Two weeks ago we hosted our second annual Food Systems and Public Health course in partnership with the Johns Hopkins Center for Talented Youth (CTY) at the Cylburn Arboretum. Six CLF staff members spent the day with 15 talented middle- and high-school students and their parents, and worked to define the food system, acknowledge harms, and develop a sense of hope for changing the world through the way we grow and eat our food. Read More >
Researchers at the Johns Hopkins Center for a Livable Future have conducted one of the first large-scale international surveys of aquaponics practitioners. For those who’ve noticed the buzz around aquaponics, the findings are not surprising. First of all, more than 800 people responded to the voluntary survey, which in itself demonstrates enthusiasm. Second, the results show that most respondents are new to the field, and third, that most of them are practicing as hobbyists. The survey has uncovered a couple of big themes in the field of aquaponics: enthusiasm and Read More >
Every aquaponics practitioner shares the same fear: that one morning all the fish will be floating on the water’s surface. Although tilapia is one of the hardiest species raised in aquaculture, they still depend on well-managed water quality. Here are some lessons we have learned at the CLF Aquaponics Project.
Monitor Your Water Chemistry
Aquaponics is a living system that depends on a series of chemical and biological cycles and physical treatment of waste (i.e., filtration and sedimentation) to maintain healthy water. We regularly test for several parameters: pH (daily), ammonia, nitrite, nitrate, and alkalinity (weekly). With the help of bacteria, ammonia from the fish waste is converted into nitrite and then nitrate. Ammonia and nitrite are both highly toxic to fish, and we monitor these levels to ensure that they are Read More >
For many farmers, summer is the time of peak production and abundant harvests, but at the CLF Aquaponics Project our harvests peak mid-spring and start to decline as summer approaches. Farming is a learning process; and higher pest pressure coupled with hot temperatures in our hoophouse has made finding ideal summer crops a challenge.
Leafy greens and herbs are naturally some of the best crops for an aquaponics system, because they thrive in a nitrogen-rich environment. However, many of these greens prefer cooler weather, and as the temperatures in the greenhouse climb past 100 degrees Fahrenheit, even heat-tolerant chard gives up. We’ve found that many of summer’s star crops in the field, such as squash, tomatoes, beans and okra, simply do not produce well in our aquaponics system. The reason for this likely lies in the fact that these fruit-producing crops require high levels of potassium and phosphorous in comparison with leafy greens to encourage reproductive growth. Read More >
The greenhouse enclosing the CLF Aquaponics Project affords us many advantages over farming in a field, including season-defying winter growing potential. However, even inside a greenhouse, a farmer’s control over nature is only an illusion. This is most evident when it comes to pest control. Despite our plastic roof, or perhaps because of it, we attract swarms of insect visitors year-round.
While there are many different greenhouse designs, including some that feature bug screening and double-entry doors for biosecurity, our greenhouse is far simpler. It has roll up sides Read More >
Visitors to the CLF Aquaponics Project often ask, “As farm manager, what do you do all day? It looks like the system runs itself, right?” Although an aquaponics system, if managed efficiently, can require less labor than a soil-based farm, the lush rafts of swiss chard, kale, and sorrel need help to develop into quality produce. Every plant is seeded, transplanted, managed for pests and diseases, harvested, and sometimes even pruned or trellised as it grows. However, the trickiest part in managing any farm is in the planning that takes place behind the scenes.
A farm plan will determine the success or failure of a business; and since every piece of land, microclimate, and market is slightly different, it can take years of experience in one place to get right. At the CLF Aquaponics Project, we are continually learning Read More >
I’ve grown vegetables for most of my adult life, and I have become accustomed to eating a lot of locally produced food, either resulting from my own farming endeavors or a trip to the local farmers market. I feel fortunate to be able to easily source the majority of the vegetables on my plate from small-scale, local growers, or grow them myself. However, despite growing up in coastal communities, there have only been a handful of times in my life when the fish I ate came from a local source. Last Tuesday, I was provided with an opportunity to eat fish produced in Baltimore City when we harvested 20 pounds of tilapia from the CLF Aquaponics Project.
On the surface, the aquaponics system appears to be a replica of a natural ecosystem where the word “waste” is an artificial concept. The fish don’t excrete waste, they excrete nutrients, and the plants take up these nutrients, filtering the water for the fish. However, in our earlier post “When the Fish and Plants Don’t Get Along,” we discussed how solid accumulation on the bottom of the plant beds can lead to poor water quality. To prevent this, we employ clarifiers after the fish tanks and before our plant beds; these tanks are designed to slow the water enough to allow solids to settle. Every day we drain the sediment from the bottom of the clarifiers to remove a total of 12 gallons of muddy, solid-filled water from the system. Just because we don’t want these solids sitting beneath our plant rafts, doesn’t mean they are a waste product. In fact, the solids are loaded with valuable Read More >
All plants start out from seeds on the farm. We raise seedlings in coconut coir media and after 2-4 weeks we plant them in net pots in hydroponic beds. The healthy establishment of our seedlings is vital to the aquaponics system. High germination rates and vigorous seedlings growth rates help conserve valuable farm resources, like space, time, and money. This fall, I studied methods to improve germination rates and seedling growth of lettuce by testing whether watering with natural fertilizers and probiotics affected seedlings differently than watering with a control of aquaponics system water.
To test this hypothesis we set up a study that we informally dubbed the “Seedling Trials.” We used three different nutrient solutions: Rock Phosphate Fertilizer (Dr. Earth, Winters, CA), EM-1 Microbial Inoculant (EMRO, city) Read More >
It’s easy to get excited about aquaponics. On the surface it seems simple: the waste from the fish is recycled into valuable nutrients for the plants, while the vegetables purify the water for the fish. Aquaponics, like any form of agriculture, is dynamic, changing with the seasons and over time. As the fish and plants grow, their needs change and shift the balance. Read More >