Rhizosphere Ecology in Changing Cropping Systems

2005 Annual 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

Rhizosphere Ecology in Changing Cropping Systems


Summary: Soil Rhizosphere Ecology in Changing Cropping Systems

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, Ontario Canada was key speaker. She was used to participate at the seminar and then field sites in five counties over four days.

Objectives/Performance Targets

Provide better information to educational (Extension), advisory (SWCD)and regulatory (NRCS) personnel in the dry land, low-rainfall (9-13.5 inches MAP), winter precipitation cereal producing region of North Central to North-Easterly Oregon. Better background would help dictate how processes could work to improve various best management practices and what realistic barriers still exist within those systems.

Active producers and landlords were another primary target as suggestions for change in practices to growers are only advisory, the actual producers must be able to see and understand the actual impacts themselves in order for them to make informed decisions regarding their choices, choices that would impact production, economic and resources management. The key was to get producers to understand the consequences of their decisions to change or not.


Because the workshop included a day in seminar and a day in the field at actual soil pits in different production regimes, samples from these pits were taken earlier and submitted for soil sample testing and a onion plant was planted in each soil providing a visual indicator of various limitations and strengths of each. This was primarily for those who would not attend the second day site visits and for our visiting scientist to gain a better understanding of what she might expect before we visited these sites.

The seminar received a 4.1 rating (on a 5.0 scale)but the actual field site visits rated 4.8 as far as effectiveness in communicating the impact the various practices had on the soil at all levels. Soil pits ranged from a minimum of 4.5 feet to 9 feet deep, presenting clear views of depth of root penetration and the depth of existing wormholes, and various limiting factors as well as remnants of past soil activities. Very impressive.

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 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 abosulte driest spot visited. This created an interesting discussion of why the big difference.

The obvious answer is that the first field was convereted 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 remebered 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 nor impacted by livestock in over fifty years. The water infiltration rates 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. No one from the Wasco and Sherman County regions attended the programs in Gilliam, Morrow and Umatilla Counties over the next three days as these were handled by the Extension agents in those areas. The ARS staff continued to make water infiltration tests at each site, but no data is available.

There are also no pictures from the first two days of the event as the camera designated as the official photographer went belly up and could not be replaced in time to recapture the scenes.

Impacts and Contributions/Outcomes

Extension workshops are presented to provide information, enough so that the individual has enough information upon which to make a decision regarding change of practices. We do not promote change per se.

The workshop participants agreed strongly that enough information was provided. They did consider many changes: While 44% considered changes in their tillage practices, 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.

One of the factors most cited for motivating a change in practices was the Conservation Security Program, a USDA program that rewards growers for the good conservation practices they already employ with an incentive for them to select which others they will adopt. While the CSP is only available in limited areas (one watershed out of the three in the Mid-Columbia Region) this volunteer program received more favorable remarks for change than any other positive incentive. On the flip side, receiving the same number of comments as a dis-incentive was the lack of marketing opportunities for the non-traditional crops. A lot of crops can be produced in the area, but if there is no economic support, they won’t be produced.

One respondent further expressed that Clapperton’s growing region was significantly different from ours and he felt her comments were impractical for here, although he did not attend the field soil pits visits the next day. On the opposite side, one particular orchardist began planning to bring Clapperton back for the orchardist’s annual educational meetings, believing that with their irrigation and such, her remarks would have greater consequence for that industry in the region.

Planned purchases of soil infiltration and soil penetrometer equipment were not made as NRCS made their existing sets available to interested persons, so there was no need to duplicate equipment purchases.

There were no publications generated from the workshop altho information was used in subsequent discussions with growers. Some results were shared via the Extension newsletter.

The workshop achieved its goal of providing information upon which to make a decision and several changes in practices were adopted. However, factors attributed to the extended drought and the lack of markets for alternative crops may have more to do with those changes than the actual workshop.