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Season
Extension: Using Row Covers and Plasticulture to Produce an Earlier Harvest and
Greater Yields
Table of Contents
4.0 Conclusions and Discussion
4.1 Discussion
of Results for Individual Crops
4.2 Additional
Factors Affecting Experiment Results
4.3 Additional
Costs and Labor
7.0 Signature of project leader and date
Table 1.
Experiment yields from each treatment.
Figure 1.
Cumulative experiment yields for each treatment.
We compared the effects of red and black plastic mulch with and without row cover to soil without row cover for tomatoes, peppers, eggplant, and melons. Our objective was to determine whether earlier harvests and greater yields could be achieved by planting early, using row covers and plasticulture to protect plants and enhance growth. We succeeded in getting greater yields by as much a month earlier with plastic and row cover compared to soil. Three cultivars of tomato, eggplant and pepper were used and two cultivars of melons. We recorded each harvest date and weights of harvest for each treatment. Some treatments produced yields of double and triple the amount produced on soil. The best treatment to use will vary for each user depending on the importance placed on factors such as earliness, overall yield, or cost of materials.
We started all of our transplants in a green house. We ordered our SRM red and black plastic mulch, drip tape (8 mil t-tape) and Agrofabric Pro 19 row cover early enough that we had it on hand. We had compost spread in May and then had the field plowed and disked. On May 17 we borrowed a mulch layer and began laying mulch and drip tape as soon as the field was finished being disked. The mulch layer was pulled behind our tractor. One person drove and another person watched to make sure the mulch was being laid correctly and shoveled dirt on any spots that were missed or not fully covered. Level field preparation can not be stressed enough to make the mulch layer work well. We chose 4-foot wide mulch and used normal black mulch and SRM red. We laid drip tape on the surface under the mulch.
We bought a water wheel transplanter ($2400 - not grant money) to help speed up the transplanting and to avoid the physical punishment of hand transplanting. The transplanter pokes a hole in the mulch and creates a hole for the transplant. It fills the hole with water, which helps the survival of transplants.
Transplanting began on May 19th, which was 4 days later than we had hoped to get started, and we finished by the 21st. We normally use June 1 as our frost free safe date although it has been known to freeze in June. We started with tomatoes and then moved to peppers and eggplant. We transplanted melons last. Had it frozen, the added benefit of row cover would have been tested.
Once the transplants were in we installed wire hoops about every 3 feet on the 4.5 rows getting row cover. We decided to use sand bags filled with dirt to hold down the row cover. Filling and moving all the bags was a big project. We think it worked better than using piles of dirt to hold down the row cover since it did not tear the cover and a shovel was not needed every time the cover was moved. The bags were easy to move for inspections, pollination and for removal of the row cover. The Agrofabric Pro 19 worked well but began to deteriorate in 60 days, which was much more quickly than we thought it would.
Once everything was planted we kept it weeded. Our farm is certified organic so we did not use any herbicides, pesticides, or chemical fertilizers. The plastic mulch required less than 1/3 of the weeding time of the bare soil rows. We did need to carefully remove weeds, especially bindweed, that would grow up through the holes in the much that were made for the transplants. The sides of the mulch where soil had been mounded up to hold it down were difficult to weed. We had to hand pull the weeds since a hoe punctured the plastic. We would like to try a flame weeder in the future to control the weeds on the sides of the mulch. Amazingly, we only used the drip tape to water when the transplants were first planted. It rained so often that we never watered again the entire season. We removed the row cover earlier than anticipated because it was tearing, the plants were growing through it, and we had pollination concerns. It would have been nice to have been able to re-cover the plants in the fall to protect from frost. This was not practical since the cover was shredded and the plants had grown so large that the cover would not have been big enough. The plants on plastic grew much larger than we had anticipated and grew larger than any previously grown on our farm.
For the experiment we planted five 365 foot rows of tomatoes and melons. For the peppers and eggplant 91 feet of each were planted per treatment. Each cultivar of each crop was trialed on red mulch, red mulch with row cover, black mulch, and black mulch with row cover. Bare soil was used as a control for comparison.
For tomatoes and melons 20 plants of each cultivar for each treatment were selected and marked twice on each plant with florescent surveyor tape. For peppers and eggplant 10 of each cultivar on each treatment were selected. We harvested every few days once the crops began to ripen. We carefully picked from the marked plants in each treatment, weighed and recorded the data. We personally did almost all of the harvesting from the plants in the experimental section of the farm to try and prevent mistakes. We were concerned that if we had somebody helping who was not integrally involved in the experiment that non-experiment plants would be included or experiment plants would accidentally be picked but not recorded. In the grant proposal we agreed to pick only fully ripened fruit. Melons were picked at full slip, tomatoes at full red, peppers at full red and eggplant at what we felt was a reasonable size for that cultivar. Damaged or otherwise un-sellable fruit was not accounted for.
Below are diagrams showing the experiment field layout.
Tomatoes
Tomatoes were planted 7 inches off center in rows with 2 feet between plants and 5 feet between rows.
|
Tomatoes |
Covered,
Black Plastic |
|
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|
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Cultivar
1 |
(Early
Cascade) |
|
Cultivar
2 |
(Striped
German) |
|
Cultivar
3 |
(Fantastic) |
|
|
|
|
|||||||
|
Tomatoes |
Uncovered,
Black Plastic |
|
|
|
|
|
||
|
Cultivar
1 |
(Early
Cascade) |
|
Cultivar
2 |
(Striped
German) |
|
Cultivar
3 |
(Fantastic) |
|
|
|
|
|||||||
|
Tomatoes |
Covered,
Red Plastic |
|
|
|
|
|
|
|
|
Cultivar
1 |
(Early
Cascade) |
|
Cultivar
2 |
(Striped
German) |
|
Cultivar
3 |
(Fantastic) |
|
|
|
|
|||||||
|
Tomatoes |
Uncovered,
Red Plastic |
|
|
|
|
|
||
|
Cultivar
1 |
(Early
Cascade) |
|
Cultivar
2 |
(Striped
German) |
|
Cultivar
3 |
(Fantastic) |
|
|
|
|
|||||||
|
Tomatoes |
No Mulch,
No Cover |
|
|
|
|
|
|
|
|
Cultivar
1 |
(Early
Cascade) |
|
Cultivar
2 |
(Striped
German) |
|
Cultivar
3 |
(Fantastic) |
|
|
<------------------------------------------------------------ |
365 ft -------------------------------------------------------------------------> |
|||||||
Peppers
and Eggplants
Peppers and eggplants were planted 18 inches apart in rows with plants staggered 7 inches off center and with 5 feet between rows. Cultivars used for eggplant were Orient express, Rosa Bianca, and Dusky. Cultivars used for peppers were Ace, Lady Bell, and Lipstick.
|
Eggplant |
Peppers |
Eggplant |
Peppers |
Eggplant |
Peppers |
Eggplant |
Peppers |
|
|
Uncovered |
Uncovered |
Covered |
Covered |
Covered |
Covered |
Uncovered |
Uncovered |
|
|
|
|
|
|
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|
|
|
|
|
<--------------------Black
Mulch 183 feet---------------------> |
<------------------- |
Red Mulch
183 feet--------------------> |
||||||
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Eggplant |
|
Peppers |
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Uncovered |
|
Uncovered |
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|
<------------------No
Mulch 183 feet -------------------------> |
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Melons
Melons were planted 7 inches off center in rows with 2 feet between plants and 10 feet between rows.
|
Melons
Covered, Black Plastic |
|
|
Cultivar
1 (French |
Cultivar
2 (Roadside) |
|
|
|
|
Melons
Uncovered, Black Plastic |
|
|
Cultivar
1 (French |
Cultivar
2 (Roadside) |
|
|
|
|
Melons
Covered, Red Plastic |
|
|
Cultivar
1 (French |
Cultivar
2 (Roadside) |
|
|
|
|
Melons
Uncovered, Red Plastic |
|
|
Cultivar
1 (French |
Cultivar
2 (Roadside) |
|
|
|
|
Melons
Uncovered, No Plastic |
|
|
Cultivar
1 (French |
Cultivar
2 (Roadside) |
|
<--------------------------------------------------------365
feet ------------------------------------------------------> |
|
At the end of the season we had to remove all of the drip tape and plastic mulch. Originally we hoped to reuse some of the mulch and drip tape. The mulch had holes in it and was deteriorating from sunlight. It would not be cost effective if it was even possible to reuse the mulch. The drip tape may have been salvageable but we were not careful enough. The mulch was covered in rotting smelly tomatoes and had mice living under it. The melons plants had withered enough that the mulch could be pulled and the plants would disintegrate. On the tomatoes each plant was cut off at the base so the mulch would pull free. On the peppers and eggplant we tore the mulch up in such a way as to leave the plants standing. The mulch pulled free with a bit of work and some good gloves. It took about 35 minutes to remove one 365 foot row of mulch and drip tape. On soil where the drip was buried 3-4 inches it took almost as long to just remove the tape. It has been recommended to use a bush-hog mower to cut the plants before removing the mulch.
We harvested the experiment and weighed the yield several times each week and the results are presented in Table 1. For each cultivar, all the ripe fruit was harvested in each treatment and weighed separately according to treatment. We did not attempt to record the harvest from individual plants. It should be noted that only marketable vegetables were harvested. Produce that had significant hail, insect, sun, or other damage and was therefore not sellable was not included in the experiment harvest. Experiment yield results are also shown in Figure 1. The average cumulative yield per plant is shown over the course of the harvest period.
We also photographed the plants in this experiment at several points during the development of the plants. A significant difference in the development of the plants in different treatments is visible, especially in the earlier stages of growth. (see photos)
The results from our experiment clearly show that increased yields and earliness can be achieved by using plastic mulch and row cover (see Figure 1 and Table 1). However, there was no single treatment that was definitively the best for all the crops and cultivars. In this section we will discuss the results for each cultivar then discuss other factors that we believe affected the results and should be considered when evaluating the different treatments to achieve your individual goals.
Eggplant
The first crop in our experiment to produce ripe fruit was eggplant. In general, eggplant produced the greatest yield on red or black plastic with row cover. These treatments provided significantly earlier yields with some eggplant cultivars, but not others. The following table is a summary of eggplant yields:
|
|
|
Red w/ cover |
Red no cover |
Black w/ cover |
Black no cover |
Bare Soil |
|
Dusky |
Total yield/plant (lbs) |
3.6 |
3.0 |
2.8 |
2.0 |
1.7 |
|
Dusky |
% increase over bare soil |
106% |
74% |
63% |
15% |
0% |
|
|
|
|
|
|
|
|
|
Orient
Express |
Total yield/plant (lbs) |
2.5 |
1.9 |
2.7 |
1.4 |
1.9 |
|
Orient
Express |