2014-06-03 Water Conservation in a North Texas Back Yard

[Note: Figures described are not included.]


My goals are to save rainwater and greywater for trees by optimizing soil nutrients, reducing soil erosion (wind and runoff) and determining the best of three plants alone or in competition along a fence line in a north Texas residential back yard.  The process studied will provide an interactive measuring system for the home owner (or land use manager) to support plants with the least amount of intervention and most efficient use of a valuable resource, water.  In addition, I hope to determine whether the root system(s) of the chosen plants are affected by competition and how the soil nutrients are affected by different plant selection.


History: According to Stewart et al., the backyard for study is situated in the “Great Plains”, a central area of the United States extending from Canada to the southern part of Texas of clays covered by a dusty “loess”, which my dictionary [Merriam-Webster] says is a buffy to yellow loam brought here by the wind (2010). The backyard of this property was initially bare (red) dirt in 1971 when the house was built and purchased. Shortly after purchase, the owners landscaped the backyard to include a six foot high cedar plank fence and two gardening areas (vegetables and flowers) bordering the fence as indicated on Figure 1. Water: The garden areas and the fence have a concrete border approximately 30.5 cm wide with 15 cm gap under the fence for drainage as indicated in Figure 1.  A rock has been installed in this drain to prevent the rabbit(s) from coming in and eating the garden.  There are no pets in the yard, though frequent visitors of birds, domestic and feral cats, mice, possums, rats, rabbits, tree and ground squirrels, and skunks have been observed. A sprinkling system for both garden and lawn was installed in the late 1970s.  Nutrients: The homeowners used typical fertilizers early on, with only manure and natural pest repellents on the vegetables, while migrating towards more natural fertilizers in the last two decades.  No harsh chemicals have been applied to the property, with the possible exception of the fire ant treatments in the 1990s (Hollyxxxx X2 Personal Interview. April 13, 2014). Soil amendments have been made in recent decade by applying layers and patches of compost provided by the city of Wichita Falls.   Light: There are four pecan trees and one Japanese black pine in the backyard. We agreed that all the trees are 35 to 40 years old while the biggest tree is “… paper-shell pecan [s]tore bought at a nursery” (Ibid). Many varieties of grass have been sown over the years to provide for broad coverage in deep shade to bright sun under gaps in the tree canopy.  The back row of yardage, along the fence, is chosen for this study, because it has the highest degree of variation in soil composition (nutrients), elevation (the most to gain in slowing runoff), and light (full shade to full sun) (see Figure 1 below).

[Insert Figure 1 here – see Water Optimization Figure 1. pdf]

Figure 1. This is an original 1971 property survey drawing with location of proposed study planting square(s), drainage, shade, elevation and spacing trees noted.

Design: Soil Nutrients: The available nutrients such as nitrogen and potassium can differ in form, dispersal and source (e.g. organic versus inorganic)  (Craine and Dybzinski, 2013). According to Craine and Dybzinski, under the stress of competition for resources plants develop longer roots or plants may not develop longer roots(2013).  In other words, competition by plants is a complicated matter to determine in the best of conditions.  Water: In this location we are in drought conditions which are likely to continue and we are headed into the hottest part of the year. Craine and Dybzinski state that “…. competition for water is less studied than nutrients (or light) …. [and] … poorly quantified” (2013). I propose that providing a stressful environment will give the plants deeper root systems and any subsequent transplanting into the ground should improve plant survival rates.  I suspect that soil nutrients will vary in their composition at the end of the experiment. Water: Our water is often contaminated with solubles, such as roof debris and bacteria in the rain barrel water (Schiermeier, 2008) and other substances from the greywater ( e.g. coffee, rock power, seaweed, tea and vinegar).  The available water will be supplied only when required. Many hydroponic resources warned that using liquid plant food and/or volcanic rock in the soil can clog the equipment.  I could not locate any sources that have found similar effects on plants, but I choose not to use either.  Light: Competition for light is made complex by angles, direction, vegetation, wind and weather (Craine and Dybzinski, 2013).  In the case for this study, the presence of shade variations across the yard will be noted, but not detailed unless further investigation proves that there is some benefit. Measuring UV light is an expensive and time consuming process.  I choose to measure the light with the simplest and most inexpensive tool and then review this methodology when the project is operational. Soil reflective qualifications will be ignored for the purposes of this study, except those that may be part of the soil tests obtained quantifying mineral composition.  The plants will be mulched and all pots will be the same color to minimize variation and to maximize moisture retention, especially in drought conditions (FAO Corporate Document Repository, 2005). While analysis of soil spectra is interesting, the benefits of local investigation are unknown.  I choose to limit the scope of the study at this time. Plants:  Many tropical birds, such as the Slaty Finch, prefer (Chusquea) bamboo seeds. (Sanchez, 2005). In recent months, I have noticed a reduced level of bird population in the yard under study and when we experienced a recent rain, I noted that the centers of the bird deposits were mostly worms.  Better soil is maintained through the retention of earthworms (Trammel, 2014).  As my first plant, I choose a “clumping” variety of bamboo (Chusquea, if available) versus a “running” bamboo because it is less likely to get loose and grow out of control).  This plant will also prove valuable as a windbreak and have the side effect of increasing the privacy of the fencing.  As a second choice, the Egyptian (aka fern-leaf) lavender is drought tolerant and does not require fertilizer with a side effect of repelling fleas (Green, 2014). There may also be some benefit from harvesting lavender oil.  This variety of lavender, Lavandula multifida is a Zone 8 plant, but I have heard that we can push the growing zones hotter and I found a link that reports it growing in Grapevine, Texas  (http://davesgarden.com/guides/pf/go/2862/#b).  Lastly, I have wanted to experiment with switch grass since I discovered that it might be a good alternative for biofuel production (Biofuels from Switchgrass: Greener Energy Pasture). Tall grasses are also known as good windbreaks for blowing sand and dust.  Panicum virgatum L. – switchgrass, PAVI2 in the USDA database is my current choice and it is a good nectar source for butterflies (NPIN: Native Plant Database, 2014). Timing: This study will be conducted this summer starting in June through August, with preparation in May.  Each month will be a phase with some unique activities in each.

While the purpose of the study is to provide more water for the trees, I hope to answer other questions.  Do plants in similar environments develop better root systems alone or in competition?  Do the recommended soil amendments vary across the back of the yard? Measuring and meeting the watering needs of similar plants in similar soils should provide results indicating the benefits of shade and the range of water usage. I hope that the benefits of knowing which plants grow best in different locations using the least amount of water should prove valuable information.  In addition, I hope to optimize soil nutrient and utilize water more efficiently in the future.

Material and Methods:

Layout:  The backyard will be gridded with landscaping spray paint in square yards as indicated in Figure 1.  Inside each of the 21 square yards, 1 square yard each, will be four identically sized pots, three different plants individually and one pot with all three plants.  I plan to use fiberglass insulated pots to minimize temperature changes at the root level since they cannot be adequately controlled or measured in the ground. Note that budgeting for this project includes the proposal of fiberglass insulating pots which are expensive and could be made from other materials.  In the interest of time and uniformity, I plan to use a wholesaler. Soil amendments will be made based on the soil tests (calcium, magnesium, nitrogen, pH, phosphorus, potassium, salt, sodium and sulfur) provided by the Texas A&M AgriLife Extension Service (Trammel, 2014). Mulching will be placed over, between and on the ground to reduce evaporation. A bed of medium size rocks and the rock blocking the drainage channel in the concrete will be kept in place to support the pots for drainage and to prevent rapid water movement in the event of the runoff. Insulated pots will be kept above ground until phase 3 to prevent flooding. Bamboo (tallest and broadest leaf plant) will be located at the back, nearest the fence in each square yard.  Switch grass will be located in the middle and lavender placed in the front to minimize foliage blockage of available light.

Measurement: In addition to the preparation phase, the soil test(s) will be repeated at the end of the experiment to determine how soil nutrients vary among the plantings.  One method of estimating soil moisture is to use a long screw driver (18 inches) and measure the ease with which you can push it into the ground (McGraf D Rainwater Harvesting, Arts Alive! Home and Garden Festival. February 22, 2014).  This method will not provide the real time raw data desired for the purposes of this study. A moisture measuring device will be included in each square bed in each pot (84) (refer to the budget, Table 1). The plants will be purchased at approximately the same time and as close to the same size as possible.  In addition, plant height and width will be measured every 72 hours. Root ball will be measured at the end of the experiment, before planting acceptable plants in the ground (see the wrap-up phase in the timeline, Table 2 on the last page of this proposal).

Process:  In the preparation phase, the wireless monitoring device [Koubachi K002 Outdoor Wi-Fi Plant Sensor] will be tested, materials ordered, and seedlings gathered.   I propose to provide one wireless monitoring device in each of the experimental plant pots to maximize the information obtained from this study. This wireless device will allow much faster and improved data collection for each individual plant, including light, temperature and water.  I will take photographs of the plants at least weekly. In phase 1, the plants will be planted. In phase 2, plant monitoring will be reduced to “surviving” plants to minimize water usage.  In phase 3, plant roots will be measured and optimum plants either planted in the ground, or pots depending upon the degree of root ball growth.  During the wrap up, the soil nutrients will again be tested and the excess monitoring devices(and other materials) donated to educational organizations.  The data statistical analysis will be determined by the results during the wrap up phase.

Current Progress:

I am investigating other ways to measure and monitor the backyard using online do-it-yourself guides.  One resource looks promising.  I also am investigating alternatives to insulated pots (e.g. making your own using bait buckets) and comparing their performance to the few I already own. This effort is an attempt to reduce the budget so that the maximum level of wireless monitoring can be maintained.

Literature Cited:

“Biofuels from Switchgrass: Greener Energy Pasture,” https://bioenergy.ornl.gov/papers/misc/switgrs.html

Craine JM, Dybzinski R (2013) Mechanisms of plant competition for nutrients, water and light. Functional Ecology 27: 833-840

FAO Corporate Document Repository (2005) Synthesis report of the FAO electronic conference “Drought-resistant soils: Optimization of soil moisture for sustainable plant production,” http://www.fao.org/docrep/009/a0072e/a0072e05.htm#TopOfPage

Green K (2014) Plantiful: Start Small, Grow Big with 150 Plants That Spread, Self-Sow, and Overwinter, Timber Press, Portland, OR

NPIN: NATIVE PLANT DATABASE, Lady Bird Johnson Wildflower center, the University of Texas at Austin, http://www.wildflower.org/plants/result.php?id_plant=PAVI2

Rolling Plains Master Naturalists, http://txmn.org/rollingplains/

Sanchez C (2005) First Description of the Nest and Eggs of the Slaty Finch (Haplospiza rustica) and Observations on Song and Breeding Behavior.  Ornitologia Neotropical 16: 493–501

Schiermeier Q (2008) ‘Rain-making’ bacteria found around the world. Nature news, http://www.nature.com/news/2008/080228/full/news.2008.632.html

Stewart BA, Baumhardt RL, Evett SR (2010) Major Advances of Soil and Water Conservation in the U.S. Southern Great Plains. In T. Zobeck , W Schillinger, eds, Soil and Water Conservation Advances in the United States, SSSA Special Publication 60, Soil Science Society of America, Inc., Madison, pp 103-129

Texas A&M AgriLife Extension, Rainwater Harvesting http://rainwaterharvesting.tamu.edu/

Trammell B, Wichita County Master Gardener(s), February 15, 2014. ‘Good Soil’ an important part of the equation for healthy, productive plants. Times Record News, Wichita Falls, Texas


The following Table 1. provides a line item accounting for known materials needed for this project.  However, there are some items of measurements, such as homemade sensors, that work on cell phones (Android) and simple measuring tools (e.g. for leveling purposes) that are not expected to be purchased, but instead used in other projects.

Table 1. Water optimization project budget with extended costing, comments and source(s) noted.

[Insert Table 1 here – see Water Optimization Budget Planning.pdf ]

Time Table:

The preparation phase on this project will likely be the most labor intensive part of the study.  While I believe the time table is doable, I will include some preparations for weather (storms, extreme wind) and support for measuring methodologies that are not detailed in the time line.  A detailed log will be kept of all project activities and delays explained when and if necessary.  Significant weather will be recorded in the log. The calendar months have been used for phases, but phase labels should be used in any referencing so scheduling delays will not impact documentation. The timeline is presented in the following Table 2.

Table 2. Water optimization project timeline table with project summary descriptions.

Description: Short Name: Time Expected:

Testing, Preparation, Planting Prep Phase Month of May 2014

Plants Monitoring Phase 1 Month of June 2014

Surviving Plants Monitored Phase 2 Month of July 2014

Roots Measured, Chosen Plants Situated Phase 3 Month of August 2014

Organize results and discussion Wrap Up Phase Sep-Oct 2014

Production Milestone target Final Phase November 2014

Presentation Presentation Phase December 2014

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