Urban Agriculture: Rooftop Garden Update

November 27, 2016 | ProgressTH Part of what ProgressTH does is advocacy, the other part is putting ideas into practice. While our rooftop garden is small, it is a proof of concept with the ability to expand both at this particular location, and on other roofs nearby.

Growing Barrels 

Originally, we were using raised beds with ferroconcrete panels. This was labor intensive, time-consuming, and left the soil laying right on the rooftop. Having sourced relatively cheap 200L HDPE blue barrels, we ended up with a light-weight solution that easily allowed us to double our soil volume and keep the soil off the rooftop.

We cut the barrels in half, and the top (the barrels were purchased without lids) was placed on the ferrocement panels. For future expansion, we will use HDPE tarps to keep the soil from making direct contact with the roof.

Keeping out Pests

We used 22mm diameter PVC pipes and custom designed, 3D printed joints to create a triangular frame over the growing barrels. Over this, we can drape a variety of coverings including bird netting, insect netting, and shading cloth. Since we are planting tomatoes, we will use shading cloth as necessary when the seeds sprout.

Bird netting is being used to cover the entire growing area since we are also raising chili peppers and the birds here will otherwise devour them.

Irrigation, Automation, Data Logging 

During FARM HACK 1.0, we were on a team that developed a solar-powered moisture sensor and valve actuator for automated watering. The system suits a single growing barrel. We now need to scale this up.

We are considering using or developing a custom version of this solar powered lithium ion battery power bank. We will likely continue using an Arduino board, but may need to source and use a small DC water pump to distribute water to all 8 barrels (with the ability to expand in the future if necessary).

Eventually, using automation, remote monitoring, and data logging will not only make this particular project easier to keep track of, but it will allow us to expand onto other rooftops and minimize the time spent at each site. The ability to data log will allow us to see what works best, and what doesn't.

Eventually, things like custom moisture sensors, data logging solutions, automation, and other innovations we prove on the rooftop can be scaled up for rural farms we are in contact with.

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