Ted and Janice Blomgren raised organic vegetables. They conducted an experiment to compare the yield and cost effects of various mulches—black plastic, landscaping fabric, and straw—and of no-till versus conventional tillage. Treatments were as follows:
1. landscaping fabric left permanently in place; no-till
2. landscaping fabric removed annually to allow conventional tillage
3. black plastic mulch removed annually to allow conventional tillage
4. straw mulch left permanently in place; no-till
5. bare ground with conventional tillage (control)
The experiment was designed to run for three years. Yield data were collected for each plot. Time spent tending each was recorded, so that labor costs might be calculated and compared. Costs of mulching materials were also recorded for comparison.
Results from the first year: Bare ground with conventional tillage (#5) gave the highest yields of broccoli, cabbage, and beefsteak tomatoes. The permanent mulch of landscaping fabric (#1) gave the highest yields of cucumbers and eggplants. Labor cost was highest for the bare ground plots, where considerable time had to be spent hand-weeding. Total expenses were higher for the other plots, however, on account of the cost of the mulching materials. Landscaping fabric is good for about ten years. The cost shown below is one-tenth of the purchase price, to approximate one year’s cost. Black plastic mulch is good for only one year; the cost shown here does not include disposal. Straw also must be replaced every year:
—–Cost per 100’ bed—–
1: $7.70, $2.00, $9.70
2: 8.52, 2.00, 10.52
3: 8.34, 4.25, 12.59
4: 7.70, 20.00, 27.70
5: 8.98, 0, 8.98
Results from the second year: The experimental plan was modified slightly to drop treatment #4, straw mulch with no-till. This year bare ground with conventional tillage (#5) again gave the highest yield of beefsteak tomatoes, but black plastic with conventional tillage (#3) gave the highest yields of cucumbers, plum tomatoes, and watermelons. Landscaping fabric with conventional tillage (#2) gave the highest yield of cabbage.