Rhizosphere Ecology in Changing Cropping Systems

Final Report for EW05-006

Project Type: Professional Development Program
Funds awarded in 2005: $7,348.00
Projected End Date: 12/31/2006
Matching Non-Federal Funds: $3,800.00
Region: Western
State: Oregon
Principal Investigator:
Sandy Macnab
Oregon State University Extension, Sherman County
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Project Information


Priority was to schedule a workshop emphasizing the actual soil impacts on quality factors related to various tillage practices. This included an indoor classroom seminar followed by a day of site visits to soil pits which would reveal impacts of recent use.
Dr Jill Clapperton of Lethbridge, Alberta, Canada was key speaker. She was used to participate at the seminar and then field sites in five counties over four days.

Project Objectives:

Primary objectives were to present this information to key audiences: the regulatory and advisory agency personnel and the producers who must make the decision to employ a given practice.

The opening day program brought in three state-wide researchers, seven county ag agents from two states and 13 representatives from local, regional and state offices of USDA and SWCD's. Another two Extension Agents were involved in the field site visits. Sixty eight growers representing nine counties and two states were records as attending the session as well. A total of 97 attended the opening session.

County agents involved in the process, contributed time and funds to the program, setting up pit sites in cooperator's fields, advertising/promoting in their area, providing soil samples for soil testing before the program and proving site samples for growing plants to show variances in soil health by different management practices.

NRCS and SWCD reps were an important component of the audience as many have been under pressure to push a politically correct agenda that does not always pass the test and needs of sustainability.
The workshop was to help bridge the gap between perceived and reality for both advisory and producing sides.


Growers in this low rainfall (9-13.5 inches MAP), traditional dryland producing region have historically produced soft white winter wheat, in fact the five county region produces 75% of Oregon's wheat. Growers know that crop and tillage rotations offer a break in disease and weed cycles, and many new for the area crops are tested regularly. Many of the changes take time for the benefits of the changes to take place and there may be other advantages in decreasing inputs costs to help make the other "newer" crops more economical and sustainable.

Dr Clapperton is one of the leading rhizosphere scientists anywhere, conducting research at her experiment station in Lethbridge, Alberta and utilizing these methods on her family's private farm in the area. Her particular interest is how tillage and cropping rotations impact the soil quality, health and productivity.

We invited Clapperton to address the issues and her experience to local producers over the five county region followed up by actual field visits to pits dug 4.5 to 9 feet deep, where she would analyze the soil structure and health, pointing out particular, signature signs of the management systems used in the area. In the last three counties she presented a short classroom update before proceeding to the soil pits as many of these folks were unable to attend the opening workshop discussions held in The Dalles, Oregon at the Discovery Center. She spent day two touring soil pits in Wasco and Sherman Counties, where most of the producers had attended the open day program.

Education & Outreach Initiatives



Activities and Methods -- Because of the joint effort in this promotion, reps from each county will have to work closely together to identify and secure cooperators and sites. The core group of service personnel has already met and planned the activities. Extension agents across the plateau will further meet to discuss and plan the need for handouts and other learning materials and the possible scholarship activities to promote this idea to peers across the nation and to develop and conduct evaluations.
The first day seminar will serve as training session for these service personnel and
they then proceed to assist present with Clapperton at their home sites during the field workshops.

By combining both the indoor and the outdoor sessions, the program is designed to service a variety of learning styles.

In addition, an ARS team participated at each pit site over the week conducting soil moisture infiltration rates. Although only done once at each site and not replicated, they still provided a degree of consistency and numbers that producers could understand and relate to. This was especially important because local growers understood the practices in their area, the expected yields in their area, and could understand that water that moves into the soil does not contribute to erosion issues. The majority of site pits were located in ground designated at "Highly Erodible".

Outreach and Publications

No publications were planned to come from the workshop. Follow up reviews were planned using photos from the programs, but when the camera of the official designated photographer went on the fritz, two roles of film and a series of once-in-a-life-time photo opportunities were lost.

Information summarizing the discussions and water infiltration differences were publicized in the Mid-Columbia Farmer's Newsletter, an Extension publication that reaches about 560 ten times per year. One regional newspaper included a picture of the activities at a soil pit in a county on the east edge of our targeted market.

Outcomes and impacts:

Outcomes: The agency personnel, by participating in both the seminar and the field workshops, will have a much clearer understanding of the soil changes that take place under different cropping system practices and be more able to communicate the implications of sustainability to others, especially farmers who have not adopted the newer techniques. Producers attending the field workshops will gain visual understanding of the complexities within the rhizosphere and re-evaluate their own practices. Growers will be more willing to conduct their own trials and be better able to judge the benefits in something other than yield. Agency personnel and producers alike will gain in understanding on how decisions impact the long-term sustainability of their environment.

Project Outcomes

Project outcomes:
Practice Changes

Extension program do not seek to promote change per se. The objective is to provide enough information in an understandable format so that persons can make informed decisions. Changes must be made on a voluntary basis not a mandated one if they are to succeed.

But we did have changes. Water infiltration rates were taken at each pit site and although these were once-only tests, they did provide a wide range of infiltration numbers. This proved to be another eye-opener for both producers and technical advisors. One no-till annual crop site was tested at 7 inches per hour of infiltration an excellent number for reductions in soil erosion, while a newer no-till/annual crop site rated at only .38 inches per hour and was the absolute driest spot visited. This created an interesting discussion of why the big difference.

The obvious answer is that the first field was converted 16 years earlier, before the drought, and was in good enough shape to handle the extended drought when it hit. The later one, converted only 6 years earlier, was struggling seriously due to the drought impact. The message was not to make major changes in practices under extreme negative conditions.

There were memorable moments. On field that was continued to be discussed long afterwards was the field that had been bottom plowed for many years. Not only was the amount of accumulated layers of runoff visible in sediment layers, but there was also a layer or ash that remained from a fire everybody remembered as three years earlier. It was amazing that this layer impacted root penetration and how much sediment had accumulated above it. This was one of four sites with a half mile strip. Infiltration rates ranged from 7 inches on the no-till annual crop to 3/16 of an inch on the plowed ground. On a field recently converted from stubble mulching to chem-fallowed cropping system the rate was 1.5 inches per hour and near-by site under some trees, the rate was at 2.2 inches but the soil surface there was impacted by livestock use.

In Sherman County, the two sites closest (within a half mile) to the young annual cropped site included a recently converted chem fallowed site and an old barnyard site that has not been farmed not r impacted by livestock in over fifty years. The water infiltration rate on the old barn site was at 4.5 inches while the chem fallowed field site was at 9/16 of an inch, still over twice the annual cropped site. Back on the Sherman Station, a stubble mulched crop site tested at 3/4 of an inch while the grassland strip fifty feet away tested at 7.5 inches. The message was emphasized that tillage impacts soil condition, a message that was clearly visible.

The overall rating for the program was a 4.8/5.0.

The workshop participants agreed strongly that enough information was provided. They did consider many changes: 44% considered changes in their tillage practices, but only 37% actually employed a change. Two thirds considered a change in crop rotations but 71% actually made a change, partially inspired by the continued drought and the disease issues that were associated from not using a “break crop” one that grows differently than cereals and expresses different pressures on weeds and disease. Two thirds indicated they considered a different crop in the rotation but only a quarter of the respondents actually did some kind of change and those were away from the changes proposed by Clapperton. The lack of moisture and lack of economic support for these alternative crop selections played an important role according to the respondents.

There was a measured change in chemical application practices where almost two thirds admitted making a change here, partially driven by economic reasons once again.


Potential Contributions


The key points that were clearly demonstrated were that one does not want to make drastic changes (nor evaluate them) in productions systems during a period of extreme weather conditions. The drought definitely soured some people on making changes because the results during the drought were disastrous

A second key point is that sustainability must include economics with ecological and environmental factors. Sometimes that is a difficult concept for those who deal strictly with the last two factors.

And finally, the workshop generated a deal of serious discussion about whether we should be seeking to find an alternative crop or letting other areas struggle with that issue while we concentrate on our natural competitive an comparative advantages of producing high quality, low protein soft white wheat on a minimum of rainfall. And if so, how do we best protect the resources against erosion.

Future Recommendations

Considerations to Consider

The program had many supporters and many sources contributing to the funding that made it possible to get the speaker here (altho there are some interesting stories about renting a car in Canada and paying with US dollars).

Several counties were involved in hosting Clapperton and she stayed with growers active in the PNW Direct Seed Association, which helped contain some costs.

However, there needs to be a better way to involve more people from the start of the proposed project in order to give them opportunity to contribute more to the program and be more understanding of the purpose of the program. In some cases, soil pits were dug where a backhoe could be found rather than in an area where a particular point might have been more clearly demonstrated. Back hoes proved to be an expensive part of the program and had to be used before and after the visit. Cooperators were terrific about allowing us to dig said pits on their land and with little restriction.

While the use of soil pits was critical, some of the pits posed a potential hazard and even with safety barriers around the pits, there may be question as to whether or not they were adequately safe. A pit collapse could have been deadly in several of the deeper pits, even though they did make great show cases for discussion purposes.

Tying the program across five counties was a huge effort, meaning communication needed to be clear and frequent. Counties were not given much chance to buy in or not, which was a mistake. If an individual did not want to participate, they needed to be given more of an opportunity to suggest a replacement. Too many decisions were made at one end of the spectrum and others not given much chance to input into the program other that being told what they needed to do.

Agency cooperation was invaluable and altho already good across the region, resulted in being made stronger. Cooperative efforts like this have value.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.