Organic Mulch as an Alternative to Black Plastic Mulch

Organic vegetable growers use plastic mulch to conserve water and control annual weeds. However, black plastic mulch costs producers $250-300 per acre and generates 100-120 lb/acre of un-recycleable petroleum-based waste that goes to landfills each year. By comparison, municipal leaf mulch is readily available in many municipalities and can be relatively inexpensive, and sometimes free to growers. In this study, we are assessing the effect of three mulch types: black plastic mulch, leaf mulch, leaf +straw mulch on tomato marketable yield, number of marketable fruits, and soil nutrients. Soil nutrients were assessed at the beginning and end of the season. Leaf mulch has 11 lignin, 4.7% hemicellulose and 30.4% cellulose. Carbon to nitrogen ratio is 20.7. Weeds were suppressed in leaf and leaf+straw for the first 8 weeks similarly to black plastic. Tomato ‘Black Cherry’ marketable yield is accumulation of five harvests. Tomato plants in leaf +Straw were the highest yielding plants throughout the season reaching 16.8 tons/ha followed by leaf mulch and plastic mulch each at 12.0 tons /ha. Tomato fruit number averaged 111 per plant in either leaf or leaf+straw whereas 95 tomato fruits/plant in plastic mulch. The organic mulch of leaf + straw can be considered a viable alternative to black plastic mulch to grow organic specialty tomato crop successfully.