he use of plastic mulches is common in herb and vegetable production. Plastic mulches control weeds within the crop row and modify the crop microenvironment. They form a physical barrier for weed seedlings, prevent sunlight from reaching the soil surface, and modify the microenvironment affecting weed seed germination and subsequent weed populations.
Plastic mulches also can increase vegetable crop growth, improve earliness and yield compared to bare-ground production systems. The effect of plastic mulch on weed and crop microenvironment (e.g., soil temperatures, mulch surface temperatures, and radiation balance) is determined primarily by optical properties of the material, extent of mulch-soil contact, and prevention of evaporation from the soil surface.
Black plastic is preferred for early season production of warm season crops such as tomato and basil because of its warming effect on the soil. But later in the season black plastic mulch can reduce yields because of excessive surface and soil temperatures. The apparent surface temperatures of black plastic mulches can approach 158.0 to 176.0 degrees F (70 to 8) degrees C) during midday.
Mulches with lighter surface colors, such as red and blue, have been developed to slow the accumulation of heat units and improve later season crop growth compared to black plastic mulch. Tomatoes in red mulches set fruit earlier, produced more ripe fruit, and had a greater number of fruit than plants grown in black plastic. The effectiveness of the red mulch is attributed primarily to the far-red to red photon ratio reflected to the developing fruit and nearby leaves from the mulch surface.
Problems still exist with plastic mulches. The petroleum used to synthesize agricultural mulches is a non-renewable resource. Removing plastics from fields for disposal is a labor-intensive and unpleasant job.
A foam mulch system was developed that can be applied as an aqueous mixture of cotton and cellulose fibers, gums, starches, surfactants, and saponins that dries to a one-inch-thick mat. This mulch may overcome the difficulty in applying and lack of persistence with natural mulches.
Foam mulch also has the advantage of being able to be incorporated into the soil without requiring disposal like some plastic mulches.
The objective of this study was to determine the effect of foam mulch and its color on weed control within the crop row and on yields of basil (Ocimum basilicum) and tomatoes (Lycopersicon esculentum).
The foam mulch maintained its integrity for the entire growing season and provided weed control within the crop row comparable to black plastic mulch. The only weeds that emerged in the crop row were through holes in either the black or foam mulch. Foam mulch color did not affect weed control because regardless of color it did not allow light penetration, and served as a physical barrier impeding weed emergence.
Basil shoot biomass was not affected by mulch treatment. Mulch color affected early, ripe fruit, and total yield of tomato. Tomato yields in the blue foam were greater than in other treatments.
Yields in the black foam mulch were similar to those in black plastic mulch.
Further research is needed to characterize the effects of foam mulch on crop microenvironment. Currently foam mulch is being commercialized for use in the home landscape and other high-value situations.
