Staked vs Unstaked
Colored Plastic Mulch
Student : David Agle
Project Advisor: Dr. Mark Bennett
Academic Advisor: Dr. Jim Metzger
In today's vegetable industry, farmers face the constant challenge of maximizing yields from high quality land. The industry has seen many improvements over the last twenty-five years in irrigation, genetics, and pest control. Some crop production has also changed from bare ground to plastic mulches, which aids in weed reduction, water conservation, and elevated soil temperature (Lamont, 1993). These plastic mulches may have much more to offer than just these three advantages however.
In 1985, Michael J. Kasperbauer and Patrick G. Hunt stationed at the USDA-ARS Soil and Water Conservation research lab in Florence, SC, painted black plastic mulch red, yellow, orange, and green to observe effects on vegetable crop growth. The two also worked in cooperation with Dennis R. Decoteau from Clemson University testing several different vegetable crops grown on the various colors of mulches. Tomato (Lycopersicon esculentum) production on red plastic mulch showed a 20% increase in number one fruit compared to the present industry standard, black plastic mulch (Orzolek, 1998a).
The increase in crop yield has been traced to the color sensitive pigment system in plants called phytochrome. Phytochromes absorb both red (R) and far-red (FR) (just beyond the visible spectrum) light. The more far red light (or greater the FR/R ratio) usually resulted in more aboveground growth. Far red light reflected to the shoots and developing fruit of tomato plants acts through the plant's phytochrome system to direct more new growth to be aboveground. Much of the aboveground growth is directed toward the developing fruit which leads to economic gain for the grower in more fruit production (Naegely, 1998).
Another advantage of growing tomatoes on red mulch is reduction in the number of root knot nematodes. Because the plants produce less root growth, and the fruit matures earlier, the plants seem to outgrow root knot nematodes. Root knot nematodes drain energy from the plant, especially when the nematodes are laying eggs. Under black plastic, the nematodes are usually laying their eggs the same time fruit production is beginning, but the plants above red plastic have a little bit of head start, and have usually begun fruit production before the nematodes drain much energy (Naegely, 1998).
Tomato production on silver plastic mulch also produced a significant increase in marketable fruit (Orzolek, 1998b). This may not only be due to the increased light reflected, but the reflective temperatures (heat reflected from the mulch to the plants canopy) as well. Reflective air temperatures above 13 different colored mulches were measured in 1994 at the Penn State University Horticulture farm. The highest temperature was recorded above co-extruded silver SLT (silver on one side, and black on the other). It was 18° F warmer above the SLT than above the black on June 16. The air temperature was 68° F and the reflective air temperature above bare ground was 108° F, 7° F cooler than above the black plastic. Generally, plastics with higher reflective temperatures will produce higher yields for warm season crops. (Orzolek, 1998a).
Technology in the plastic industry now allows colors to be added during the manufacturing process. Instead of having painted mulches, a much more consistent colored plastic product is being produced not only in black, brown, and clear, but wavelength selective green (IRT), blue, yellow, orange, co-extruded (one color on one side, and another on the other side), and red. The red product has been the toughest to produce since the amount of dye incorporated into the polyethylene determines the amount and type of red light reflected. Now that the manufacturing process and product uniformity has improved, use of colored mulches at the commercial vegetable farm level approaches feasibility (Orzolek 1998a ).
Problem Identification and Justification
The problem being studied will be the affects of red and co-extruded silver mulch on commercial tomato production as compared to the current industry standard of black plastic. While much research has already been done in this area, the need for a trial at a true commercial vegetable facility remains. As with any new technology, someone needs to be the grower that implements the new technology on a large scale. Running a trial in an area with substantial vegetable cultivation (the Eden NY site) will introduce this new technology and allow the first hand observations that many farmers feel is required before adopting this new practice.
Perhaps the greatest justification for this trial is the comparison between staked and unstaked tomatoes. Little research has been done to evaluate if there is a significant increase in yield for unstaked tomato production. If the affects of the reflected light on fruit set take place before much leaf and vine cover occur, colored mulches will likely be successful for bare ground production. If the yield increase occurs only for the staked plots, it can be assumed that unstaked production will continue with the current black plastic. Furthermore, now that the cost of colored plastic mulches has dropped, and the quality of plastic produced has improved, use of colored mulches approaches feasibility. If the gain in yield outweighs the additional cost, colored mulches could become common place in vegetable production.
The objective of this experiment is:
¨ To compare fruit production from each color of plastic based on:
4. total fruit weight
5. ripening date
¨ To compare plants grown on each color of plastic based on:
1. nutrients present from tissue samples
2. total dry weight
¨ To compare unstaked production to staked production for each color plastic based on above criteria
¨ To provide information on colored mulches to:
1. Vegetable producers
2. Extension and research personnel
¨ To determine the cost effectiveness of colored mulches
The hypothesis being studied is that tomatoes grown on both red and silver co-extruded plastic mulch will produce a greater yield of marketable fruit as compared to those grown on black plastic mulch. It is also expected that the staked tomatoes will have a greater increase in yield than those not staked.
There will be two trial sites, one at The Ohio State University Waterman Agriculture and Natural Resources Laboratory in Columbus, Ohio, and the other at Henry W. Agle and Sons Inc. in Eden, New York. The trial plots at the New York site will consist of only 12 tomato plants (as to limit disruption of normal functioning of farm) spaced 28 inches apart. The planting dates will be as early as the weather provides in early to mid May. Production will be studied from the ten inner plants. The plants will not be staked, as that practice is not followed on the commercial vegetable farm the trial will be run at. The commercial vegetable farm, Henry W. Agle and Sons Inc., is located in the town of Eden in Western New York State. Four plots for each color of plastic will utilized. All fertilization, irrigation, and pest control will be the same as the rest of the commercial field, and will be recorded.
The Ohio trial site will consist of plots containing twenty-five plants at 28" spacing in rows eight feet apart. Once again only the fruit from the inner 10 plants will be studied. There will be eight plots for each color of mulch, and a bare ground trial will be added because of more free space. Four plots for each treatment will be staked, and four unstaked.
At both sites trickle irrigation will be the mode of irrigation on the ground level beds. The colors of four foot wide plastic mulch being studied will be red, silver co-extruded, black as the
control, and a bare ground treatment at the Columbus site. The fruit will be studied based on:
1. Quantity - number per plant and weight
2. Quality - scarring, uniform shape
3. Size - run through a commercial grader
4. Ripening date - harvested at marketable vine ripened color
Soil moisture tests will be recorded at 3, 6, and 12 inch depths throughout the field using Arometer Moisture Censors. This is the best method to indicate when irrigation is needed. Soil temperature at two and four inch depths will be monitored using Hobo XT Temperature Loggers from the Onset Computer Corporation, Pocasset MA 02554. This will show if there is a difference in ground temperatures under each color plastic. Tissue samples will be taken just prior to first fruit set, and just prior to harvest to be analyzed based on N, P, K, Ca, Mg, Mn, Fe, B, Cu, Zn, Al, and Na content.
Data will be analyzed to determine yield differences from fruit grown on red, co-extruded silver, and black plastic mulches. The data from the Columbus site will also be analyzed to see the yield differences between staked and unstaked treatments, and the bare ground plots as well. The information gathered will be made available to other commercial vegetable growers and university research and extension personnel.
Lamont, W. J. Jr. 1993. Plastic Mulches for the Production of Vegetable Crops. Hort Technology. 3:35-38. (Vol. III, No.1)
Naegely, S. K. 1998. Nematode Nemesis. American Vegetable Grower.
Orzolek, M. D. 1998a Use of Colored Mulches. Online. Internet. 16 October. 1998. Available: http://www.cstone.net/~agmulch/ref5html
Orzolek. M. D. 1998b Northeast IPM CRIS Reports: Environmental Modification For Extended Vegetable Production. Online. Internet. 25 October. 1998.
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