About 400 meters from Brīvības Street, researchers of the Riga Agricultural Resources and Economics Institute (AREI) have been growing lettuce, peas, tomatoes and other goodies on the roof for the second summer. Colleagues of the Institute of Horticulture do exactly the same in field conditions in Pūre, Tukuma region. The goal is to find out whether food grown in the city is as good as food grown in a rural environment, said Linda Ieviņa, a researcher at AREI's Bioeconomy Department.
The buildings of Biķernieku Street can be seen on the right, huge linden trees tower above us on the left, and the traffic of Brīvības Street can be seen in the distance behind them. This is the view from the roof of AREI, on which various vegetables, greens, strawberries and even chamomiles are growing for the second season as part of the "Roof2Fork" project. The small garden is mostly watered with rainwater, which is collected from a nearby roof of about 20 square meters in size. "We use tap water only during longer periods of heat, unfortunately we cannot rely on rainwater, but we get to use it a lot," admits researcher Ieviņa.
In the urban roof garden, everything is grown in boxes and pots. At the beginning of July, juicy pea pods, curly lettuce, bows and basil are green here, the second round of radishes of this season is pouring out of the ground, expensive zucchini and pumpkin seedlings are swaying in the wind, the first tomatoes are starting to color. Potatoes have just been harvested, and the lettuce harvest was cut some time ago, which was so abundant that the scientists shared it with their colleagues and the local cafe: "They were very happy."
Some boxes have been created according to the researchers' individual interests: "For example, this is the Italian box - with rosemary and thyme. We call the one with mint the mojito box. The harvest has just been harvested, it was very good," the researcher shows the garden.
Experiment even with growing mushrooms in a shadier place - the top layer of the soil is covered with straw, which mushrooms like well and helps retain moisture longer.
They act the same in Riga and Pure
The main goal of the project is to study the quality of vegetables grown in the city and whether the urban environment affects the grown crop. In order to ascertain whether there is a special influence from the city, an analogue garden has also been created at the Institute of Horticulture in Pure. "We try to act as uniformly as possible, harmonizing everything in order to exclude other influencing factors," explains Ieviņa.
Modern technologies help researchers to provide the most similar growing conditions in Riga and Pure. For example, soil sensors measure moisture, and based on the data obtained, it can be judged whether it is time to water, so that the ground is equally wet in both places. There is also a small weather station swirling above one of the plant boxes. "From there, the data is sent to the website every 20 minutes, where we can look at it and compare it with the observations in the two gardens. Temperature, humidity and precipitation are measured there," explains Ieviņa.
The biggest problem is seagulls
With much more traditional methods, researchers are trying to limit one of the biggest problems of the roof garden - seagulls. "At first they ate cucumber seeds, there should have been a whole box of cucumbers. Later they started pecking what was being prepared. Then they had hidden pieces of bacon in the boxes," the researcher says about the mishaps. Now, above one of the boxes, a yellow rattling balloon flutters, which is supposed to scare the birds away, while in the strawberry box, red-painted stones have been placed to prevent the berries from being stolen - if the seagulls grab a hard "strawberry" once, they don't like it anymore. "Colleagues came up with an ingenious way to try to train the seagulls. So far there are still berries," Ieviņa shows the berry strawberry plants.
Next to the strawberries is a box with beans climbing up the wall. It was provided for the roof garden by a colleague who came to Latvia from France: "Her grandfather is a great gardener there, and the colleague decided to share her beans."
No big differences were observed between the city and the countryside
Indirectly, the researchers will also test the common belief that rural environments are clearly better: "The main association is still that cities are polluted and the countryside is a cleaner environment where everything should grow. Maybe a person is more comfortable in a rural environment than in a city, but that does not mean that an urban environment will affect plants." The final result will be clear at the end of the project next year, but the observations so far have not marked any real differences between vegetables grown in the city and in the countryside, says Ieviņa.
Also, what has been studied so far in the world about pollution in vegetables indirectly allows us to conclude that there should not be anything critical in products grown in the city, says Ieviņa.
In other words, plants take in the biggest pollution directly through the soil, but if they are grown in a clean substrate and not in urban land, then this risk should not exist. Also, previous studies show that raising the level of the garden - as in this study, growing on the roof - reduces all the potentially negative effects of the city.
The quality of the harvested crop is monitored by performing three types of laboratory analysis - measuring the content of nitrates and nitrites, checking the absence of heavy metals in the plants, and studying what chemical elements, including the desired ones, are in the composition. "There is also a separate analysis of plant health - it determines color, chlorophyll, vitamins, sugars and other nutrients. It also indicates how well the plant feels," explains Ieviņa.
Roofs - unused potential of cities
The researchers have put the emphasis directly on roof gardens, because it is a completely unused resource: "There are also a lot of flat roofs in Riga. There is a lot of potential, considering that the city and buildings are developing and different types of land use compete with each other. At the same time, there is we need to think about how to maintain green areas and vegetation. In that sense, roofs are a very good resource of space," emphasized Ieviņa. AREI's flat roof on Struktoru Street was also an unused resource until now, and at the same time it was also the main motivation that such a study could be carried out: "Our building has several roofs that were just standing for a long time and nothing was started with them."
The research focuses not on mass production, but on how the average citizen might act.
Therefore, one of the expected tangible results are guidelines for growing vegetables on the roof, which should be usable by everyone and also applicable to gardening on a balcony, terrace or in a small yard.
Why should urbanites grow?
Why should the townspeople grow anything when everything they need can be bought at the store around the corner? The researchers emphasize that there are a number of benefits. First of all, it is the opportunity to get fresh, self-grown food: "You know what it is and what you have put on it. You can easily access it, it is also economically very beneficial - of course, you have to pay for soil and seeds, but it can be cheaper , than buying in a store. Yields can be quite good."
The benefits of urban gardening are very diverse: "There is a lot of research that it reduces stress, it helps with relaxation, it's also physical activity - it's kind of like therapy. There are also different types of community gardens, which are a good way to build and strengthen the community. "
Show your city garden!
AREI researchers invite residents to participate in the study by showing their urban small gardens in photographs and answering some questions. You can send pictures and fill in the questionnaire here.
The researchers have also asked residents to get involved in the project, asking them to send pictures of their city gardens and tell why they are doing it. Residents have indicated that it is a good way to spend time with the family or to show children how a crop grows from a seed.
It should also be taken into account that food is consumed the most in cities, which in turn is associated with additional emissions. "Food is brought in from outside, and supply chains are often very long. In order to keep vegetables fresh longer, various substances are used - both in the growing and storage process," explains Ieviņa. In addition, if townspeople grew more food themselves, supply chains would be shortened and positive effects would occur on both urban and rural environments, promoting competitiveness, says the bioeconomy researcher.
Vegetables are also grown in Riga leaves
An important part of the project is also the study of different substrates or types of soil. In nine boxes, the researchers are testing three substrates where peat, which is considered an unsustainable resource in many parts of the world, is mixed with various other ingredients – perlite (a mineral of volcanic origin used in horticulture to better retain moisture in the soil and loosen it), coconut fiber and leaf compost. So far, researchers have not really observed that perlite really keeps the soil moist longer. Better results have been shown by expanded clay balls made from clay, which, unlike perlite, are produced here in Latvia.
Ieviņa singles out leaf compost as particularly promising, as it is not only an easily accessible resource and provides nutrients to plants, but it is also an opportunity to solve the leaf problem in the city.
The research uses urban leaf compost obtained from the Riga municipality, from which the waste has been sifted before and which has been kept for two seasons. Vegetables are also grown in Pūre in Riga leaf compost.
Both the leaf compost and all the substrates used are analyzed - to make sure that they do not contain any unwanted substances that the plants could absorb. "Leaf compost has great potential, especially when you think about the fact that people could provide it for themselves," explains Ieviņa.
The composition is also analyzed for the collected rainwater. Observations so far show that the city's rainwater is suitable for watering, but what is important is the surface on which it flows, says Ieviņa. Before the project, the researchers had set up an experimental garden on the roof of another institute's building, where rainwater flowed through a metal grate. "The analyzes showed that there are a little more metals than would be desirable. Therefore, attention should be paid to what surfaces the water flows on," says Ieviņa. The full conclusions of the study and whether city-grown products can be as good as those in the countryside are expected next year, when the researchers will have analyzed the data obtained during two gardening seasons.
Photo: Institute of Agricultural Resources and Economics