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Greenhouse Research

Nutrient Solution Management in Recirculating Systems

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CropKing Admin
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Hydroponic Bibb Lettuce

In recirculating hydroponic systems producing leafy crops, one of the main factors in the control of the grower is the frequency of tank changes (ie pumping out and turning over the recirculating solution). Since we generally manage the solution based on EC, we are assessing the total amount of solutes in the water. We don’t know the balance of each nutrient individually, so tank changes are carried out to try and maintain necessary levels of nutrients. Essentially, our goal is to change the nutrient solution often enough that we don’t have detrimental buildups of unused ions or depletions of important nutrients. Also keep in mind that different water sources have different background ion levels that can slow or speed up imbalances in the nutrient solution.
This tank change practice is really based on cost efficiency. There are nutrient solution management systems that have the ability to manage based on individual ions, but these are much higher cost than the typical systems installed in small to mid scale greenhouses. This hydroponics system cost savings comes at the price of more frequent tank changes that maintain a safe margin of nutrients in solution.

Cucumber Production- An Overview of OH numbers in 2013 and 2014

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CropKing Admin
Posted On:
Cucumber

Overview and Data Considerations

This data covers a couple of years of data (2013, 2014). So, the goal is to present to you an overview of crop yields and schedules.
Several of the main cultivars that we carry and that our customers use were trialed. However, these data do not represent all cultivars at all times of year, so comparisons across years are limited,
One of the most important things to keep in mind is that these trials were carried out in relatively small blocks imitating hydroponics at home. Our vine crop greenhouse is mostly dedicated to tomato production, so cucumber trials took place in units of 10-20 buckets on the western side of the greenhouse.
In some respects, these small sections of space dedicated to hydroponic cucumber production are similar to many grower houses, but it is important to remember that yields can vary according to light in different locations within the greenhouse. These trials were all carried out in Lodi, OH, so we cannot account for location variation that may be seen in other areas or seasons.
All of these trials were run with the plant maintained in an umbrella system. The majority of the crops were produced without pinching and were removed when the main leader reached the floor after traveling up to the wire and back down.

Summer 2014 Oakleaf Trial

Posted By:
CropKing
Posted On:
Lettuce

Seeding was done by hand into pre-moistened 1” x 1” x 1 ½” cubes of three different media (Grodan 200 ct rockwool, Oasis XL 162, and GrowTech 162). Seeds were germinated in clear water in seeding trays, and were transferred to the nursery and nutrient solution 3 to 5 days after seeding. Seedlings were produced in flowing nutrient solution in the nursery for an additional 10 to 12 days before transplanting. Due to the season, no supplemental lighting was provided during the seedling phase. After transplanting, plants were grown out in the channels for 25 to 28 days until harvest. The nutrient solution was continually cycled through the Fertroller where automatic pH and EC adjustments met programmed solution set points. The pH was maintained at 5.8 by the addition of dilute sulfuric acid. EC was maintained at 1.7 by the addition of concentrated fertilizer solution and source water. Tank changes were carried out every two weeks.

Branching out with Brassicas - Summer trial in NFT production in Ohio

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CropKing
Posted On:
Brassicas

In the greenhouses that I visit and crops I discuss with growers, it is clear that lettuce still fills a majority of plant spaces in the NFT system. However, we field an increasing number of questions about the many other leafy crop possibilities. Many of the other leafy options are in the Brassica family - cabbage cousins, essentially. These include kale, mustard, mizuna, and pac choi most commonly.

2014 Tomato Trials- Summer Sneak Peak

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CropKing
Posted On:
Hydroponic Tomatoes

For many of the producers that we serve, beefsteak tomatoes are a large majority of their production. However, trends in consumption and competition are increasing interest in specialty cultivars. From demand for farm to school salad bar items to farmers market mixed baskets, there are a range of options for small fruited and colored tomatoes. While visual interest and taste are critical in these cultivars, it is essential that production be adequate and relatively consistent over the season. These two questions are the reason behind this trial. Exhaustive yield data is not possible on the scale that we trial in our test greenhouse, but early evaluation is essential to begin to make suggestions for growers. So, this evaluation was carried out on small plots of fifteen cultivars to assess plant production throughout the season. These are preliminary trials to determine what cultivars to trial more extensively in the future.

Dealing with a Rexless Summer?

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CropKing
Posted On:
Hydroponic Bibb Lettuce

For growers, there exists something of a codependent relationship between them and their cultivar of choice. Due to uncertainties in seed production and demand, there is always the possibility of seed shortages or movement by the industry away from the ‘old faithfuls’. For bibb growers, the popular cultivar Rex is likely going to be less available this summer and early fall and so the questions of what other options to grow certainly are coming to our attention. While it is never possible to guarantee other cultivars will seamlessly replace current ones, CropKing’s trialing and research program is carried out to assist decision making in these areas. So, the best way for me to help growers decide what to grow is to show you what I have observed and measured in our greenhouses here in Lodi.

Investigating impacts of Electrical Conductivity in Nutrient Solutions

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CropKing
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In recirculating systems producing leafy crops, one of the main factors in the control of the grower is the nutrient solution electrical conductivity (EC). In many systems, total EC, rather than single elements are controlled due to economics. In most commercial systems using electronic controllers and dosing pumps, concentrated fertilizer solution is added to the nutrient solution any time the solution goes below target EC. So, maintaining consistent EC levels is fairly straightforward, the main question becomes: What is the best EC? The answer to this question is based on two separate factors. The first relates to maintaining needed nutrients in solution. Essentially, the important question is how close to calculated nutrient levels does the solution remain over time. If there are large amounts of ions already in the source water (sodium, sulfate, or calcium for instance), this can cause the nutrient solution to become out of balance more rapidly meaning that ideal ratios of nutrients are not maintained. The second factor involves the movement of water through the plant. At lower EC, it is easier for plants to take up and transpire water. Therefore, under high light and temperature, and low humidity, lower solution EC levels makes it easier for the plant to move water. So, the EC that we use in our systems needs to address these two issues: 1) Maintain adequate levels of plant nutrients, and 2) not stress the plant too much in terms of taking up water needed for transpiration.

Summer to Fall Mixed Leafy Trial

Posted By:
CropKing
Posted On:
Hydroponic Leafy Lettuce

While lettuce fills a large majority of the spaces in most greenhouse nutrient film technique (NFT) systems in the US, there are many other crops that can be profitable for growers in these systems. In addition to herbs, other leafy crops, such as kale, cress and endive are currently being investigated by growers to address specialty markets. In recent years, more growers are experimenting with these varied leafy crops. However, less is known about crop productivity and timing in relation to both cultivar and seasonal impacts. It is also important to note that unlike bibb and some other lettuce types, most kale, endive and cress are not specifically bred and developed for controlled environment production. So, there is a potential for greater seasonal variability in production than is seen in some of the common bibb lettuce crops. This trial was designed to evaluate a selection of kale and other leafy crops through a range of summer to fall conditions to evaluate their potential for greenhouse growers in the Midwest and Northeast. This trial obviously only used a portion of the cultivars available, but was intended to provide information for future more extensive trials.

Beefsteak Cultivar Trials- Part 2 (The Numbers)

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CropKing
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•This evaluation was carried out both to increase our knowledge
of several available beefsteaks and to provide information for
growers who may be considering these tomato cultivars.
Cultivars were obtained from a variety of seed suppliers to
represent a broad selection.
•Ten cultivars were trialed in small 4-plant blocks with two replications.
•The whole evaluation was completed in one row of a 22’ x 64’ x 10’ greenhouse
•Seeded 12/18 (All seedlings)
•Transplanted 1/14 (~ 4 ft2 per plant)
•First harvest 4/8
•Growing point removal 11/11
•Last harvest occurred on 12/16
•Data analyzed with Proc GLM and means difference letters calculated by LSD (different letters represent
statistically different cultivar averages)

Beefsteak Cultivar Trials- Part 1 (The Pictures)

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CropKing
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Greenhouse tomato production in the United States now encompasses a wide spectrum of fruit types and cultivars. Producers desire both attractive and distinctive crop cultivars to meet consumer demand, but consistency in both productivity and quality is still a key. Even with the increasing desire for specialty cultivars, many small to mid-scale growers still often establish and maintain their a large portion of their sales with beefsteak tomatoes. For many US consumers, high visual and taste quality in beefsteak tomatoes is the basis for greenhouse tomato price premiums. Because many greenhouse vegetable producers rely on a few specific cultivars, the production and reliability of those cultivars is essential. Additionally, over time their customers become accustomed to the taste and appearance of a certain cultivar and change must be carefully weighed. However, cultivars are sometimes discontinued or unavailable due to seed shortages, so being familiar with other options is quite important for growers. We generally encourage tomato growers to trial small sections of different cultivars on a consistent basis to remain up to date on new offerings and to be prepared if they are forced to switch cultivars. It is obviously important for us at CropKing to be familiar with cultivar options for growers. So, this evaluation was carried out both to increase our knowledge of several available beefsteaks and to provide information for growers who may be considering these tomatoes as options for their current crops. Cultivars were obtained from a variety of seed suppliers to represent a broad selection of cultivars available to greenhouse tomato producers.

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