twelve treatment plots and an additional four control plots. Treatments included an organic waste wool application to a depth of 5 cm, organic cocoa hulls also applied to a depth of 5 cm, and white clover living mulch. Control plots were left bare. Data were collected on surface and soil temperatures, yield (weight and number of fruit), growth characteristics (leaf area, height, and width), and weed suppression.  Significant differences in yield were observed. The highest overall yield was observed in the cocoa hull plots followed by plots mulched with wool and the control plots. Plots with white clover living mulch yielded significantly lower than all treatments and the control. Extrapolated seasonal yields were 306, 279, 201, and 64 metric tons per hectare for cocoa, wool, control, and living mulch, respectively. Yield during the first two harvests was significantly higher for wool than other treatments or the control. In addition the average weight of 147 grams of harvested tomatoes in the wool treatment was significantly higher than the 129 grams per fruit in the control and 132 grams per fruit in the cocoa plots. No significant differences were observed in plant height or leaf area. Average peak surface temperatures were 53 °C, 48 °C, 43 °C, and 33 °C, for cocoa hulls, wool, control, and living mulch respectively. All treatments lowered subsurface temperature when compared to the control and ranged from 21.6 °C in the control plots to 20.7 °C in the living mulch plots. Weed suppression as measured by time to remove weeds was greatest in cocoa hull plots, followed by the clover, wool, and control treatments. Overall the cocoa hull treatment performed best in total yield and weed suppression. However, if cost, earliness, and/or fruit size are factored wool can be considered a viable alternative to cocoa hulls in organic tomato production.