Final Report for SW01-061
In collaboration with farmers, we investigated the integration of four practices: winter cover crops, reduced tillage, pesticide refuges, and integrated pest management. The results showed that cover cropping had the biggest impact on improving soil quality, which promoted earthworms (even in tilled soils) and other soil biological and physical properties. Although strip tillage stimulated soil biological properties, there was a concurrent decrease in soil physical properties, which caused an increase in compaction. This resulted in decreased yields for snap beans, but broccoli and sweet corn were unaffected. Extension activities using the soil quality kit have been done. Reduced tillage seemed to promote the reduction of pesticide use but we had evidence that slugs and symphylans may be more problematic in these systems.
1. To fully integrate farmer/scientist contributions to research, evaluation, and dissemination of findings related to the use of cover crops, reduced tillage, establishment of tillage and pesticide refuges, and the use of more integrated pest management tactics on vegetable production farms.
2. To establish a network of on-farm research and demonstration sites where large-scale, long-term studies compare conventional and integrated vegetable production systems.
3. To track changes and validate the utility of soil and biological indicators of agroecosystem integrity we have identified in our past research efforts.
4. Disseminate findings to promote integrated vegetable systems to farmers and agricultural professionals.
There are increasing demands for processed vegetable growers in the Pacific Northwest to reduce pesticide applications, improve salmon habitat, and enhance soil quality. Because vegetables are a high value crop, any decreases in yields or setbacks in fruit maturity or quality can have significant negative economic impacts. Therefore, growers are interested in a system that provides a balance between addressing environmental concerns and maintaining high quality/low risk production. A production system that integrates reduced tillage and cover crops has the potential to meet these needs. Reduced tillage, in combination with cover crops, can improve the quality of soils, decrease erosion, and optimize crop productivity. The improved soil quality can affect crops by providing a superior rooting environment, increasing water infiltration and storage, and promoting beneficial microbial and faunal communities that decrease pests and diseases.
Despite the advantages of cover crops and reduced tillage, vegetable growers have had mixed results with integrating cover crops and reduced tillage. It seems likely the soil response may be related to these management effects on crop productivity. Understanding the soil biological and physical mechanisms would be fundamental for guiding the development of integrated cropping systems.
There is considerable interest and some progress in developing soil quality indicators for diagnosing soil problems and to guide sustainable crop management (Doran et al., 1994; Doran and Jones, 1996; Bandick and Dick, 1999; Ndaiye et al., 2000). Limited information is available regarding soil quality and biological dynamics among trophic levels in agroecosystems (Anderson, 1988; Coleman and Hendrix, 1988; Shaw and Pawluk, 1986), particularly cover crop systems and reduced tillage. Cover crops would be expected to stimulate soil biological activity, which in turn causes aggregation of soil; reduced tillage will better preserve larger aggregates. A well-aggregated soil is important for sufficient pore space (gas exchange, water relations), root growth, biological habitat, and crop yield. Decomposing plant debris accelerates formation of persistent microaggregates (Oades, 1993). Fungi, bacteria, and worms secrete polysaccharides that induce clays to bind (Dorioz et al., 1993) and fungi to further enmesh clay particles with hyphae (Gupta and Germida, 1988). Soil fauna activity also can promote aggregation and soil structure through development of biopores, earthworm casts, and fecal pellets (25 um to 2.5 mm dia.; Moldenke et al., 1994; Oades, 1993). Although a limited amount of work (mostly in Europe, Africa, and U.S. Midwest) shows that earthworms improve soil structure (see review of Edwards and Shipitalo, 1998), there are few holistic studies that include soil microbiology, and prior to this project there was limited information in the Pacific Northwest on the role and management of earthworms.
The goal of the project was to promote the adoption of more integrated vegetable cropping systems in Oregon’s Willamette Valley. The project investigated integration of four practices at both on-farm and station sites: the use of winter cover crops, reduced-tillage planting systems, pesticide refuges, and integrated pest management to conserve natural resources and reduce pesticide applications. A holistic study of soil biology (with particular emphasis on earthworms), beneficial insects, and soil quality was conducted. This included experiment station and lab research in conjunction with on-farm and participatory research.
On-Farm and Participatory Research
Farm-scale research was conducted on 5 family-owned vegetable farms that range in size from 400 to 2,000 acres. Each cooperating farmer chose two fields that are similar or split one large field with a tillage or cover crop split a standard cropping system (no winter cover crop, aggressive tillage and prophylactic insecticide applications) and a farmer-designed integrated system (winter cover crops or reduced till planting). The target crops were sweet corn, snap beans, and cole crops grown for processing. Each farm serves as a block in a randomized complete block design. At each participating farm, two 150 X 50 ft. plots were measured to establish a cover crop and fallow split-plot field design.
Selected tests from the soil quality test kit (USDA, ARS, NRCS, SQI kit) were performed each year at the on-farm sites. These include aggregate stability, soil slaking, infiltration, and soil respiration tests. The soil quality test kit and Soil Scorecard were also demonstrated in the field to growers involved in a short course at Chemeketa Community College. The kit and card proved to be an excellent teaching tool to create “learning moments” about soils and managing soil to improve soil quality.
Experiment Station Research
The experiment is a statistically valid (4 reps) design with the following three treatments: (1) strip-till vegetable planting with winter cover crop; (2) conventionally tilled and planted vegetable with cover crop; and (3) conventionally tilled and planted vegetable with winter clean fallow. The cover cropped treatments, a combination of oats and vetch, were planted in the fall of 2001 then killed with systemic herbicide the following spring (2002). Cover crops were subsequently flailed and incorporated by disk in the conventionally tilled treatments and remained as flailed surface residue in the strip-tilled treatments.
Baseline soil samples were collected prior to treatment implementation, followed by a second seasonal soil sampling in 2002 and 2003, and a fourth soil sampling in 2004 in the spring (prior to cover crop incorporation), approximately 30 days after the sweet corn was planted and at harvest. Soil cores were collected to a depth of 10 cm, with a separation of 0-5 and 5-10 cm cores in the strip-tilled plots. Approximately 15 cores were sampled (both interrow and intrarow) and pooled in three different locations within each plot. All soil collected was passed through a 2 mm sieve and a portion was retained at field moist conditions to measure microbial biomass. The remaining sieved soil was air-dried and stored at 4oC. Baseline measurements of total C and N, texture, and pH were done prior to initiation of the study. The soil quality measurements we will run at all sites include bulk density (Troxler density gauge -– our previous experience with core method was unsatisfactory and not reproducible), pore space static penetrometer (Dickey-John penetrometer), dry aggregate distribution (1-2 mm fraction has been sensitive in detecting treatment effects), pH, microbial biomass C/N (fumigation method), C-mineralization (10 d lab incubation), B-glucosidase activity, and springtail and earthworm counts.
ON-FARM RESEARCH AND EXTENSION
The goal of this part of the project was to promote, in collaboration with farmers, adoption of more integrated vegetable cropping systems in Oregon’s Willamette Valley. The approach involved a series of meetings and ultimately implementing on-farm research and demonstration activities.
Results from the soil quality test kit’s soil respiration and infiltration (12-inch falling head infiltration ring) tests did not indicate differences between treatments and showed high variability in the results the first year after field treatments were applied. However, after 3 years of treatments, infiltration was significantly higher with cover cropping in farmers’ fields. Soil aggregate stability and soil slaking preliminarily show a trend toward increased soil stability in reduced-tillage systems, with soil slake test results pointing toward significant differences between tillage treatments. This is encouraging as a potential monitoring tool for growers to assess the success of their management practices since the soil quality test kit is easily available for their use. These data also show potential for using these selected tests as a demonstrative tool during field days and for general presentation of the soil quality test kit. Soil respiration was not proven to be a sensitive indicator of soil health between treatments.
INTEGRATED PEST MANAGEMENT
One of the goals of our long-term soil quality project was to reduce crop damage by insect pests with reduced tillage. A large body of scientific literature and our own past studies have shown that reduced-tillage planting systems conserve and enhance natural enemies of crop pests. Specifically, ground beetles (Coleoptera: Carabidae) and spiders are conserved in reduced-tillage planting systems. We were not successful. Although insect pest pressure varied from time to time during the growing season and from year to year, the variations in insect pest pressure did not correlate with our tillage treatments. This was true for both the small-plot research station trial and on the eight cooperating farms. In several cases, grower-managed large-plot comparisons of tillage systems produced the same results. Variation in tillage system did not correlate with crop damage by insect pests. We did, however, learn some important and unexpected lessons that could result in reduced pesticide use in the near future.
We observed that certain insect pest populations vary by an order of magnitude from one year to the next. We found that specific insect pests have consistent “low ebb” in their population which is related to their life history. This variation can be detected on a regional basis and communicated to area growers. We are confident that growers could reduce pesticide applications by 10-20% in specific crops (corn and beans) with advanced notice of reduced pest pressure. This was an unexpected finding unrelated to tillage systems or natural enemy conservation.
During the three years of the study, we grew broccoli (2002), snap beans (2003), and sweet corn (2004). Each year we established pest monitoring stations at the experiment station and on eight cooperating farms. The pest monitoring stations were made up of wire mesh, paper wing, and yellow sticky traps designed to attract broccoli, snap bean, and sweet corn pests (see below). Three tillage systems were maintained on the research station for the entire period. During the 2002 and 2004 growing seasons we compared treated and untreated sweet corn grown on farms in either a conventional or strip tillage planting systems in large-plot trials established and managed by cooperating farmers. During 2003 we compared bug bite damage to snap beans in three tillage systems at the experiment station. In 2004, we compared insect damage during sweet corn establishment at the research station in the three tillage and planting systems.
Broccoli Insect Results 2002
In Oregon’s Willamette Valley, there are four Lepidoptera insect pests that contaminate broccoli harvested for processing, cabbage looper (Trichoplusia ni), diamondback moth (Plutella xylostella), cabbage white butterfly (Pieris rapae), and, occasionally, Bertha armyworm (Mamestra configurata) as well as the cabbage aphid (Brevicorynae brassicae).The main contaminant is cabbage looper. Late instars and pupa of these insects contaminate broccoli and can result in tens of thousands of dollars of losses when processors reject truck loads of harvested broccoli due to contamination.
During the 2001 growing season, however, just prior to the establishment of our long-term soil quality study, the Willamette Valley experienced a looper outbreak. Looper pressure was very low. There were no detectable differences between looper contamination rates in broccoli growing in the three tillage treatments at the experiment station. However, the dramatic swing in looper pressure from 2001 to 2002 suggests that regional monitoring of pest population trends should continue. During outbreak years, broccoli growers will want to make adjustments in their insecticide programs over time. It is unlikely that all members of this broccoli pest complex will be low at the same time.
Snap Bean Insect Results 2003
Unlike broccoli, in snap beans there is only one key insect pest, 12 spot beetles. These insects chew on the developing pin beans causing them to deform. If bug bite is very bad, processors will reject loads of harvest snap beans. This costs farmers tens of thousands of dollars. In a survey of Willamette Valley bean growers (McGrath and Kogan, 1996), the majority of respondents (88%) listed 12 spot beetle (Diabrotica undecimpunctata) as their most important insect problem; over 70% of the 22,000 acres of snap beans in the Willamette River basin were sprayed at least once with a broad spectrum insecticide.
Beetle pressure in 2003 was normal (Figure Two ~ 12 Spot Beetle Pressure 2003). The bean crop at the long-term study site was planted according to the dictates of soil moisture. Unfortunately, this resulted in the beans blossoming and pin beans forming at the same time that the first summer generation of beetles emerged from pupa in the soil (Figure Three ~ Beetle Densities During Bean Blooming). As a result, beetle damage at the research station was severe and exceeded processor standards (Figure Four ~ Beetle Damage to Beans 2003). Bug bite was lowest in the conventional system with aggressive tillage, no winter cover crop, and little crop residue on the soil surface. Bug bite was severe regardless of the tillage system. However, we learned a useful lesson.
When we take a close look at the life cycle of the 12 spot beetle (Figure Two), we can see that there is a low ebb in above the ground adult beetle population. This low ebb occurs after the beetles from the fall generation have emerged from their winter refuges, lay their eggs, and die off. It occurs prior to the emergence of the first summer generation in July. There may be opportunities to reduce insecticide applications in snap beans during this blossoming period in some years and in some growing areas. When we detect the low ebb in the beetle life cycle, we could signal growers and agricultural professionals to intensify their site-specific field scouting. The incentive to scout fields would be the high probability of a no-spray decision based on the regional population trend. We will pursue this idea in future experiments.
Sweet Corn Insect Results 2002 and 2004
There are four soil-borne insect pests that have a significant negative impact on sweet corn establishment: seed corn maggot (Delia platura), Symphylans (Scutigerella immaculate), black cutworm (Agrotis ipsilon) and 12 spot beetle larvae (Diabrotica undecimpunctata). These four pest populations vary a great deal from year to year and from field to field. Changes in seed corn maggot populations are difficult to detect. As a result, most sweet corn seed is treated with insecticide to control this seed pest.
Symphylans are a chronic pest associated with certain soil types and crop rotations. Tillage is known to have a depressing effect on symphlan density. We did observe increased symphylan damage on some of the experiment station plots that were kept in reduced-tillage planting systems for several years. Most growers are aware of which of their fields have a history of symphylan problems and treat these fields prior to or at planting.
Outbreaks of black cutworm can cause severe damage to corn, but the outbreaks only occur about every ten years. Damage to sweet corn plantings from 12 spot beetle larvae is rare. It is only a problem when over-wintering beetle populations are high during the planting period between mid April and mid May.
During the 2002 growing season, black cutworm and 12 spot beetle monitoring stations were established on the Horning, Kenagy, Pearmine, Dickman, and Hendricks farms as well as the vegetable experiment station where the long-term tillage and cover crop comparison was in place. Compared to the seven-year average, 2002 was a normal year in terms of black cutworm pressure. Compared to the four-year Willamette Valley average, the 12 spot beetle population was normal overall and below average during the sweet corn planting periods. In five large-plot farmer managed trials on the Kenagy and Hendricks farms (Table One), there was no detectible damage to corn seed by seed corn maggot, nor damage to corn seedlings by symphylan, cutworm or 12 spot beetle larvae. Corn seedling stand counts were similar regardless of whether they were treated with insecticide. Tillage system had no detectable effect on stand count. The experiment was repeated on farms in 2004. Again, there were no detectable differences in stand counts in corn treated with insecticide or not. Again, there were no detectable difference in stand count associated with tillage systems.
Although we could not show a tillage effect on insect damage in broccoli, snap beans, or sweet corn, there still appear to be opportunities to reduce pesticide use in some years and in some fields on these crops. With careful field choice, avoiding fields with a history of symphylan problems, insecticide treatment of sweet corn seed may be sufficient for sweet corn stand establishment in non outbreak years. Reduced-tillage planting systems improve certain characteristics of soil quality without significantly increasing insect pest pressure in most cases. Slug and symphylan enhancement, however, in reduced-tillage, high-residue systems needs further evaluation. The primary factors that govern fluctuations in pest populations need further evaluation. It does not appear from these limited results that tillage is a significant factor on these crop-pest combinations.
INTEGRATED TILLAGE/COVER CROP SYSTEMS AND SOIL QUALITY
The goal of this part of the project was to address component research questions raised by vegetable producers to complement the on-farm activities. This research was done under the controlled environment of the research station toward the development of practical and credible integrated management systems to reduce external inputs and improve soil quality. Producers report that reduced-till vegetables (strip till planting) have given mixed results in terms of yields. We hypothesized that for western Oregon and its soils, strip till affects the soil biology and physical properties in some manner that ultimately is controlling crop productivity. In addition, we wanted to investigate whether earthworms could function as “soil engineers” in improving soil quality of strip-till-planted soils in systems that included winter cover crops.
Microbial biomass carbon (MBC) fluctuated seasonally for all sampling years and treatments except the strip-tilled plots during 2003. Spring sampling MBC was consistently higher than summer sampling. This can be attributed to root exudates present in the soil in spring as plant growth and turnover increase due to cover crop biomass. Tillage occurring after sampling may contribute to microbial habitat disruption. Following the first year of integration, MBC in the strip-tilled, cover crop plots significantly exceeded that of both conventionally tilled plots (p < 0.05); this trend continues throughout the remaining year of the study ?-glucosidase enzyme activity levels mirror trends seen in microbial biomass carbon data reported above. Following the first year of implementation, the completely integrated plots (strip till, cover crop) reveal increased levels of enzymes when compared to both conventionally tilled plots. Earthworm midden abundance had a similar pattern, which was especially evident during the 2004 sampling strip-tilled plots showed a steady increase in ?-glucosidase activity over the 3 years regardless of season. This contrasts with MBC, which, although showing treatment effects, showed much greater seasonal variability. Thus, as a soil quality indicator ?-glucosidase is proving to be a reliable assay that shows soil management trajectory with low levels of seasonal variability.
Both tillage and cover cropping had an effect on earthworm abundance as determined by middens and earthworm extraction. In 2003 there was no significant difference between strip till/cover crop and conventional till/cover crop but both of these were significantly greater in earthworm abundance than the conventional tillage/winter fallow. A similar relationship was found for 2004 except the strip till/cover crop was now significantly greater than conventional tillage/cover crop which, was significantly greater than the conventional tillage/winter fallow.
Earthworms require adequate food supplies as well as a relatively stable habitat. Winter cover crops provide food for anecic type earthworms, such as Lumbricus terrestris, which pull organic material from the surface into their burrows to feed. In tandem with cover cropping, reduced tillage enables earthworm burrows to remain undisturbed in a large portion of the field, thus increasing earthworm populations.
These results suggest that availability of food (cover crop material) was more important than the negative impact of tillage on earthworms. This shows the importance of providing food sources to promote earthworms and reveals another reason for promoting cover crops.
2. Soil Micro Fauna
Microarthropod sampling results were very similar in each of the 3 years of sampling, within the limits of the experimental design. Soil arthropod species richness in these annually cultivated fields is extremely low year-round compared to neighboring plant community types. The overall pattern is for low species richness in very early spring (at plowdown), followed by a peak just prior to or just following planting as colonists invade the agricultural fields from the surrounding habitat refuges, followed by a progressive decrease during the growing season until harvest time. This trend is true for all functional groups of soil-dwelling arthropods: predators, fungivores, and herbivores alike. Additionally there was a generalized regional effect on the entire experimental grid correlated with microtopography and water saturation during the winter months; those areas that were flooded more frequently generally had significantly lower populations of all soil microarthropod species (the effect persisting almost until harvest time).
During 2002, samples were taken twice; planting data samples showed a depressed effect (90% decrease) of the fallow treatment on total arthropods (especially springtails). Harvest-time samples revealed no treatment differences. Density of total arthropods (and most component groups as well) at harvest time was lower than that at planting.
During 2003, samples were taken twice; planting data showed a depressed effect of the fallow treatment on total arthropods (especially springtails). Conventional tillage decreased the total fauna, and there was a significant tillage x fallow interaction effect (fungivorous springtails and endeostigmatid mites are especially reduced). Samples at harvest time were significantly lower than at planting. By harvest time a significant increase in the fauna of strip-tilled versus conventionally tilled plots was recorded (holds for most taxa except Diabrotica cucumber-beetles, deep-soil Onychiurus springtails and predaceous micro-spiders). Predaceous gamasid mites, which revealed a strong negative effect of the fallow treatment at planting, retained this depletion still at harvest time.
During 2004, sampling was increased to 4 events to more fully document the seasonal trends. At plowdown, prior to planting, there was again a very significant decrease of total arthropods (especially springtails and macropredators) in the fallow treatment (90% decrease). By planting time, total densities remained rather similar (~10,000/m2), but for most functional groups of arthropods a significant difference between the strip-tilled (higher densities) and conventionally tilled treatments was apparent; the strength of this tillage difference was now stronger than the fallow difference. Several weeks later at canopy closure, total densities had dropped about 33% in all treatments and the only treatment difference that was significant was a higher density in the strip-tilled plots (true for total arthropods as well as nearly all component groups). Finally, at harvest time total density of arthropods had decreased about another 75% and any previous treatment differences were obscured (density ~650/m2).
During all three years the species richness of arthropods averaged about 10 species/650cm2 sample with a peak over 30 species/sample at planting time. During all three years the same two dozen commonest species maintained their general dominance relationships in tact.
It is logical to presume that the most important treatment affecting arthropod density is the presence of a cover crop during the winter; the cover crop functions primarily for refuging overwintering populations, but secondarily as a food supply for both fungivores, and indirectly for predators. This would be especially true if the experiment were carried out on an entire farm scale. The cover crop also exerts a huge effect at plowdown, providing a substrate for microbial metabolism as well as food for all the arthropods in the foodweb. The effect of this increased microbial metabolism is greatest probably around planting (as the soil progressively warms and dries); this is the time when immigration of additional soil-dwelling species takes place as well as the reproduction of the Isotoma springtails (the most abundant soil microarthropod in these soils). Without predation, which subsequently catches up to the Isotoma, population density can easily increase 100-fold within a two-week period (other studies by Moldenke). As the plowed-down substrate is used up, microarthropod populations decrease and by harvesttime the treatment effects are either very diminished or entirely erased. Between the canopy-closure and harvest-time samples, the beneficial effect of strip till is probably driven primarily by earthworms and the presence of leafy residue on the surface, which is the habitat for the second most abundant microarthropod, the springtail Entomobrya unostrigata.
The most apparent trend in the results is the correlation of soil microarthropod density and diversity with soil microbial activity and resources (e.g., plowed-down resources), NOT with the biomass of the roots of the crop. The results show a soil faunal response to cover cropping and reduced tillage, but cover cropping had the greater impact.
Soil Physical Properties
Water-stable aggregates (WSA) were measured as a percent change from the baseline measurements due to significant differences between plots prior to treatment implementation that were not accounted for by blocking Water-stable aggregates decreased over time in all treatments, although both cover-cropped treatments remained significantly higher than the fallow treatment at all sampling periods. Organic matter inputs can increase WSA by providing the “glues” to maintain aggregation and by stimulating biological activity. Cover crops provide additional organic matter to increase WSA, but reducing tillage had less of an effect to further increase WSA.
Between rows, bulk density was significantly greater (p < 0.05) in the strip-tilled plots than both conventionally tilled plots in the upper 10 cm. As this between-row soil is essentially under a no-till regime, the increase in bulk density can be attributed to an absence of tillage. Differences in physical soil response to tillage may well be linked to soil texture. Due to the silt content of this Chehalis silt loam soil, these between-row zones of compaction may be caused by a settling of silt particles during the long winter rainy season that results in a more compacted between-row zone.
Infiltration results varied widely both from year to year and within a treatment. This would suggest there is high spatial variability and that there is need for greater levels of subsampling. In year 2 there was a significant treatment effect with the cover- cropped/conventionally tilled plots having the lowest infiltration rate. The response of this soil property was less useful than the other soil properties in reflecting treatment effects and for understanding underlying mechanisms of how the various treatments may be affecting soil quality.
The problems of infiltration are likely related to high short-distance spatial variability. It may well be that greater subsampling is needed for this method. However, this is not easily done because this method is labor- and time-intensive and, depending on soil type, large amounts of water may be needed that are sometimes difficult to get to field sites. Consequently, from both a mechanistic or interpretation perspective and a practical application perspective, infiltration is not a good candidate for reflecting soil quality in our systems and soils of western Oregon.
Research and Integrated Vegetable Systems The most immediate response to the addition of cover crops and reduction of tillage was with the microbial properties and the soil faunal communities. This is due to the greater C inputs with cover cropping which stimulates the microbial community with added energy sources as well as food sources for soil fauna. Reducing tillage reduces disturbance, which protects habitat and results in less direct physical damage to organisms. This is important for branching organisms such as fungi which are particularly impacted by tillage..
The physical properties of WSA and compaction did not have the same response to the treatments as did the biological properties. WSA was consistently lower with conventional tillage but otherwise the results from WSA and soil compaction would indicate that reduced tillage actually had negative impacts on soil physical properties. The activity of soil organisms does drive the formation and stability of aggregates, which tends to run contrary to our results.
There may be several reasons for this. First it may simply be a function of time and that more time is needed to enable the higher levels of biological activity to have measurable effects on soil physical properties with reduced tillage. Second is the nature of the dominant soils in western Oregon and its climate. This is due in part to the silty nature of the soils in western Oregon that, over the winter rainy season, disperse in soils and fill pores. We are encouraged by evidence that there is greater earthworm activity with less disturbance and cover cropping, but this apparently is not enough (after 3 years) to offset compaction under the type of strip-till system we are using.
We have made considerable progress in identifying soil quality indicators. Soil enzyme activity and key soil fauna are sensitive to management effects. Also, as far as we know, this is the first research to show that midden counts can be a good index of earthworm activity. The advantage of this method is that it is simple and statistically robust and sensitive in picking up soil management effects.
Extension Activity We had extensive interactions with our cooperating farmers who were managing the on-farm research fields/demonstrations. We gained valuable insights into their perceptions of managing soils to improve soil quality. We are finding that their approach will continue to be more qualitative than quantitative as they are not likely to use more quantitative methods like the soil quality kit. We have used the portable soil quality kit on their farms, and we find it can be useful in detecting change. However, we do not believe it is realistic to expect farmers to use this kit on a regular basis. Informal discussions suggest they would use this kit for diagnostic situations and likely would be willing to pay for this service. At the same time they have interest in being able to verify that their soils have been managed for environmental quality and sustainability. Again there may be incentives to pay for services to assess soil quality if it can be linked to a marketing advantage for the produce.
June 24, 2004, we held a field day that was attended by farmers and university personnel. This was done at the OSU Vegetable Research Farm where we toured the SARE research plots. At the same time we had a series of simple posters that provided the results we have found for both on-farm and station research. We also, demonstrated the soil quality kit. Approximately, 35 people attended the meeting.
The biggest impact of the project has been to move farmers forward toward integrating cover crops and strip till. The on-farm research activities gave local visibility to these systems, and our farmers are advocates for using these more sustainable methods. Some growers have adopted a strip-till system that is deeper and this may overcome the compaction problems our research has identified. We presented our results at a number of extension meetings over the life of the project. In particular, we feel farmers are more aware of the biological component and have greater interests in managing earthworms to improve soil quality.
Educational & Outreach Activities
Dick, R.P., J. Sandeno, A. Taylor, R. Wagner, N. Pascoe, and T. Knight. 2002. Soil Enzyme Activity as a Sensitive Indicator of Ecosystem Disturbance. Abstracts, 17th World Congress of Soil Science, Bangkok, Thailand. August 14-21, 2002. p. 1056.
Seybold, C., and R.P. Dick. 2002. On-farm early indicators of cover crop effects on soil quality. Abstracts, 17th World Congress of Soil Science, Bangkok, Thailand. August 14-21, 2002. p. 1099.
Schutter, M.E., and R.P. Dick. 2002. Microbial community profiles and activities among aggregates of winter fallow and cover-cropped. Soil Sci. Soc. Am. J. 66:142-153.
Schutter, M., Sandeno, J., and R.P. Dick. 2001. Seasonal, soil type, and alternative management influences on microbial communities of vegetable cropping systems. Biol. Fert. Soils 34: 397-410
Dick, R.P., T. Knight, E. Ndiaye, A. Bandick, and J. Sandeno. 2003. Ecoystem stress – Thresholds and interpretation of soil enzyme technologies. Abstracts, Enzymes in the Environment, Praha, Czech Republic. July 14-17, 2003. p. 137
Tugel, A.J., S. Seiter, D. Friedman, J. Davis, R.P. Dick, D. McGrath, and R.R. Weil. 2001. Locally Led Conservation Activities: Developing a Soil Quality Assessment Tool. 529-534 pgs. In: D.E. Stott, R.H. Mohtar, and G.C. Steinhardt (eds). Sustaining the Global Farm – Selected papers from the 10th International Soil Conservation Organization Meeting, May 24-29, 1999, West Lafayette, IN. International Soil Conservation Organization in cooperation with the USDA and Purdue University, West Lafayette, IN. CD-ROM available from the USDA-ARS National Soil Erosion Laboratory, West Lafayette, IN. Web site http://topsoil.nserl.purdue.edu/nserlweb/isco99/pdf/isco99pdf.htm (verified 2 May 2002).
Banners, C.R., J.M. Sandeno, D.M. McGrath, A.R. Moldenke, R. Wymore, and R.P. Dick. 2003. Soil ecology and earthworms in an integrated reduced tillage/cover cropped vegetable system. In ASA-CSSA-SSSA Annual Meetings Abstracts, Denver, CO, November 2-6
Banners, C.R. 2005. Influence of integrated vegetable cropping system on soil quality. M.S. Thesis, Oregon State University, Corvallis OR
Cover crops are now widely used, with surveys showing 50% of vegetable ground being cover cropped (pers. comm. D. McGrath). In contrast, 15-20 years ago there was virtually no cover cropping. Our last 2 SARE projects have been important in making this happen. We do not know the extent of strip tillage, but our cooperating farmers are using this on all the crops that have been shown to be amenable.
Areas needing additional study
We have shown that earthworms can be stimulated by cover cropping. Longer studies with earthworms are needed under field conditions to determine the practical potential of using earthworms as soil engineers. We have established a set of microbial indicators that are sensitive to soil management. However, extensive field-scale research is needed to calibrate these methods as practicable and interpretable soil quality indicators.