Demonstration rainwater harvesting system, gardens established at AgriLife center

AMARILLO – With the landscape and rooftop availability at the Texas AgriLife Research and Extension Center in Amarillo, Nich Kenny, Texas AgriLife Extension Service irrigation specialist, determined it is the perfect demonstration plot.

“We’ve been working on a project where we will collect rainwater and demonstrate multiple types of gardening plots, as well as develop turfgrass demonstration plots,” Kenny said. “Ultimately, we want to develop a comprehensive small-acreage landowner system where we can show some fruit and nut trees and ways to manage all of that off the natural systems here.”

Nich Kenny, Texas AgriLife Extension Service irrigation specialist in Amarillo, shows off the new rainwater harvesting system and square-foot garden plots established for demonstration purposes at the Texas AgriLife Research and Extension Center in Amarillo. (Texas AgriLife Research photo by Kay Ledbetter)

Kenny said this project, sponsored in part by the Ogallala Aquifer Project, is aimed directly at conserving and making the best use of water – in this case it is harvested rainwater.

“We’ve got a setup where we can catch water in a large container directly off the center, which has lots of roof space and land space, and make the best use of that water coming off the roof to demonstrate to the public things we can do to be very conservation-conscious at our homes, as well as in small-acreage settings,” he said.

The rainwater harvesting system built at the center collects the water through an internal-pipe rain gutter system, Kenny said, and then it is forced back up to the top of the tanks through a gravity-flow system. The tanks are 3,600 gallons each, or collect about 3,300 gallons until overflow.

“This year in the midst of a drought, we filled three of these tanks – approximately 9,000 gallons of water – on 6 inches of rainfall,” he said. “That’s a pretty effective way to capture water.”

Nich Kenny, Texas AgriLife Extension Service irrigation specialist in Amarillo, shows how the drip tubes will distribute the harvested rainwater on the square-foot garden plots. (Texas AgriLife Research photo by Kay Ledbetter)

Kenny said with a 1-inch rainstorm, estimate that on every square foot of rooftop, approximately 0.6 gallons of water will be collected.

“You can start to add that up on a standard house and basically what you end up with is a whole lot of water that can be stored,” he said. “Next you have to figure out what to do with it.

“One thing I’ve noticed is that people involved in gardening tend to be more conservation minded,” Kenny said. “And so the strategy we took was trying to demonstrate how to use this rainwater in multiple garden settings: the square-foot gardens, larger box gardens and a traditional-size garden.

“The square-foot gardening technique is incredibly efficient in terms of water use as well as plant production, whether it be for a vegetable or ornamental garden,” he said. “We wanted to compare the other systems to this for efficiency.”

The system has drip hoses coming into the different settings, “so we can isolate where the water goes. Unlike a traditional garden, where you have water running down the furrows and maybe out of the garden or on the bare surface, you can eliminate all of that by putting the water directly where the plant can use it,” Kenny said.

A traditional garden plot will be grown along with square-foot gardens on demonstration plots designed to be watered with rainwater harvested from the Texas AgriLife Research and Extension Center in Amarillo. (Texas AgriLife Research photo by Kay Ledbetter)

Another benefit, he said, is rainwater doesn’t contain the salt or chlorine that may be in city water, and the plants respond a lot better. The water also is basically free once storage tanks and facilities are built.

To establish the square-foot gardens, he said they built a planter box that is about 6 inches deep, and is constructed from 2-by-6 inch boards in a 4-foot by 4-foot square to provide 16 square feet of garden space.

“We built the soil in there completely,” Kenny said. “It is compost, vermiculite and peat moss combined in equal proportions. That allows for a good soil structure.”

Some of the square-foot gardens are on elevated beds for people who might have a bad back or bad knees and can’t get down to garden or who might be in a wheel chair or those who want to sit while they garden. These are right at hands reach, he said.

“We also have the more inexpensive model that is a standard square-foot garden strategy built on the ground,” Kenny said. “In this case, you just put down a weed cloth and build the plot over it and fill it up and it’s the same exact premise.”

In a larger box, he said they used 2-by-12 inch boards and filled about half of the box with sand and then put the soil mixture on top of that.

“The idea there was when you have potatoes, carrots, radishes or turnips or onions or things with a rooting bulb you want to harvest, it has plenty of depth for that root to grow,” Kenny said.

“One of the reasons we filled it with sand was obviously for expense,” he said. “But the main reason is so the water can freely move out of it so you don’t wind up with saturated conditions or fungal conditions or anything that is going to cause any sort of root rot or plant damage.

“The idea is you get just enough water on to do the work the plant needs done and then you can pull the water off and manage it very efficiently.”

Kenny said all of this is a work in progress, this is the first year any of the gardens will have any plants in them.

The traditional garden plot has had manure on tilled ground for six months, and a fence is being built around it to keep the rodents out.

The ultimate goal is to compare efficiencies between the different sizes and styles of gardens, and also utilize the rainwater and see how far it can be stretched.

“I think we will see this year that we will have enough water to spare by what we’ve captured in our tanks,” Kenny said. “And hopefully the public will be able to see ways they can improve gardening at their home as well as improve their water conservation efforts.”

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