What is the Oak Creek Center for Urban Horticulture (OCCUH)?

The Oak Creek Center for Urban Horticulture is located on a 6-acre plot on Oregon State Campus, on the banks of Oak Creek, on the corner of 35^th and Western Ave.  The center serves as an excellent resource for students to learn about and become involved in sustainable horticultural practices. 

Soils surrounding the OCCUH

...what did we do there?


 Upon arriving bright and early at the center, we met up with one of the facility’s head coordinators, Cody Buckman.  Cody gave us a tour of current projects happening at Oak Creek, such as new composting facilities, cover-crop experimentation, organic vegetable gardens, green house gardening, and vertical gardens.  After touring the facility, we began harvesting a variety of peppers, composting excess vegetation, and trimming perennial bushes for over-wintering. First, we harvested poblano pepper plants and hung them in a greenhouse to dry.  In order to do so, we removed the entire plant, while leaving the roots in the soil to add organic matter. We trimmed any excess leaves or stems off of the plants to prevent the fruits from rotting. When dried, poblano peppers will become ancho chiles. Next, we planted seeds for salad greens and radishes, which will grow in the greenhouse during the winter.  We then continued to harvest over 150lbs of bell and jalapeno peppers, which will be donated to the Linn-Benton Food Share.  Overall, the day served as a learning experience about organic farming practices and soil management techniques.  This gave us a unique opportunity to see the knowledge and effort required to produce the food we often consume with little thought to it’s origin. 

OCCUH's vertical garden

What's the soil like at the OCCUH?

Soil Descriptions:

1.The Dayton Silt Loam series comprises about 58.3% of OCCUH. It is a fine, smectitic mesic vertic albaqualf, which is a deep poorly drained soil formed by silty and clayey glaciolacustrine deposits on terraces. As an alfisol, it has a Bt horizon of translocated clay accumulations. This horizon functions as a low permeability horizon, making it difficult for water to drain past this layer. Therefore, his soil series is saturated during the winter and spring. The Bt horizon is also contains iron concentrations from redox reactions resulting from aquic conditions. Dayton silt loam also has an albic (light colored) E horizon, or depletion zone, resulting from the leaching of clay and iron into the Bt horizon due to aquic conditions. This series has about 35.8% smectite clay. Smectite is a shrink/swell clay, so this soil will exhibit some shrinking and swelling due to wetting or drying.

        Dayton silt loam is classified as a farmland of statewide importance – one level below prime farmland but still relatively fertile. Its available water supply (AWS) is 7.90cm/50cmsoil. Its saturated hydraulic conductivity (Ksat) is 3.56µm/sec. The percent organic matter in this soil is 1.14%. It has a T – factor of three, meaning it can lose three tons of soil per acre per year without losing productivity. Its cation exchange capacity (CEC) is 27.9milliequivalents/100g soil. This is a relatively high CEC value, meaning there is ample potential for cation exchange in this soil.

2. The Bashaw Clay series comprises about 41.7% of OCCUH. It is a very fine, smectitic mesic xeric endoaquerts, which is a deep, poorly drained soil formed in clayey alluvium, flood plains, terraces, or alluvial fans with slow permeability.  As a vertisol, it is composed mostly of shrink/swell smectite clay, so it shrinks and swells greatly due to wetting and drying. It has a Bs horizon of translocated accumulated iron sesquioxides due to a wet, aquic moisture regime. This soil is saturated for several months of the year. The climate in which it forms is xeric, meaning it has dry summers and wet winters.

        Bashaw clay is classified as a farmland of statewide importance – one level below prime farmland but still relatively fertile. Its available water supply (AWS) is 8.4cm/50cmsoil, a little higher than the Dayton silt loam. Its saturated hydraulic conductivity (Ksat) is 0.2µm/sec. This is much lower than the Dayton silt loam, indicating a finer particle size in the Bashaw clay. The percent organic matter is 2.69%. It has a T – factor of five, meaning it can lose five tons of soil per acre per year without a loss in productivity. This value is higher than the T- factor for Dayton silt loam, indicating a lower erosion tolerance in the Dayton silt loam. Note that the Bashaw clay, the soil series with the higher erosion tolerance, flanks Oak Creek on the OCCUH property, possibly reflecting a higher rate of pedogenesis from sediments deposited by the stream.  The percent organic matter in this section is 2.69%. This series has about 61.5% clay and thus has a super high cation exchange capacity of 45.2milliequivalents/100g soil.

OCCUH's soil map. For further soil information, visit: http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx

Group members Carly and John planting salad greens

What did we learn about SOIL?

As a result of our Service Learning Project, we learned many key soil principles. One is that wetter is not always better regarding soil fertility. If a soil is completely saturated with water, there will be no oxygen available for root respiration. Also, roots can rot due to excess wetness. Many of us used to think that wet soils were the most fertile soils, alfisols and vertisols, the two soil orders represented at OCCUH, are less fertile than mollisols, which are found in drier climates.

We also learned that adding organic matter to improve fertility and aggregation only works up to a certain point. Cody discussed how adding too much organic matter makes the soil too acidic, as the soil at OCCUH is already pretty acidic to begin with due to aquic conditions.  Adding some organic matter is good, but Cody avoids adding too much so as not to create an overly acidic environment. Another way he counteracts soil acidity is by adding lime to the soil.

Additionally, soil high in clay and organic matter will be more protected from erosion than soil low in clay and organic matter. Organic matter residue on the surface of the soil creates a physical barrier between the soil and water or wind, reducing erosion. Clay and organic matter both function to create stable aggregates, the structure of which makes topsoil less prone to crusting and erosion. Clay can also dramatically increase the infiltration capacity of soil, reducing runoff. Overall as a group we learned that a lot of work goes into organic farming, because fertilizers cannot always be applied to manage the amount of nutrients within the soil. 

Hanging poblano peppers to dry in OCCUH's greenhouse

What is the broad impact of the OCCUH?

Aside from growing and harvesting a wide variety of plants and crops, the Oak Creek Center for Urban Horticulture serves as a haven for students and other community members that wish to learn about all things horticulture.  After being at the center for only a couple hours, it becomes evident that it has deeply embedded itself in the surrounding community.  Delivering vegetables to local food shares, performing research projects such as a bee pollination study, and employing a variety of green technologies.  In addition to providing valuable information to the horticulture community, the OCCUH also serves as a canvas of sorts for local artists and those interested in permaculture.  Many innovative projects have taken place at the center, such as an outdoor classroom with stumps as seats, and annual trials of many beautiful flowers.  One of the many goals of the center is to usher in a generation of students that will have learned the value of a solid hands-on horticulture education.   Organizations like the OCCUH lay the framework for a desire for fresh grown produce and reduce the need for commercial products.  The impact of the vast and readily available knowledge of the OCCUH staff is obvious, and students are extremely receptive to the positive opportunities it provides. 


For more information about the OCCUH, please see their website: http://groups.hort.oregonstate.edu/occuh

OCCUH's outdoor classroom

One of many experimental bee hives at the OCCUH

How could soil management changes improve the OCCUH?

Soil management is becoming increasingly important as the human population grows, and can always be improved to fit the purpose.  In lecture we discussed good soil management as having low bulk density, stable aggregates, and lots of macropores. Cody said that in order to make more of the soil at the OCCUH ready for gardening, more organic matter is needed. Organic matter provides plants with carbon, energy, lowers the bulk density, and helps facilitate nutrient exchange. 

The center is already has some great management practices in place, such as using cover crops to increase organic matter and reduce soil erosion.

In the main outdoor garden, there may be a need to reduce the amount of organic matter put into the soil each year in order to keep the pH at around 6.5. This pH will allow the microbes to thrive, and produce maximum nutrient availability. Other things that may help the center include taking soil samples to check pH, cation exchange capacity, bulk density, texture, and amount of organic matter.

If this were a larger operation with use of tractors, it would be recommended that they use traffic control to prevent the field from becoming compacted. Overall, the reason soil management is important is to increase crop yields in a sustainable way so the fields are productive each year.

What is the OCCUH's direct connection to soil? How does soil make this project work?

 Without good soil management practices and nutrient availability, the OCCUH simply wouldn't exist here on OSU campus.  Soil is a vital component of the OCCUH because all of their projects rely on the soil to function.  The gardens, flower beds, the health of the bees, is all reliant on the health of the soil. In order to provide nutrient-rich soil, Cody relies on several different management techniques such as adding organic matter, liming, using nitrogen-fixing cover crops, and maintaining aggregation by leaving roots in the ground over winter.  Without nutrient-rich soil, the OCCUH would have trouble producing all of it's veggies, most of which are donated via the Linn-Benton Food Share, or sold to Housing and Dining Services right here on campus. As students at OSU, we are lucky to have fresh produce available to us in our dining halls throughout campus, none of which would be here without the fertile Willamette Valley soils.

Planted Sudan Grass as a winter cover crop.

Peppers that our group harvested.

Group Members:

Kylene Thorson, Jennifer Hang, Roslyn Albee, John Bonoff, Carly Cassidy