Integrated evaluations of minimum disturbance production systems in California's San Joaquin Valley

Goals / Objectives
The research project proposed here will compare conservation tillage and conventional tillage practices in crop rotations common to the SJV's West Side in terms of farm productivity and profitability, key soil quality indicator properties; pest and crop management requirements, and the potential for improving air quality, and will widely disseminate information related to the background, goals and outcomes of the proposed study.

Project Methods
Despite a 300% increase in conservation tillage (CT) production in the Midwest during the past decade, less than 0.3% of the acreage in California's San Joaquin Valley is currently farmed using CT practices. Preplant operations typically account for 18-24% of overall production costs for annual crops grown in the West Side region of the San Joaquin Valley (SJV). An average of about 9 to 11 tillage-related passes are routinely done during the fall-spring period to prepare the soil for summer cropping. These passes represent not only considerable energy, equipment and labor costs, but recent research indicates that tillage reduces soil organic matter (SOM) and emits considerable respirable dust as well. Because SOM is widely regarded as an important attribute of good soil quality and long-term productivity, interest has been growing over the last several years, in developing alternative production systems that reduce costs while at the same time improve the soil resource through greater carbon sequestration. Furthermore, no data exits on potential benefits of reduced tillage production systems in terms of mitigating airborne respirable dusts that are known to result from heavily tilled agricultural production systems. Conservation tillage systems may serve to increase SOM levels, reduce production cost and improve air quality in this critically important agricultural production region.

Progress 10/01/99 to 09/30/04

Outputs
Less than 1 percent of row crop acreage in California is currently farmed using conservation tillage (CT) practices. Adoption of CT systems in California has, however, recently been seen as a potential means for improving profitability and reducing energy use and a number of research, demonstration and evaluation initiatives have recently been started to explore a variety of cropping system options for reducing tillage. In the fall of 1999, we established a 3.2 hectare field experiment comparing conservation and standard tillage (ST) cotton and tomato production systems with and without winter cover crops at the University of California West Side Research and Extension Center in Five Points, CA in terms of 1) farm productivity and profitability, 2) soil quality indicator properties, 3) soil water relations, the quantity and composition of dust produced, and 4) pest and crop management requirements. Current standard production systems for these crops in this region are quite tillage and energy-intensive and virtually no experimental work has been done to evaluate potential alternatives in this critically-important agricultural production valley. To date, this NRI study has demonstrated that planting and harvesting crops with conservation tillage systems is possible given some equipment modifications and that yields can be maintained relatively close to those of standard tillage in CT crop residue environments. CT resulted in net savings of about $80 per acre annually from fuel, labor, repairs and equipment ownership. Yields and net income were higher for CT than ST for tomato but lower for cotton. Dust (total and respirable) emissions associated with the various tillage operations that were used in each production system were lower in the CT systems relative to the ST systems. Five peer-reviewed publications have been prepared based on this work and it has provided material for more than 300 extension education presentations.

Impacts
This project is the first to evaluate tillage system alternatives in Californias Central Valley in a comprehensive way. It seeks to provide full cost accounting of potential economic and environmental benefits of cropping systems alternatives which are gaining considerable interest, but for which we currently have little experimental or comparative information.

Publications

Mitchell, J.P. 2004. Research and extension education related to conservation tillage in Califonria. Field tour and oral presentation to 19 students of Denmark Agricultural Science University. May 27, 2004 Five Points, CA.
Mitchell, J.P 2004. Conservation tillage in intensive California agriculture. Invited presentation at the USDA Natural Resources Conservation Service National Agronomists Conference. Lied Conference Center. June 15, 2004 Nebraska City, NE. 45 particpants.
Mitchell, J.P. 2004. Conservation tillage in California: An overview. Presentation for Intern of USDA Associate Director, Mack Gray, John Beyer and Johnnie Siliznoff. July 1, 2004 Five Points, CA.
Mitchell, J.P. 2004. Reduced tillage tomato production. 2004 Warm season vegetable field day. UC West Side Research and Extension Center. July 14, 2004 Five Points, CA. 150 participants.
Mitchell, J.P. 2004. Reduced tillage cotton and tomato production systems evaluations in California. JPM prepared 38-slide Powerpoint presentation for Dan Munk to present). 2004 Beltwide Cotton Conferences, January 4, 2004, Marriott River Center, San Antonio, TX.
Mitchell, J.P. 2004. Conservation tillage and environmental protection. Invited presentation. 96th Tomato Day. University of California, Davis. January 8, 2004 Buehler Alumni Center. 70 participants.
Mitchell, J.P. 2004. Conservation tillage in dairy forage production systems. Presentation for Denele Agricultural Labs and Sustainable Conservation. January 19, 2004 Hilmar, CA. 5 participants.
Mitchell, J.P. 2004. What is conservation tillage and why might it be an important means for improving San Joaquin Valley air quality? Invited presentation to USDA Natural Resources Conservation Service San Joaquin Valley Air Quality Coordinators. Fresno County Farm Bureau. January 21, 2004 Fresno, CA.
Mitchell, J.P. 2004. Conservation tillage forage production systems. Invited presentation and discussion facilitation for California Dairy Campaign. Zylstra Dairy, January 26, 2004 Turlock, CA. 12 particpants.
Mitchell, J.P. 2004. Conservation tillage in dairy systems. Invited presentation to Mark and Mrs. Skinner, Donald Collins and Carol Rush. January 27, 2004 Buttonwillow, CA.
Mitchell, J.P. 2004. Conservation tillage cotton and forage production. Presentation to Mike OBannion. January 27, 2004 Dos Palos, CA. 3 participants.
Mitchell, J.P. 2004. Sustainable tomato production in California. Introductory discussion for Liz Mann, Australian Tomato Commission and Chuck Rivara, California Tomato Research Institute. February 4, 2004 Walnut Grove, CA.
Mitchell, J.P. 2004. Conservation tillage corn production. CT Corn Produciton Meeting. Western Farm Service. Wimpys Restaurant. February 4, 2004 Walnut Grove, CA. 60 participants.
Mitchell, J.P. 2004. Introduction to CT Workgroups equipment and activities. Oral introduction provided to Dan Marcum, UCCE Farm Advisor. February 4, 2004
Mitchell, J.P. 2004. Invited presentation discussion for NRCS Stanislaus County, February 12, 2004 Modesto, CA. 4 farmers and 2 NRCS staff.
Mitchell, J.P. 2004. Annual Address. CT Workgroup Annual Meeting, February 18, 2004 Davis, CA. 45 participants.
Mitchell, J.P. 2004. Innovative tillage options: Making cotton more profitable in the SJV. Presentation to Cotton Incorporated State Support Committee. March 4, 2004 Tulare, CA.
Mitchell, J.P. 2004. CT Workgroup. Poster presentation. Annual Meeting of the California Cotton Growers and Ginners Associations. March 9, 2004 Visalia, CA. 200 participants.
Mitchell, J.P 2004. Borba Farms Cotton Study. Poster presentation. Annual Meeting of the California Cotton Growers and Ginners Associations. March 9, 2004 Visalia, CA. 200 participants.
Mitchell, J.P. 2004. Sustainable food production systems. Invited field presentation to UC Berkeley students with John Diener. About 15 UCB students who were part of a student-organized tour class on food systems. March 22, 2004
Mitchell, J.P. 2004. CT production for Mark and Mrs. Skinner and Donald Collins and Carol Rush. NRCS EQIP Project. March 30, 2004 Bakersfield, CA.
Mitchell, J.P. 2004. Conservation tillage. Oral presentation to USDA NRCS, Western Farm Service in NRCS office, April 2004 Sacramento County. Invited by Christian Davis.
Mitchell, J.P 2004. Presentation and tour for Steve Werblow. Writer for California Farmer and The Furrow. April 21, 2004
Mitchell, J.P. 2004. Conservation tillage research of the University of California. Presentation to Conservation Tillage Field Day. Introductory presentation to Imperial Valley growers, equipment company representatives and Cooperative Extension. May 20, 2004 50 participants. 2 handouts.
Mitchell, J.P. 2004. The Conservation Tillage Workgroup: Working to reduce dust by tilling less. Invited presentation at the San Joaquin Valley Dust Control Products and Equipment Show. Dos Palos Cooperative Cotton Gin. July 21, 2004 Dos Palos, CA. Sponsored by the California Association of Resource Conservation Districts.
Mitchell, J.P. 2004. Conservation tillage and environmental quality. Invited speaker. Conservation tillage field day and barbeque. Zylstra Dairy and Charles Ahlem Ranch, August 24, 2004 Hilmar, CA. 50 participants.
Mitchell J.P. 2004. Conservation tillage in California. Oral plenary session presentation at CT2004: Western States Conservation Tillage Conference. September 8 & 9, 2004 Five Points, CA. 270 participants.
Mitchell, J.P. 2004. Resource conservation issues and opportunities for CT in Colusa County Reconnaissance Survey Meeting. Invited presentation to Colusa County RCD, NRCS and UCCE. September 22, 2004

Progress 01/01/03 to 12/31/03

Outputs
Less than 1% of row crop acreage in California is currently farmed using conservation tillage (CT) practices. Adoption of CT systems in California has, however, recently been seen as a potential means for improving profitability and reducing energy use and a number of research, demonstration and evaluation initiatives have recently been started to explore a variety of cropping system options for reducing tillage. In the fall of 1999, we established a 3.2 hectare field experiment comparing conservation and standard tillage (ST) cotton and tomato production systems with and without winter cover crops at the University of California West Side Research and Extension Center in Five Points, CA in terms of 1) farm productivity and profitability, 2) soil quality indicator properties, 3) soil water relations, the quantity and composition of dust produced, and 4) pest and crop management requirements. Current standard production systems for these crops in this region are quite tillage and energy-intensive and virtually no experimental work has been done to evaluate potential alternatives in this critically-important agricultural production valley. To date, this NRI study has demonstrated that planting and harvesting crops with conservation tillage systems is possible given some equipment modifications and that yields can be maintained relatively close to those of standard tillage in CT crop residue environments. Data from this study indicate that tomato yields in the CT + cover crop systems were also similar to those in the standard till plots, with an elimination of six tillage operations following the prior years cotton crop in the CT plots relative to the standard till systems. Cotton yields on average, have been reduced from 8 to 18% in the CT cover crop and CT + cover crop systems relative to the standard tillage control system, however, there was an elimination of 8 or 9 tillage operations in the CT systems relative to the ST approach following the tomato crops. Estimated resource use per acre (hours of labor and gallons of fuel) indicate the possibility of the CT systems to reduce these inputs relative to the standard till systems. Dust production associated with the various tillage operations that were used in each production system was lower in both the CT systems relative to the standard tillage systems. This study is the first of its kind in California to systematically compare tillage system alternatives through a crop rotation. This research site has yielded over 120 presentations over the last year and work during the first four years of this study is now being compiled for publication.

Impacts
This project is the first to evaluate tillage system alternatives in Californias Central Valley in a comprehensive way. It seeks to provide full cost accounting of potential economic and environmental benefits of cropping systems alternatives which are gaining considerable interest, but for which we currently have little experimental or comparative information.

Publications

March 13, 2002. Presentation to Dave Robbing, Wastewater Concepts, Inc. Provided presentation on conservation tillage to Mr. Robbins who is consulting with the Ministry of Agriculture in the Phillipines. University of California West Side Research and Extension Center, Five Points, CA.
March 14, 2003. Development and extension of conservation tillage production practices for processing tomatoes. Pp. 9 to 12. 2002 Annual Project Report. California Tomato Research Institute.
March 26, 2003. Does conservation tillage reduce dust emissions in specialty crop rotations in Californias San Joaquin Valley? Quarterly Report to the CDFA Specialty Crop Program.
April 1, 2003. Conservation tillage innovations. USDA Natural Resources Conservation Service. Solano County. Invited discussion presentation. Organized by Sally Negroni and Walt Cheechov.
April 23, 2003. Conservation tillage. Prepared presentation notes and poster materials for UCCE Farm Advisor, Dan Munk, to make presentation on conservation tillage and soil erosion as part of the Soil Erosion Management: A free field day for farmers and other land owners field day at William and Jon Schmidts Farm, 6890 West Oakdale Road, Winton, CA. Merced County. Invited presentation by Community Alliance with Family Farmers.
May 2, 2003. Conservation tillage: Implications for air quality improvement in the San Jaoquin Valley. Part of field tour: Air Quality. California Chapter of Soil and Water Conservation Society Annual Conference. Assessing San Joaquin Valley Resource Concerns. Invited presentation. Ramada Inn. Fresno, CA. 15 participants.
May 22, 2003. Conservation tillage soil management. Invited presentation at FARMS Fresno County. Five Points, CA. 30 participants.
June 11, 2003. Conservation tillage corn and tomato work within the Long-Term Research on Agricultural Systems (LTRAS) Project. Invited presentation to the UCCE Processing Tomato Workgroup 2003 Summer Tour. Davis, CA. 8 participants.
June 16, 2003. Preharvest management influences on postharvest quality of fruits and vegetables. Postharvest Technology Short Course. PLB 196. University of California, Davis. 50 participants.
June 24, 2003. PLB 196 Postharvest Technology Short Course San Joaquin Valley Tour Host. Visalia to Bakersfield, CA. 60 participants.
June 26, 2003. Summary of Conservation Tillage Workgroup Activities 2003. Annual CT Workgroup CT2003 Conference Planning Meeting. Davis, CA 16 participants.
June 27, 2003. Summary of Conservation Tillage Workgroup Activities 2003. Annual CT Workgroup CT2003 Conference Planning Meeting. Five Points, CA. 16 participants.
August 27, 2003. Hosted field tour of San Joaquin Valley conservation tillage research and farm demonstration sites for Alan Kale and Jamie Thompson. Wattie Heinz New Zealand. Five Points, CA.
July 1, 2003. History of surface mulch systems. Field Presentation at Sun Pacific Farms, Firebaugh, CA. 18 participants.
July 22, 2003. Sustainable agriculture research and extension education in California. Invited presentation for Unilever Best Foods North America. Five Points, CA. 3 participants.
July 23, 2003. Growth and development of reduced tillage production systems in California (Special reference to rotations containing cotton). Invited presentation to California Department of Food and Agriculture Pink Bollworm Management Committee. Fresno, CA. 40 participants.
July 31, 2003. Growing tomatoes as cheaply as possible: Reduced till approaches (Weed management issues discussed) and equipment demonstration. 2003 Fresh Market Tomato Field Day and Barbeque. LeGrand, CA. 50 participants.
August 19, 2003. Reduced tillage practices in the growth of processing tomatoes. Processing Tomato Field Day. UC West Side Research and Extension Center, Five Points, CA. 30 participants.
September 17, 2003. Reduced tillage cover crop mulch tomato system evaluation at Sun Pacific in Firebaugh, CA. Sheraton Grand Hotel, Sacramento, CA. California Tomato Commission Annual Meeting Research Presenation. 30 participants.
September 18, 2003. Reduced till cotton systems evaluations. 2003 Cotton Field Day. Five Points, CA. 80 participants.
September 28, 2003. Farmers, researchers look at reduced till systems. Article for Daily Democrat Newspaper. Submitted to Phil Hogan, USDA NRCS.
January 15, 2003. Crop Management Innovation. In Crop Management and Marketing Alternatives Seminar. 2003 Intermountain Agricultural Conference. Klamath, Falls, OR. Invited Keynote Speaker.
January 17, 2003. Minimum or conservation tillage crop production systems. (Receng innovations in the Central Valley. Oral presentation for conservation tillage and corn meeting. Sponsored by Western Farm Service. Wimphys Restaurant. Walnut Grove, CA. 50 participants. Invoted Keynote Speaker.
March 11, 2003. Weed pressure in tomato and cotton rotations transitioning to conservation tillage in Californias San Joaquin Valley. J.P. Mitchell, K.J. Hembree, N.Va and R.G. Vargas. Western Society of Weed Science. Sheraton Kauai Resort. Kauai, HI. Paper prepared by JPM. Presented by Vargas.
March 11, 2003. Soil quality and conservation tillage in California. Invited presentation at Soil Quality Roundtable. USDA Natural Resources Conservation Service California Conservationists and USDA NRCS Soil Quality Institute Representatives, Bill Puckett and Susan Andrews. Davis, CA. 20 participants.
March 12, 2003. Organized and led field tour of Californias Central Valley for USDA Natural Resources Conservation Service Soil Quality Institute personnel Bill Puckett and Susan Andrews and California NRCS staff, Diane Holcomb, Dave Smith and Ken Oster. Tour stops / sites included LTRAS site with Steve Kaffka, Red Rock Ranch with Ray Melgoza, Borba Farms with Bob Prys and UC West Side Research and Extension Center with Dan Munk.
January 22, 2003. Soil Quality. Invited class lecture to Plant Science 253. California State University, Fresno. 9 participants.
January 22, 2003. Conservation tillage as a cost share practice. Invited presentation at the Yolo County Natural Resources Conservation Service Stakeholder Meeting. Woodland, CA. 45 participants.
January 28, 2003. Provided technical information input to USDA Natural Resources Conservation Service to have conservation tillage endorsed as a cost-share practice in their USDA NRCS Environmental Quality Incentives Program as part of the 2002 Farm Bill. John Beyer, Ron Harben and Bob Fry.
January 30, 2003. The case for conservation tillage in the Central Valley (How the Conservation Tillage Workgroup might help efforts to establish the San Joaquin Valley Resource Conservation and Development Area and Council). University of California Center. Fresno, CA. 40 participants
February 10, 2003. Conservation tillage / Strip tillage in California. Presentation to Case DMI. Dave Martin, Rob Zumwalt and other representative from Case DMI. Tulare Farm Show, Tulare, CA.
February 21 and 22, 2003. Served as Advisory Committee Member on the New Farm Program at the Rodale Institute, Kutztown, PA. 20 participants.
February 24, 2003. Conservation tillage as a means to improve air quality in the San Joaquin Valley. Invited presentation to the San Joaquin Valley Air Quality Task Force. Fresno, CA.
February 25, 2003. Conservation tillage initiatives in California. USDA Natural Resources Conservation Service. West Region Agronomy Consortium. Invited presentation. Pacific Grove, CA. 40 participants.
February 28, 2003. Annual Address. Conservation Tillage Workgroup Meeting. Davis, CA. 60 participants.
February 28, 2003. Moderator. Conservation Tillage Workgroup Meeting. Davis, CA. 60 participants.
February 28, 2003. Strip till and cover crop tomato production systems in Gustine, CA. JPM prepared and did presentation of Jeff Dolan at the 2003 CT Workgroup Meeting. Davis, CA. 60 participants.
February 28, 2003. Longstanding and ongoing next generation conservation tillage research in Five Points, CA. 2003 Workgroup Meeting. Davis, CA. 60 participants.
February 28, 2003. SAFS Project CT Phase: Opportunities and decisions to be made. JPM slide presentation to SAFS Project and LTRAS staff about Conservation Tillage Workgroup equipment and suggestions.
March 6, 2003. Promoting the use of conservation tillage in California. Invited presentation to USDA Natural Resources Conservation Service State Technical Guide Committee. Davis, CA.
March 6, 2003. Conservation tillage initiatives in California. Invited presentation to Community Alliance with Family Farmers and Solano County Farmers. Davis, CA.
March 7, 2003. Conservation tillage initiatives in California. Invited informational presentation at State Senate Hearing Session Chaired by Senator Dean Florez. Bakersfield, CA. 200 participants.

Progress 01/01/02 to 12/31/02

Outputs
Less than 1% of row crop acreage in California is currently farmed using conservation tillage (CT) practices. Adoption of CT systems in California has, however, recently been seen as a potential means for improving profitability and reducing energy use and a number of research, demonstration and evaluation initiatives have recently been started to explore a variety of cropping system options for reducing tillage. In the fall of 1999, we established a 3.2 hectare field experiment comparing conservation and standard tillage (ST) cotton and tomato production systems with and without winter cover crops at the University of California West Side Research and Extension Center in Five Points, CA in terms of 1) farm productivity and profitability, 2) soil quality indicator properties, 3) soil water relations, the quantity and composition of dust produced, and 4) pest and crop management requirements. Current standard production systems for these crops in this region are quite tillage and energy-intensive and virtually no experimental work has been done to evaluate potential alternatives in this critically-important agricultural production valley. To date, this NRI study has demonstrated that planting and harvesting crops with conservation tillage systems is possible given some equipment modifications and that yields can be maintained relatively close to those of standard tillage in CT crop residue environments. Data from the second year of this study indicate that tomato yields in the CT + cover crop systems were similar to those in the standard till plots, with an elimination of six tillage operations following last year's cotton crop in the CT plots relative to the standard till systems. 2001 cotton yields were reduced 11 and 18% in the CT - cover crop and CT + cover crop systems, respectively, relative to the standard tillage control system, however, there was an elimination of 8 or 9 tillage operations in the CT systems relative to the ST approach following the 2000 tomato crop. Estimated resource use per acre (hours of labor and gallons of fuel) indicate the possibility of the CT systems to reduce these inputs relative to the standard till systems. Dust production associated with the various tillage operations that were used in each production system was lower in both the CT systems relative to the standard tillage systems. This study is the first of its kind in California to systematically compare tillage system alternatives through a crop rotation. Longer-term implications of these reduced till regimes in terms of soil compaction, water use, profitability, soil carbon sequestration, insects and diseases are being evaluated as the study progresses through a four-year cycle.

Impacts
This project is the first to evaluate tillage system alternatives in California's Central Valley in a comprehensive way. It seeks to provide full cost accounting of potential economic and environmental benefits of cropping systems alternatives which are gaining considerable interest, but for which we currently have little experimental or comparative information.

Publications

Mitchell, J.P. 2001. Reducing tillage in tomato rotations: A Progress Report Article Submitted to Californai Tomato Grower's Association Magazine.
Mitchell, J.P. 2002. Conservation tillage tomato and cotton production systems in California. Proceedings 25th Southern Conservation Tillage Conference. Pp. 59 - 61. Making Conservation Tillage Conventional: Building a Future on 25 Years of Research. Auburn, AL.
Mitchell, J.P. 2002. Reduced tillage production alternatives for processing tomatoes and cotton in California's San Joaquin Valley. Abstract and poster paper. XXVth International Horticultural Congress and Exhilbition (IHC 2002). Horticulture: Art and Science for Life. Toronto, CANADA. P. 278 of On-site proceedings.

Progress 01/01/01 to 12/31/01

Outputs
Less than 1% of row crop acreage in California is currently farmed using conservation tillage (CT) practices. Adoption of CT systems in California has, however, recently been seen as a potential means for improving profitability and reducing energy use and a number of research, demonstration and evaluation initiatives have recently been started to explore a variety of cropping system options for reducing tillage. In the fall of 1999, we established a 3.2 hectare field experiment comparing conservation and standard tillage (ST) cotton and tomato production systems with and without winter cover crops at the University of California West Side Research and Extension Center in Five Points, CA in terms of 1) farm productivity and profitability, 2) soil quality indicator properties, 3) soil water relations, the quantity and composition of dust produced, and 4) pest and crop management requirements. Current standard production systems for these crops in this region are quite tillage and energy-intensive and virtually no experimental work has been done to evaluate potential alternatives in this critically-important agricultural production valley. To date, this NRI study has demonstrated that planting and harvesting crops with conservation tillage systems is possible given some equipment modifications and that yields can be maintained relatively close to those of standard tillage in CT crop residue environments. Data from the second year of this study indicate that tomato yields in the CT + cover crop systems were similar to those in the standard till plots, with an elimination of six tillage operations following last year's cotton crop in the CT plots relative to the standard till systems. 2001 cotton yields were reduced 11 and 18% in the CT - cover crop and CT + cover crop systems, respectively, relative to the standard tillage control system, however, there was an elimination of 8 or 9 tillage operations in the CT systems relative to the ST approach following the 2000 tomato crop. Estimated resource use per acre (hours of labor and gallons of fuel) indicate the possibility of the CT systems to reduce these inputs relative to the standard till systems. Dust production associated with the various tillage operations that were used in each production system was lower in both the CT systems relative to the standard tillage systems. This study is the first of its kind in California to systematically compare tillage system alternatives through a crop rotation. Longer-term implications of these reduced till regimes in terms of soil compaction, water use, profitability, soil carbon sequestration, insects and diseases are being evaluated as the study progresses through a four-year cycle.

Impacts
This project is the first to evaluate tillage system alternatives in California's Central Valley in a comprehensive way. It seeks to provide full cost accounting of potential economic and environmental benefits of cropping systems alternatives which are gaining considerable interest, but for which we currently have little experimental or comparative information.

Publications

No publications reported this period

Progress 01/01/00 to 12/31/00

Outputs
This research project, which was initiated in October 1999, is comparing reduced tillage and conventional tillage systems with and without off-season cover crops in a cotton - tomato rotation in California's San Joaquin Valley (SJV) in terms of 1) farm productivity and profitability, 2) soil quality indicator properties, 3) soil water relations, the quantity and composition of dust produced, and 4) pest and crop management requirements. Current standard production systems for these crops in this region are quite tillage and energy-intensive and virtually no experimental work has been done to evaluate potential alternatives in this critically-important agricultural production valley. A cover crop mixture of ryegrain/triticale/vetch was seeded in standard and conservation tillage plots in October 1999 to compare these plots with standard and conservation tillage without winter cover crops. The entire experimental field is 8 acres, which permits four replications of each system with both tomato and cotton plots in each of its 4 years, as well as sufficient implement turning buffer areas for the standard tillage plots. A set of management principles that determine each tillage operation was developed for each system at the start of the study. Because reduced tillage practices have not been used in this area, an important prerequisite for each new phase of this work has been the acquisition and modification of suitable equipment that will permit credible comparisons. In spring 2000, the cover crop in the standard tillage with cover crop system was mowed and disked into the soil as a green manure prior to reforming beds for cotton planting and tomato transplanting. The cover crop in the conservation tillage systems was mowed, sprayed with herbicide and left on the soil surface as a residue mulch. Cotton planting was done using a John Deere 1730 no-till seeder and tomatoes were transplanted using a modified Subsurface Tiller Transplanter. Weed management in the conventional tillage tomato plots was accomplished using a high residue Buffalo cultivator and a combination of preplant herbicide and standard cultivation in the standard tillage plots. The weed management strategies for cotton consisted of preplant herbicide and standard cultivation in the conventional tillage systems and over the top herbicide and herbicide-resistant cotton in the conservation tillage system. Early season tomato plant growth was slowest in the conservation tillage with surface mulch cover crops relative to the three other systems presumably due to lower above and below mulch temperatures. At harvest, tomato yields were highest in the standard and conservation tillage systems without cover crops, and reduced by about 5 and 10% in the standard tillage and conservation tillage systems with cover crops, respectively. However, yields in all 4 systems were more than 50 tons/acre, which is over 20% higher than the average yields of SJV processing tomato producing counties. Production costs and dust generation of all operations associated with each system have also been monitored throughout the study's first year.

Impacts
This project is the first to evaluate tillage system alternatives in California's Central Valley in a comprehensive way. It seeks to provide full cost accounting of potential economic and environmental benefits of cropping systems alternatives which are gaining considerable interest, but for which we currently have little experimental or comparative information.

Publications

MITCHELL, J.P. 2000. Conservation tillage production systems in the San Joaquin Valley. Annual Report of the University of California West Side Research and Extension Cente