The aim of the project was to identify variety of greens that would grow and and remain marketable under quick tunnel season extension. Planting date affects the outcome and quality of greens in the tunnels. This attribute was investigated as well. A third concern was the affect of cold temperatures and low light levels on the nitrate levels in the leaves and if differing rates of fertility impacted these levels. High levels of nitrate can be toxic to consume especially for pregnant women and small children.
Having most of the crops transplanted by early September provided enough time for them to be large enough for sales in the late fall and early winter. The real problem lies if the late summer is extremely hot with soil temperatures in the high 70s F when germination and growth is spotty.
We tested different varieties of crops to see the best use of quick tunnels.
The lettuce variety, Jericho did well with moderately sized heads and sweet taste. Red Sails and Rouge d’Hiver had very pronounced color. Regiment and Renegade were the two spinach varieties that stood out. Getting spinach to germinate in the hot soils early in the September was problematic. For the kale, Winterbor and Redbor did well but like Swiss chard, these types of crops needed to have been started back in July to have the size big enough to produce larger harvests. The mustards Yukima Savoy and Mizuna and the brassica, Joi Choi were harvested at marketable sizes from mid-late September plantings. The stress from heat did affect germination of the earlier plantings somewhat and the other varieties bolted due to the stress. Broccoli rapi did satisfactorily though it needed to be well watered to reduce wilting and stress. Marketable bunches were harvested in November.
Arugula did not do well except for one location and a later planting. Cilantro had trouble germinating but some plantings overwintered and produced a crop later the following spring.
The fertility component of the trial did not show significant differences with the control. We believe this to be because the chicken compost which ended up being used for the trial throughout, did not have a great deal of time to breakdown. The hot dry conditions early on may have reduced biological activity as well as the cooler conditions that followed. Ideally, having the beds set up earlier in the season might have a greater impact on increasing nutrients available to the plants. With the fertility issue as it was, the measurements for the nitrate levels proved to be low for nearly every sample. If there was more time for the N to have been available for the plants, the nitrate test might have been different. Two samples did come back high. We believe that this needs more work to properly verify. Using multiple coverings was important for protection of the crops.
Keeping a row cover on only wasn’t enough to keep inside tunnel temperatures above freezing for a long enough period. Switching from a lighter weight cover to a heavier weight cover was important and then adding a clear greenhouse film cover provided the longest protection. Even so, the temperatures did drop below freezing inside the tunnel, probably due to limited heatable air volume but most of the overwintered plants survived to be harvestable later in the end of February and early March.
The use of season extension has increased phenomenally by farmers looking to enhance their marketing opportunities either earlier or later than the norm.In fact, the use of season extension has already surpassed some of the research questions I aimed to look at with this project. However, there are some things we did learn and new questions have arisen.
The aim of the project was to identify variety of greens that would grow and and remain marketable under Quick tunnel season extension. Planting date affects the outcome and quality of greens in the tunnels. This attribute was investigated as well. A third concern was the affect of cold temperatures and low light levels on the nitrate levels in the leaves and if differing rates of fertility impacted these levels. High levels of nitrate can be toxic to consume especially for pregnant women and small children.
Two factors affected the turnout of this project. One was growers’ busy schedules and changing time commitment on the farm. One of the growers had to drop out of the project early on due to time constraints and more reliance on high tunnels rather than the field use of Quick tunnels.
The second issue that came up was three consecutive years with very hot summers and early falls. The air and soil temperatures remained high into early October during all the seasons of the trial. In fact, the fall and winter of 2011 was one of the warmest on record. Spinach was very hard to germinate as was lettuce and several other greens. This caused a much later start and then when the light levels drop low, the plants did not reach optimal size.
As the project got underway, we altered the types of vegetable varieties trialed slightly and revised the fertility regime as well. This was done to make it easier for the growers to get the project underway.
A)What is the environment like under the low tunnels (ambient air temperature and soil temperature)?
B)What vegetable varieties work best grown under low tunnels?
C)How far into the late fall can leafy vegetables be grown using different covers?
D) As the temperature drops, what type of organic fertility produces the best crops?
E)As the temperature drops and light levels diminish, does nitrate toxicity in leafy green vegetables become a food safety issue?
The questions growers keep asking relate to timing, practices of protection against low temperatures but dealing with sunny warmer days, issues of light levels and ventilation, and what is a good nutrient program for the plants under these conditions. We will investigate timing of seeding to find appropriate dates for different varieties of leafy greens. Temperatures fluctuate with the weather. As seen with the current conditions this fall, cool wet weather followed by cold and below freezing night temperatures through October followed by mild sunny days in early November, how to manage the tunnels needs to be documented to optimize growth for the plants.
There are a number of fabric row cover of various weights available. Agribon 19 is a medium weight cover good to 28 degrees F with 85% light transmittance. Agribon 30 drops to 26 degrees F with 70% light transmittance. Agribon 50 goes down to 24 degrees F with only 50% transmittance. There is a a durable greenhouse plastic film with UV resistance. It offers a few more degrees worth of protection, but is harder to ventilate and looses more heat at night. What about combinations of covers being used or not used during the day or night depending on the weather? This will be investigated.
During the fall, soil temperatures drop. For organic farmers or where non-chemical fertilizers are use, release of nutrients to the plant roots is made available by the biological activity of the soil. This activity slows as the soil temperature drops. This can restrict nutrient accessibility by the plants. We need to see if there are differences in plant growth with different types of fertilizers used, when applied, and at what temperatures do we see affects readily change. We also need to see if some leafy greens tend to accumulate levels of nitrates under low light and low temperatures to a point of possible toxicity
The winter markets officially get started in November and some run to Christmas while others go nearly all winter and early spring. Quick tunnels were set up on 3 farms in western NY. There were 4 tunnels set up on two farms and one farm with one tunnel. Each tunnel will be 50-60 ft long (x4ft wide). The farm with one tunnel was interested in the variety trial part while the other two farms were cooperating on all aspects of the project.
The farmers have picked an assortment of greens to trial. These are spinach (36 days), arugula (40days), pak choi (40d), cilantro (55d), broccoli raab (rapi)(35d), an assortment of mustards (35d) and a brassicas (45-55d), and kale and Swiss chard (70d).
One tunnel was devoted to growing all of the varieties. We first looked at the influence of planting dates on timing of harvest and quality of the plants. This tunnel will be at least 60ft long and divided so that every 15 feet or so will seeded each week. There will be three rows per 12ft section made up of 4 varieties of vegetables per row. This equals a seeding every week for 4 weeks.
The monitoring will be for outdoor and under-tunnel air temperatures using max/min thermometers. Based on low temperatures and forecasts, the type of covers to use will be determined. If it is mild, no cover would be needed; cooler weather might require a fabric row cover; colder cloudy weather might require covering with clear plastic. Very cold weather might require both a plastic and fabric cover for protection. Variations in day and night time conditions will also dictate the strategies the growers will use. Soil temperatures in the tunnels will also be monitored.
Production of late season vegetables is dependent on several factors. There needs to be sufficient nutrients available to the plants. There needs to be sufficient warmth in the soil to allow for biological activity and root growth. There needs to be sufficient warmth for the plants under the cover.
The fertility issue is directly tied to soil temperature. In cold soils, biological activity slows. Under organic production practices, soil nutrients are released from organic matter through the activity of soil microorganisms.
We originally planned to compare different strategies for delivering the necessary nutrients to the crops. Poultry manure compost was used for all treatments. We at first proposed to use the following: the first treatment would be the incorporation of the compost into the soil one month before seeding of the crops. The second treatment would be incorporated right before seeding. The third treatment would be the use of liquid fish fertilizer. The fourth treatment would be the incorporation of Chilean nitrate just before seeding. The last treatment would be a control of no added fertilizer. Due to the farmers availability to the other fertilizers and what they had on hand, the poultry compost was the only one tried. The analysis was 8-4-3.
The data collected would provide us with information on:
Variety trial seeding dates and harvest dates along with comments.
Soil and air temperature during the growing phase of the variety trial and the fertility trial. This will provide us with the details of what is going on with the immediate environment in the root zone and around the plant leaves. Max/min thermometers were used initially but three broke early on (one was crushed by a deer) and were replaced. Two broke later on. To keep up with outdoor temperatures, NEWA weather data was used to fill in.
The types of covers will have affects on changes of the air temperature and eventually for the soil temperature. We took note of these affects.
For the fertility trial, we used refractometer measurements collecting Brix levels. Brix levels are the %sucrose in the sap. Low readings (compared with Brix chart) correlates to lower N. Twenty plants were chosen per treatment for testing. The results were graded as low, medium, or high with a number indicated as ideal based on the variety of plant (from the chart provided with the refractometer). Comparisons of the data over time should give us a clue as to how the plants are responding to the fertilizer regime of each trial.
Nitrate tests were conducted by collecting tissue samples and sent to the Cornell Nutrient Analysis lab for evaluation. We are looking to see if nitrates have accumulated to levels higher than the normal range for the variety of plant. From this we will then know if our N levels we started with were too high. Knowing this will be a red flag and we will warn growers going into late season production that they will need to keep N lower and that they should monitor nitrate levels in their plants.
Despite the setbacks, problems, and difficulties, there are some very useful points discovered and important information to share with farmers. Due to the heat, getting transplants and seedlings established was frustrating. The timing was totally set off when we tried to make 4 successive planting dates. The first section to review is how the varieties performed. Table 1 shows planting dates for transplants and direct seeding dates for the rest. Harvest dates are listed as well and this represents the date at which the first harvest begins. Some of the varieties would be harvested over a course of days and weeks.
The lettuce varieties trialed were Jericho, Rouge d’Hiver (both romaine-types), Red Sails (looseleaf) and Winter Density (Bibb). The first planting of these transplants struggled to get going under hot conditions. Despite losing nearly half at the outset, consistent watering helped settle the survivors in though the eventual head sizes were small. As the fall temperatures dropped, heads were able to be kept in the tunnel and picked as needed.
Farm 3 was in an area that had cooler temperatures and heavier soils that stayed moister. Establishment was easier, head size was better, and harvest dates were more in line with what was expected. All the varieties were trialed for at least 3 planting dates. The first planting date for all the varieties trialed were harvested in the shortest amount of time while each succeeding harvest was longer. Jericho: from transplant to harvest – planting date 1 = 35 days; planting date 4 = 79. Red Sails transplant to harvest – planting date 1 = 35; planting date 4 60. Rouge d’Hiver transplant to harvest – planting date 1 = 42; planting date 3 = 60. Winter Density transplant to harvest – planting date 1 = 50; planting date 3 69.
This pattern holds true pretty much for all of the different greens varieties trialed. Again, decreasing light is the limiting factor along with cooler soil temperatures. As the temperatures get colder, adding the first layer of row cover, Agribon 19 eliminates almost 20% of the light through the material. Couple this with decreasing daylight really reduces growth while increasing days to harvest dramatically.
Farm 2 had only tried one planting of Jericho and like Farm 1, did not have good results.
The second planting at Farm 1 looked to be the best of the 4 attempts in 2009. Growth was slower than in the spring season, probably having to do with diminishing duration of sun light. The harvest had the most heads of large size of all the planting dates. The heads were held in the cool conditions until needed for the opening of the winter market in November.
The third and fourth planting of Jericho took several weeks longer to reach even average size. The fourth harvest required that two heads be sold together to make up for the smaller size. Some of the heads were left in the tunnel to overwinter.
In March 2010, Jericho was harvested out of the tunnels. It wasn’t full sized but large enough to sell mostly as single heads. There was noticeable growth but it was later than estimated by two weeks. The quality was good and the decision to harvest was made based on worry of too much warmth and the increasing sunlight would cause bolting and bitter flavor.
For the 2010 fall season, late summer proved to be even hotter than the previous year. This set back seeding for transplants by several weeks. Farm 1 and 2 both had mid-November harvests off their first planting which actually did pretty nice. Heads were green and tall.
Farm 1 tried three more successive plantings with the second being harvested close to maturity in December while the third and fourth plantings were too small and attempts were made to carry them over the winter.
Red Sails did produce nice heads with rich color. The cooler temperatures latter in year brings out the reds darker than during warmer weather. The first planting was paler than the later plantings. This looseleaf variety by itself looked good but putting it up to the romaines like Jericho and Rouge d’Hiver, Red Sails didn’t appear to be as full and appealing.
Rouge d’Hiver had a sharp red coloration on the outer leaves with darker green towards the center. It took longer to grow but the heads were as large as or larger than Jericho for the first and second plantings. These also held up well overwinter into March. The 4th planting did increase in size in March but the harvest date was late into the month and the flavor was starting to get bitter. The mid-March harvest of the third planting date tasted far better.
Winter Density only had one planting date for Farm 1 in 2009 and 2010. This variety really does not like hot temperatures and had poor germination and slow growth. For Farm 3, the later plantings faired better.
Swiss Chard – Bright Lights takes a while to get going from seed in the heat. Production was slow and harvest of sizeable leaves only amounted so very small bunches. The lesson learned here is to get plants established in the spring and keep them growing throughout the summer and then cover them for late season use as mature plants from the beginning. In this way, time isn’t wasted waiting for the plants to gain size which is very slow as light diminishes. The larger plants also seem to survive better over winter than young plants do as well.
For kale, both Winterbor and Redbor, the same is true as with Swiss chard. Get the plants established in the spring. It takes too long to get any size to the plants to make it worth while harvesting for the amount of space it takes up in the tunnel. The plan should be to have kale, chard, cutting celery, and parsley all started in the spring in their own separate row together. When the fall comes, build a tunnel over the established plants and protect them for the late season. Then harvesting would be coming from full sized plants and they also overwinter under protection for late winter and early spring harvests.
Both varieties grew once the weather cooled down. The colors were dark. The textures were crisp and the flavor was sweeter with the lowering temperatures. The size of the plants were small, however, making them not very productive overall.
Spinach: the varieties were Space, Tyee, Regiment, and Renegade. Spinach geminates poorly in warm weather and not at all in hot weather. Getting stand establishment was slow. Daily irrigation was needed to get any germination after several attempts at seeding. Many growers now transplant spinach to avoid direct seeding. So looking at the initial results doesn’t show anything great for the first two planting dates in 2009. The later planting dates did better with full sized plants. Regiment and Renegade produced the largest bunches.
Mustards: the varieties were Mizuna, Tat soi, Yukima Savoy, and Pak choi – Joi Choi. Again, seed germination was poor initially. The stress on mustards results in bolting Tat soi appears to be the most sensitive to this. The second, third, and fourth seeding dates had better germination and plant growth for all the varieties. Mizuna and Yukima Savoy did well with full growth. Yukima Savoy also survived overwinter. Joi Choi did well with the second and third seeding dates producing full sized heads. The fourth planting dates had smaller heads but were sold as “baby choi”.
Arugula and Cilantro – Santo also failed miserably due to the heat early on. Later seedings of arugula germinated and grew but not as well as with spring plantings for Farm 1 while it did better at Farm 3. The plants at Farm 3 grew to full size and had several cuttings harvested.
Santo cilantro eventually germinated once the temperatures cooled down but germination was sporadic. This might do better planted in earlier and in the shade of another crop that could be harvested out of the way in time for the cilantro to take off in mid-September. Something interesting to note was that the cilantro did germinate in March after overwintering and produced a very strong early season crop.
Broccoli rapi – Sessantina: This variety did well as long as it was kept watered. Stress causes bolting. The plants can be harvested for greens or shoots (small broccoli florets). The plants sized up in reasonable time. The flavor improved with cooler weather. Getting customers to try this vegetable green and use it in cooking is a challenge but with the right market, rapi can be a good choice for season extension production.
Tunnel Temperatures and Covers
Table 2 shows the temperature data for three sites in 2009/10 and 2010/11. The data is consolidated from piecing together what we could collect trying to overcome problems with two batches of max/min thermometers purchased that were defected. So instead of showing three sets of temperature data the best display of the data is to put it together to give what the fall and winter looked like over two seasons. Some weather data was also collected from the NEWA weather site for the area to fill in a few of the dates for outdoor temperatures.
The plan was to cover the tunnels using the thinner row cover fabric, Agribon 19. This is rated to reduce sunlight by 19%. We would use this while the temperatures were in 40’s during the day and 30’s at night. By mid-November, the Agribon 19 would be replaced with Agribon 30. It would offer more protection against the cold though it would reduce the light by 30%. By early December, there wouldn’t be enough sunlight to really allow for plant growth so at this point protection against freezing would be the most important. Covering over the row cover with the greenhouse sheeting would then be used. This would trap more heat under the tunnel, cut down wind-drying issues, and offer a thicker blanket to hold the plants over for harvest then overwintering for the future harvest in late February and March.
In 2009, the night temperatures were dropping low enough to warrant covering with Agribon 19. With warm sunny days, the covers were removed. The row cover was held down by sand bags. After a week or two of covering and uncovering, the Agribon was left on. The heat and humidity increased inside the tunnels and the growth improved. Soil temperatures were high to start and slowly dropped over the weeks through mid-December (8/15 – 74Fo; 12/29 – 50Fo.).
On Dec. 5, the Agribon 19 was replaced with the heavier weight Agribon 30 and the clear greenhouse poly sheeting. This offered extra protection for the plants and moderates the lowering soil temperature. As the weather really turned cold, the soil temperature dropped quickly into the low 30’s.
One of the main problems encountered occurred on 1/11. The edges of the row cover became solidly frozen to the ground. This makes entering the tunnels impossible without ripping the poly sheeting or tearing the fabric. Checking the soil temperature inside the tunnel wasn’t possible during these weeks. Harvesting greens also was halted.
The second major issue that occurred repeatedly was high winds pulling off the row cover, especially on farm 1 and 2 which ran their tunnels right through the winter. The sand bags seemed to be heavy but as the winds caused the row cover to ripple, the effect was to pull the edges of the cover out from under the sand bags little by little. With more slack in the cover the wind speed forces the row cover to pull itself totally free and flaps around. If it snows, then the cover gets buried making it harder to pull back on. The cost of labor for recovering the tunnels adds up when this happens. The quality of the plants decreases from freezing or wind injury. All that effort exerted to just lose plants to the wind. Eventually, to fix this problem, sand bags on either side of the tunnel were tied together with the cord going over the tunnel. With sand bags at the base of every hoop, the cord goes over the tunnel to the corresponding sand bag. The cord is just tight enough to prevent the row cover from rippling and flapping in the wind.
What we discovered was that switching from the lighter row cover to the heavier and adding the greenhouse sheeting provided important protection for the plants. One small tunnel was set up for on one farm for other greens and was covered with only Agribon 19 for the winter. The inside temperature dropped frequently into the low 20’s or lower and the greens froze solid. Many of the plants were damaged or died. For the tunnels with the heavier row cover and greenhouse plastic allowed the plants to survive in good shape (marketable shape). When the temperature and light levels rose in late February and early March, growth resumed. By mid to late March, marketable sized plants were ready again.
The last segment we examined was nutrient availability and accumulating nitrates in the greens. We set up a tunnel with four sections having a control of no added fertilizer and the next three with increasing amounts of fertilizer. To get quick ballpark results, a refractometer was used. Refractometers give a reading of sugar and mineral levels in plant tissue. Two farms participated in this segment of the trial. Readings were taken in November, December, and March for those vegetables that were present at that time for those farms. This data is found in Table 3.
Comparing the readings with a chart of tested vegetable Brix values (chart available with refractometer and also available from Peaceful Valley Farm Supply www.groworganic.com) , a determination of low, average, or high percentage of soluble sugars and minerals are present. Since there is a direct relationship between the sugar levels and N accumulated in the plant tissue, this will provide an estimate of nitrate in the leaves.
Collecting leaves and crushing them to get sap to place into the meter gives a fast reading. The meter is first calibrated using distilled water to get a reading of 0. Several drops of plant sap is added to the meter plate and closed. Holding the meter up to the light, refracting it gives a manual reading of numbers ranging from 1-26.
From each farm, four samples of leaves were taken from the most mature variety in mid- November as a base line. Another round of samples were taken in mid-December. It was felt that by this time, the plants would have taken up the most nutrients they were going to since the soil temperatures had dropped. Light levels were about at their lowest points. A follow-up round of samples was taken in early March to see if there were any changes.
The results of the Brix readings for November ranged low to moderate. Mizuna ranged from 5-7 in November averaging around 6. In December the range was 5-9 averaging around 7. In March the average was still 7 though the range was 6-8. The chart lists 6 as average and above 10 as high.
With spinach, Regiment was tested. In November, the range was 5-7 averaging close to 6.5. In December the range was 6-8 averaging about 7. For March the range increased to 7-9 averaging 7.5. There was no chart listing for spinach.
Winterbor kale was tested and in November ranging 7-10 averaging about 8.3. In December the range widened to 7-11 with an average around 9. Then in March the average stayed around again with a range of 7-10. The chart lists kale with an average of 10.
Lettuce had a range of 4-8 in November with an average just under 6. In December the range was 6-9 averaging around 7.7. In March the range was 5-8 with a lower average about 7. The chart list lettuce with an average of 6 and above 10 as high.
Arugula ranged from 5-8 across the three testing periods averaging around 6. The average of 6 is found on the chart.
Swiss chard ranged 6-8 and the chart lists the average at 8.
Leaf samples were also collected in December for both farms (only one set from one farm in January) and sent off for tissue analysis. The tests will provide the levels of nitrate in ppm found in the samples. Having numbers in the 4200 – 4800 range suggests that nitrates are in the acceptable levels. Anything below that is low and above is high.
The results returned did not vary too widely for the most part. Mizuna had all but two samples at or below average. One of the two outlying samples was just above 5200 while the other was nearly 8000. The January samples were at or below average.
For spinach the samples were at or below average.
For kale, the samples were generally average or below with a couple of samples slightly above average. This was true for the January samples as well.
Lettuce had the lowest readings of all the greens sampled. Most of the samples were well below average with 8 readings below 3500. One reading was 916.
Chard and arugula were also mostly below average with arugula more on the low side of the scale.
Pulling all this information together basically confirms that despite adding more N for fertility, nitrates are not accumulating to above average levels in the leaves. This is good. We don’t want a toxicity issue developing as more farmers turn to season extension production. Since there were several samples did have higher than readings, the issue of nitrates should be made of aware to growers. Perhaps the organic fertilizer used did not fully break down and was made available to the plants due to reduced soil biological activity. If high rates of fertilizers are used earlier than we had applied them or if a more soluble form was added, then nitrates might become an issue.
Using a refractometer might be a useful tool if baseline readings are first made. Then if the is sharp rise in Brix readings, then a follow up tissue sample analysis should be done to err on the safe side. Many stage agricultural colleges provide tissue analysis services as do several private labs that do soil sample analysis.
What Was Learned
Hot weather will severely set back direct seeding which will lead to later harvest times. Extra irrigation, shade cloth usage, or using transplants instead of direct seeding may be required to get things going on schedule. Quick maturing varieties are best for harvesting in Nov-Dec. Later planted varieties will require good protection to overwinter. Overwinter varieties that are close to maturity. When it does get warm enough in the late winter and early spring one isn’t waiting for further plant growth to occur before harvesting.
Tunnel Temperatures and Covers:
Tunnel temperatures drop quickly once extended cold weather sets in. If the late summer or early fall was cool to start with, unlike our trial period, then soil temperature would have started out lower. To protect the quality of the crop, adding multiple layers is crucial. We know that clear greenhouse covers lose too much heat at night. Adding a fabric cover cuts heat loss down. To overwinter greens, the heavier the cover the better but don’t expect any plant growth. Heavier covers reduce light levels as well.
The big drawback to quick tunnels is the small air volume. High tunnels have more air to heat resulting in a better growing environment. Quick tunnels seem to offer good protection for established plants like kale, chard, cutting celery, and parsley. It offers a low cost system for growing quick growing varieties like spinach, mustards, rapi, baby lettuce, and cress. Quick tunnels also offer an area to protect overwintering greens for harvest in late winter and early spring like kale, chard, and varieties grown in the fall close to maturity like lettuce, spinach, and rapi.
Two major drawbacks were wind and freezing covers to the ground. The wind in the winter proved troublesome in pulling off covers. More effective measures are needed to reduce this problem. Exposure to drying winds will severely damage plants. Having to try to recover tunnels in the middle of January isn’t much fun either. Having the covers freeze to the ground, especially early on in the winter season will limit the access to harvesting the crops. Finding ways to diminish freezing is needed that is cost effective.
The results show that nitrates were not an issue for the crops grown. Monitoring is necessary to be on the safe side especially if soil fertility is high to start with or quickly available N is added to the plants. Using a refractometer and or follow-up tissue nutrient analysis testing should be considered.
Education & Outreach Activities and Participation Summary
An on-farm workshop was held in October 2010 on Kurt Forman’s farm in Palmyra, NY. Twenty six farmers attended where we had talks on using quick tunnels, varieties trialed, viewing of tunnels in the field, as well as hoop bending demonstration and training for growers.
On January 12, 2012, I gave a presentation on using quick tunnels for production. This was a season extension workshop. Some of the data and what we had learned was presented to an audience of 42 farmers in Canadaigua, NY.
On March 5, 2012 at Alfred State U. in Alfred, NY, I gave a presentation at another season extension workshop in the deep southwestern part of the state. There were 18 growers present where I presented how to build and use the tunnels based on the information we learned from the trial.
This project did not specifically look at the cost of building or operating tunnels. This is an important question however. In a follow up conversation with one of the farmers, this point was brought up.
Our costs per tunnel based on materials and the type of covers used ran from $200/100 ft length with Agribon 19 to close to $600 per 100ft tunnel using Agribon 30 and greenhouse sheeting. With the beds at 4ft widths x 100ft lengths, that is 400sqft. Sales for greens in the late season average $3/sqft so an expected sales of over $1000 for the entire crop is possible per tunnel.
From our workshops we have learned that quite a number of farmers are moving into season extension. Many started out with quick tunnels and have moved to caterpillar and/or high tunnels. Some are using just quick and caterpillar tunnels because of the lower cost, moveability of the structure around a field, and for just using them in the fall and then again for early spring production. Others have moved to high tunnels for the high value crops while using quick tunnels to protect important but less valuable greens.
Below are two follow-ups with Kurt Forman and Ed Fraser who worked longest with the project. I think they really speak to the use of quick tunnels and to the work that still needs to be done for season extension.
Ed Fraser:Hi Robert,
I was able to successfully extend the season for kale, lettuce, spinach and asian greens for the first year that I used the quick hoops. The only real issue I had that year was that the row cover blew off a couple times. We now use heavier sandbags and tie the ends tighter to stakes.
The following Spring, I was able to put in more spinach transplants very early and they did very well.
Season extension on my farm now happens in the high tunnel and under quick hoops as well. I have dirct seeded beets and turnips in under the quick hoops. They are doing well depite the fact that the deer have torn some of the row cover and been grazing on the beet greens in one of the hoop beds. Also, I think that I should have done a stale seed bed to lessen the weed pressure. Lots of witner weeds. I am expecting to harvest some of the turnips and beets in the spring.
Kurt Forman: The biggest challenge I had was keeping the cover (row cover or plastic) down on the hoops. I couldn’t keep it on the first year very well and in the second year, even with “better” hold downs, the cover still blew off. They are rather labor intensive, so I would have to charge significantly more for my produce to make them pay. Perhaps I have been too shy to up the price to cover my added labor and material costs. I think that the hoops would work well if I could keep the covers on since wind seems to be the biggest enemy to keeping the plants going through the winter, especially greens.
Have any cost of production studies been done, reflecting added costs of labor and materials?