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92-93 Final Report

Contents

 Introduction
 Grower Participation Key Element
 Replicated Research Station Experiments
 Data Collection
 Results
 Economic Analysis

		Oregon State University Coordinated On-Farm Research Program
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			Department of Horticulture Oregon State University, Corvallis, Oregon
	Introduction In an effort to accelerate knowledge and adoption of more economically viable, environmentally sound farming practices, a new program was initiated in the summer of 1992 by Oregon State University Cooperative Extension Service. This program, called the "Coordinated On-Farm Research and Demonstration Program," combines traditional Agricultural Experiment Station small-plot research activities with larger scale on-farm research in a continuum of information gathering, validation, and exchange. Funding for this program is provided by the Northwest Area Foundation, Minneapolis, Minn., Oregon Cooperative Extension Service, and the OSU Agricultural Experiment Station. Grower Participation Key Element Collaborative participation of an interdisciplinary team of growers, agribusiness representatives, governmental agency, Extension and university researchers is fundamental to this project. A major goal of the project is to enhance farmer participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four "focus sessions" were hosted by a lead farmer in each of three areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials. Twenty five growers, three process- ing industry representatives, an Oregon Department of Agriculture water quality specialist, and an interdisciplinary group of nine OSU Extension and research workers attended these meetings. Because of previously expressed interest among growers, these initial meetings focused primarily on practical approaches to integrate cover crops and other soil improvement practices into commercial vegetable production systems. Participating growers indicated several common needs and interests related to specific on-farm research/demonstration projects, including the following: Evaluation of on-farm research questions and appropriate methodologies for achieving relevant answers for farmers at reasonable levels of validation. Evaluation of various cover crop species and mixtures to give growers maximum flexibility in the integration of cover crops and conservation tillage into whole-farm systems. Innovative methods of cover crop establishment (e.g. interplanting into standing vegetable crops) to minimize work load competition during the busy harvest season. Quantifying the role of cover crops in nitrogen trapping and nitrogen con- tribution to following vegetable crops. New approaches of spring cover crop management to reduce tillage opera- tions and facilitate early vegetable crop plantings. Minimum tillage practices for direct seeding of vegetable crops into cover crops and cover crop residue.

Evaluating the impact of cover crops in weed suppression and arthropod pest management, and potential increases in pest incidence (i.e. slugs, cutworms) related to cover crops. Following these meetings, consultations were held with individual growers to determine specific experimental objectives, treatments, plot size, and variables of interest. Cover crop evaluation trials were established in late September on nine farms in Washington, Marion, Benton and Lane Counties. The crop rotational sequences and cover crops evaluated vary among the farms in the project. Typically on each farm 5 to 10 cover crop species or mixtures (grain and legume) were planted in large plot strips (0.5 to 2 acre strips). Twenty five different cover crop species, varieties, and mixtures were planted on the 10 farms. Spring- planted vegetable crops that will follow the cover crops in 1993 include sweet corn, beans, and cabbage. One on-farm trial involves evaluation of cover crops and in-row mulches for blueberries. Although not all cover crop species and combinations are planted on all participating farms, across farm replication will permit comparisons of several legumes, small grains, and legume/small grain mixtures. Replicated Research Station Experiments In addition to the on-farm research trials, four additional cover crop experiments are also being conducted on OSU research farms at Aurora and Corvallis. These replicated small-plot experiments permit researchers to examine cover crop performance under more controlled conditions. The OSU Cover Crop Trial, now into it's third year at Corvallis, is evaluating 22 species and varieties of cover crops for productivity and potential to trap leachable nitrogen from the soil. A long-term crop rotation experiment, also entering it's third year, has been established at the North Willamette Research and Extension center (NWREC) . This project examines single year as well as longer term economic and environmental aspects of several vegetable and cover crop rotations. Another experiment initiated in September, 1992 at NWREC, evaluates 14 winter-annual cover crop species and mixtures for their ability to "scavenge" nitrogen from the soil during the fall and winter months. A fourth experiment was initiated at Corvallis in October to develop and evaluate the integration of cover crops and conservation tillage systems for vegetable crop production. Data Collection Quadrat sampling was used to determine cover crop biomass accumulation rates sampled from November through May. On each sample date, four to six 0.25 m2 quadrat samples were randomly selected in each cover crop plot. Cover crops were clipped at the soil surface and separated by cover crop species. Samples were returned to the laboratory and oven dried at 100oF for 48-60 hours before weighing. Nitrogen accumulation by cover crops was evaluated at one mid-winter sampling date (in some fields) and in late April or early May, prior to spring tillage. The mid-winter sampling gives information on the relative ability of the cover crops to "scavenge" soil nitrogen that could otherwise be lost to leaching under the high winter rainfall conditions of the maritime Northwest. The spring sampling gives estimates of total nitrogen accumulated in the cover crop. At one farm (Keith Grover), soil nitrate content was sampled at 5 depths below the cover crops and fallow ground to evaluate the role of cover crops in reducing winter nitrate leaching. All data reported in this summary represent mean values (or averages). In the spring of 1993, interviews were conducted with participating growers to record their evaluations of cover crop growth, ease or difficulty of mechanical incorporation, methods of cover crop kill and tillage used, and other relevant observations. Three breakfast and dinner meetings were held in September, 1993, for further project evaluation and to define research objectives for 1993-94.

Results Biomass Accumulation: Cover crop growth and production of biomass and nitrogen varied dramatically among the farms involved in these trials. Generally, cover crops planted following irrigated vegetable crops emerged more quickly and produced more total growth than cover crops following wheat (eg. compare cover crop biomass on April 29 at the Grover Farm (Table 1) with cover crop biomass at the Duyck Farm (Table 7)). Many factors could be involved with these differences (in addition to differences in soil type), including soil moisture during establishment, nutrient immobilization from wheat or nutrient carryover from previous vegetable crops, and possible allelopathic activity from wheat residue. Cereal grain cover crops grew more quickly in the fall than legume crops; most legume growth was in the spring. Some cover crops produced more than 5 tons of dry matter by the second week of May (Table 1 and Table 4). Clearly, the longer the crops were allowed to grow in the spring, the greater the biomass. The unusually wet spring of 1993 delayed tillage operations. Soil moisture under cover crops was consistently higher than soil moisture in non-cover cropped plots. In some situations the cereal cover crops had become rather fibrous and difficult to incorporate, and under the wet conditions soils were being worked, had apparent effects of increasing clodding. Nitrogen scavenging and nitrogen accumulation: A number of researchers have recently reported on the role of cereal and grass cover crops to scavenge soil nitrate during the fall and winter and reduce nitrate leaching into the groundwater. In the study at the Grover Farm, soil nitrate sampling at one-foot intervals under the cover crops supported this observation (Table 3, Fig. 1). Soil nitrate concentrations were dramatically reduced under both barley and cereal rye cover crops when compared to the non-cover cropped fallow plot. Soil nitrate levels increased under the hairy vetch plots, however, suggesting an increased leakage of nitrogen from the legume. Adding the legume to rye in a mixture gave nearly identical reduction of nitrate leaching to rye alone; the addition of vetch to barley reduced soil nitrate concentrations, but not as well as rye and vetch mixtures. The increase of soil nitrate concentrations under vetch could be attributed to increased nitrogen contributions to the soil, and perhaps to increased area of soil macropores resulting from the enhanced earthworm populations under the vetch. Like biomass accumulation, total nitrogen accumulation of the cover crops depended on site and on when cover crop growth was terminated. The legume cover crops typically grow slowly during the winter, then grow rapidly in the spring. For example, hairy vetch biomass jumped from 2,323 lbs/acre on April 29 to 6,171 lbs/acre on May 13 at the Grover Farm (Table 1); from 2,406 lbs/acre on April 15 to 5,100 lbs/acre on May 11 at the DeCou Farm (Table 4); at the Sheelar Farm, biomass of Austrian field peas doubled from April 1 to April 28. Time of cover crop termination also influences the carbon to nitrogen ratio of the cover crops. This is particularly true of the cereals, which can have very high C:N rations (eg. 40:1 or 50:1) after they begin seed formation. Generally, high C:N ratios bring about nitrogen immobilization in the soil. Low C:N ratios, such as 15:1, mean the cover crop can be mineralized rather quickly by soil microorganisms and the nitrogen made available to crop uptake. No determination of C:N ratios were made in this study, however. Legume cover crops produced from 28 to 186 lbs total nitrogen per acre, depending on the crop, field, and termination date. Clearly, for significant N contributions to the following vegetable crop to occur, the legume must be allowed to grow until mid-April or early May. Economic Analysis Estimating economic benefits of cover crop use is difficult because of the multiple effects on cover crops on soil productivity beyond a single year. The ability of cover crops to improve water infiltration and soil water holding ability is well documented, as are the beneficial effects of increased organic matter to the soil

biological community and to nutrient cycling. Other potential economic benefits include reduced soil erosion and increased weed and insect pest control. There are also detrimental effects, including delayed planting, possible yield suppression from allelopathy and nutrient immobilization, and increased pest abundance. Although these multiple impacts of cover crops are known, the ability to translate these interactive, multiple-year effects into a economic terms has not been possible. More direct, short-term economic impact can be derived, however, when looking at nitrogen contribution of legume cover crops to the succeeding cash crops. Again, in single-year experiments, long-term contributions are ignored. In this project, we have focused on collecting data on costs of cover crop, including both costs of establishment and costs associated with tillage prior to cash crop planting. For the latter estimates, some of these costs would also be incurred regardless of whether a cover crop was grown and should be adjusted based on expected tillage operations under a fallow situation. Cost Estimation. Cover crop costs were estimated for each farm using the following methods. Farmer-cooperators reported the operations used on their individual farms. The cost of the seedbed preparation procedures for the cover crop and the cash crop which followed were estimated modifying estimates for the same cultural operations in various OSU enterprise budgets for the Willamette Valley. Adjustments to budget estimates include incorporating machinery used by cooperators, and adjusting the time needed to complete the operations. Cost assumptions are reported in Table 1 by machinery type used. On one farm cover crop seeds were manually broadcast, no machinery type was indicated for this operation; all costs associated with this operation were assumed to come from labor and seed cost. On some farms the operations for seedbed preparation for the cash crop were not reported. The price of cover crop seeds came from local seed outlets. Seed prices were used to calculate the per pound price of mixes cooperators reported to use. Many of the farmers raised their own seeds and traded these seeds with other farmers. The cost of these seeds were estimated at current market prices. One farmer used three year old seed, the market value for this seed was set at zero. Farmers reported the application rate per acre for each seed variety and mix they used. Table 1 displays seed prices for each variety and mix used by the per pound cost and the cost per acre as applied in this study. Ideally the cost of seedbed preparation for the cash crop following the cover crop should be compared with the average cost of seedbed preparation without the cover crop for each farmer. However, costs without cover crops were not available. The cost estimates given in enterprise budgets for each cash crop were used as a proxy of seedbed preparation costs for cash crops not following a cover crop. The difference between costs given in the enterprise budgets and cost estimates for procedures reported by the farmer-cooperators were compared, and the difference attributed to the cost of the cover crop. The difference in cover crop costs between farms is primarily a function of the number of times a farmer disked the land during seed bed preparation for the cover crop, with smaller differences due to seed variety and mix chosen. Results. The average cost of incorporating a cover crop into a vegetable rotation is $55.23 per acre (variable cost $35.66/acre) before incorporation of the green manure, and $100.13/acre (variable cost $59.70/acre) after all seedbed preparation for the cash crop. The variation in costs is primarily caused by the number and kinds of tillage operations before planting both the cover crop and the cash crop. Smaller variations were caused by the choice of seed variety and seeding rate. The standard deviation fro the average total cost through planting the cover crop was 16.70 (standard deviation for the variable cost was 14.22). The standard deviation for the average cost to the plant of the cover crops was 29.07 (sd variable cost 17.38). Cover Crop Management in Vegetable Crop Systems

		As growers participating in the project clearly stated during the focus sessions, the reasons for growing cover crops vary considerably. Maintaining and improving soil tilth through organic matter addition was a common goal, with nitrogen scavenging for water quality and nitrogen contributions from legumes as secondary goals. The development of whole farm cover crop management plans will vary among farms, with field-specific plans depending on crop rotation sequences, soil type, and particularly, the projected planting date of the cash crops to be planted in the spring. For example, an early-planted vegetable crop might be planted to a cereal cover crop in the fall and killed with glyphosate in the late winter. A late-planted sweet corn or broccoli crop might utilize a cereal- legume mixture to accomplish both water quality and N-fixation goals along with maximizing organic matter accumulation. The selection of appropriate tillage practices for cover crop incorporation in the spring is also of interest in this project. Participating growers use a wide variety of tillage practices, from conventional tillage using moldboard plowing, disking, and rotovating, to more conservation tillage practices of chisel plowing or disking with cover crop disks. The exceptionally wet spring of 1993 made evaluation of reduced tillage practices particularly difficult, since soils were kept extremely wet. Farmers with 1-2 tons of cover crop biomass (eg. Sheelar and Duyck) experienced far less difficulty in cover crop incorporation than growers with 4-5 tons of biomass. Many of the participating growers expressed interest in the selection of cereal varieties that would produce lower quantities of biomass, or would winter kill (such as spring oats), or would grow rapidly in the fall and die before the spring in order to minimize spring growth of the cereal crop. On-farm trials in 1993-94 are examining some of these options.
		Data Collection: Quadrat sampling was used to determine cover crop biomass accumulation rates sampled from November through May. On each sample date, four to six 0.25 m2 quadrat samples were randomly selected in each cover crop plot. Cover crops were clipped at the soil surface and separated by cover crop species. Samples were returned to the laboratory and oven dried at 100oF for 48-60 hours before weighing. Nitrogen accumulation by cover crops was evaluated at one mid-winter sampling date and in early May, prior to spring tillage. This mid-winter sampling gives growers information on the relative ability of the cover crops to "scavenge" soil nitrogen that could otherwise be lost to leaching under the high winter rainfall conditions of the maritime Northwest . At two farms (Grover and Krebs) and in a replicated experiment at the North Willamette Research and Extension Center, soil nitrate content was sampled at 5 depths below the cover crops and fallow ground to evaluate the role of cover crops in reducing winter nitrate leaching.
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		Location: Salem, OR. Soil Series: Cloquato silt loam Previous Crop: Onions Cover Crop Seeding Rates (lbs/acre): Barley (cv. Belford) 133; Rye (cv. common) 73; Hairy vetch 27; Barely + vetch 64/12; Rye + vetch 57/17. Hairy vetch was innoculated with Rhizobium leguminosarum, but was not mechanically scarified. Planting Date: September 29, 1992 Experimental Design: Randomized, unreplicated plots 96 x 800 ft. Table 1. Seasonal cover crop biomass accumulation, Grover Farm, Salem, OR.

		Table 2. Above-ground nitrogen accumulation by cover crops, Grover Farms, 1993.
		Table 3. Soil nitrate concentrations (ppm NO3 )following various winter annual cover crops planted the previous fall. Data were taken on March 11, 1993. Ten samples per soil depth were taken in each cover crop strip and composited for analysis. Soil nitrogen analysis was performed by the OSU Central Analytical Laboratory.

		Fig. 1. Soil nitrate concentrations (ppm NO3 ) following various winter annual cover crops planted the previous fall, sampled March 11, 1993 (Grover Farm).
		Location: Junction City, OR Soil Series: Malabon silty clay loam Previous Crop: Garlic Cover Crop Seeding Rates (lbs/acre): Fava beans 153; crimson clover 16; hairy vetch 24; fava beans + oats 153/76; fava beans + cereal rye 153/73; fava beans + annual ryegrass 153/23; fava beans + barley 153/70; crimson clover + oats 16/76; crimson clover + cereal rye 16/73; crimson clover + barley 16/70; crimson clover + annual ryegrass 16/23; hairy vetch + oats 24/76; hairy vetch + cereal rye 24/73; hairy vetch + barley 24/70; hairy vetch + annual ryegrass 24/23. Hairy vetch seed was mechanically scarified and innoculated with Rhizobium leguminosarum; crimson clover and fava beans were not innoculated. Planting Date: October 9, 1992 Experimental Design: Three legumes (fava beans, hairy vetch, and crimson clover) were drilled in 36-ft x 600-ft strips. Perpendicular to and across these strips, four varieties of grasses or grains were planted in 120-ft wide strips.

This gave 15 cover crop treatments; three with legumes only, and 12 with mixtures of legumes plus grains or grasses. Table 4. Seasonal accumulation of cover crop above-ground biomass and nitrogen, DeCou Farm, Junction City, OR.

		a Growth of crimson clover and hairy vetch was minimal at the January date and these plots were not sampled. b Component cover crops of the mixtures were not separated on the March and April sampling dates. c The Poco barley matured by mid-April and all plots containing barley were mowed to prevent the barley from setting seed. d Due to a laboratory sampling error, actual percent nitrogen data from vetch samples are not available. Percent nitrogen figures are from the 1993 OSU cover crop trial at Corvallis.

			Table 5. Mid-winter nitrogen accumulation in cover crop above-ground tissue, DeCou Farm, sampled February 6, 1993. Note: Growth of crimson clover and hairy vetch was minimal at the January date and these plots were not sampled.
			Location: Forest Grove, OR. Previous Crop: Winter wheat, 1991-92 Cover Crop Seeding Rates (lbs/acre): Oats (cv. Cayuse) 110; Austrian field peas 53; Hairy vetch 21; Oats (cv. Cayuse) + hairy vetch 64/31; Oats (cv. Cayuse) + Austrian field peas 67/45. Hairy vetch was innoculated with Rhizobium leguminosarum. Austrian field peas were not innoculated. Planting Date: October 2, 1992 Experimental Design: Randomized, unreplicated plots 48' x 770 ft.
			Location:	Forest Grove, OR

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		Soil Series: Woodburn silt loam Previous Crop: Wheat Cover Crop Seeding Rates (lbs/acre): Oats (cv. Cayuse) 89; Austrian winter peas 101; Hairy vetch 16; Oats + hairy vetch 57/26; Oats + Austrian winter peas 63/42. Hairy vetch seed was mechanically scarified and innoculated with Rhizobium leguminosarum. Austrian field peas were not innoculated. Planting Date: October 9, 1992 Experimental Design: Randomized, unreplicated plots 48 x 660 ft.
		Location: Corvallis, OR. Soil Series: Chehalis silty clay loam Previous Crop: Winter wheat, 1991-92. Cover Crop Seeding Rates (lbs/acre): Fava beans (cv. Banner) 154; Crimson clover 16; Austrian field peas 53; Barley (cv. Belford) + Austrian field peas 56/40; Barely (cv. Poco) + Austrian field peas 50/36. Crimson cover was innoculated with Rhizobium meliloti and R. rifolii. Austrian field peans and fava beans were not innoculated. Planting Date: October 5, 1992 Experimental Design: Randomized, unreplicated plots 48 x 740 ft. Comment: Poor growth of Austrian field peas in this trial may be due to low quality seed, since reduced growth was observed in other fields planted with the same seed lot.

			a Nitrogen analysis performed on samples taken April 29. b Due to a laboratory sampling error, actual percent nitrogen data from vetch and Austrian field pea samples are not available. Percent nitrogen figures are from the 1993 OSU cover crop trial at Corvallis.
			Location: Jefferson, OR. Previous Crop: Sweet corn Cover Crop Seeding Rates (lbs/acre): Rye grain 150; Barley (cv. Steptoe) 100; Annual ryegrass 25. Planting Date: October 10, 1992. Experimental Design: Randomized, unreplicated plots 120 x 1,500 ft.
			Location: Turner, OR. Soil Series: Cortney silt loam Previous Crop: Sweet corn Cover Crop Seeding Rates (lbs/acre): Oats (cv. unknown) 60; Austrian winter peas 50; Barley (cv. Steptoe) 60; Planting Date: October 29, 1992 Experimental Design: Randomized, unreplicated plots 100 x 1,100ft. Comment: Phytotoxic symptoms, possibly of carryover triazine damage was observed in the oat stand in November, most likely causing yield reductions. Table 10. Seasonal accumulation of cover crop above-ground biomass, Beldon Farm, Turner, OR.

			Location: Albany, OR. Soil Series: Chehalis silty clay loam Previous Crop: Wheat Cover Crop Seeding Rates (lbs/acre): Barley (cv. Steptoe) + hairy vetch 80/20; Oats (cv. Cayuse) + hairy vetch 80/20; Triticale (cv. Flora) 92; Barley (cv. Micah) 121; Austrian winter peas 102; Annual ryegrass 20; Hairy vetch 31; crimson clover 11. Hairy vetch was mechanically scarified and innoculated with Rhizobium leguminosarum; clover was innoculated with R. meliloti and R. trifolii. Austrian field peas were not innoculated. Planting Date: October 7, 1992. Experimental Design: Randomized, unreplicated plots 20 x 2100 ft. Comment: Winter flooding in this river bottom field, coupled with slug damage in early winter, severely reduced the stands of most of the cover crop strips planted in this trial.
			a Actual laboratory-derived values used here for percent nitrogen, since the harvest date was significantly later than the harvest date of hairy vetch at the OSU cover crop trial in Corvallis.
			Location: Noti, OR. Soil Series: Veneta variant silt loam Previous Crop: Blueberries (Continuing in blueberries) Cover Crop Seeding Rates (lbs.acre): Oats (cv. Walkin) + common vetch 84/36; Barley (cv. Poco) + common vetch 70/30; Cereal rye (cv. unknown) + common vetch 70/30. Planting Date: September 21, 1992. Experimental Design: Unreplicated strips between blueberry rows, 4' x 380'.

Comments: Because of the growth of winter annual weeds (particularly chickweed) in the plots, sampling was not conducted at multiple sample dates. One sampling was conducted on May 5, 1993, and weeds were separated from the cover crops. 'Poco' barley was killed by low winter temperatures.

Project Managers/Coordinators John Luna, Sustainable Agriculture On- Farm Research Coordinator, Dept. of Horticulture, Oregon State University, Corvallis, OR. 97331 Dan McGrath, Extension Agent, Vegetable Crops, Marion County Cooperative Extension Service, 3180 Center St. NE, Salem, OR 97301 Ray William, Extension Weed and Vegetation Management Specialist, Dept. of Horticulture, Oregon State University, Corvallis, OR. 97331. Oregon State University Participants Richard Dick Associate Professor Crop and Soil Science Tim Cross Extension Agricultural Economist Agricultural and Natural Resource Economics Russ Karow Extension Agronomist Crop and Soil Science Stefan Seiter Graduate Research Assistant, Dept. of Horticulture Robert Rackham Benton County Cooperative Extension Service, Corvallis, OR. 97330 Ross Penhallegon Lane County Cooperative Extension Service, Eugene, OR 97402 Neil Rambo Washington County Cooperative Extension Service Hillsboro, OR Farmer Participants Jim and Ben Beldon	Beldon Farms Turner, OR Bill and Karla Chambers 3122 Stahlbush Island Rd. Corvallis, OR 97333 Keith Grover 7515 22nd Ave. N. Salem, OR 97303 Peter and Cliff Kenagy 1640 Nebergall Loop Albany, OR 97321 Jack Grey and Wali Via 89762 Poodle Creek Rd. Noti, OR 97461 Ken Krebs 3542 Wintel Rd. S. Jefferson, OR 97352 Dave DeCou 93780 River Rd. Junction City, OR 97448 Gail Sheelar 1265 N. W. Gales Creek Rd Forest Grove, OR 97117 Tom Duyck Rt 2 Box 392, Forest Grove, OR Agribusiness and Agency Cooperators Marc Peters Oregon Department of Agriculture Salem, OR Andrew Bennett NorPac, Inc. Salem, OR 97301

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