ORGANIC WEED MANAGEMENT SYSTEMS FOR MISSOURI

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: OTHER GRANTS
• Reporting Frequency: Annual
• Accession No.: 1004003
• Grant No.: 2014-51300-22251
• Cumulative Award Amt.: $922,889.00
• Proposal No.: 2014-05341
• Project Start Date: Sep 1, 2014
• Project End Date: Aug 31, 2019
• Grant Year: 2014
• Program Code: [113.A]- Organic Agriculture Research & Extension Initiative

Recipient Organization
UNIVERSITY OF MISSOURI
(N/A)
COLUMBIA,MO 65211

Performing Department
Bradford Farm

Non Technical Summary
This project will improve the competitiveness of organic crop producers in Missouri by providing research and extension in organic weed management systems. Of special interest are the weeds water hemp (Amaranthus rudis) and Palmer amaranth (Amaranthus palmeri).Research and extension outreach will be done in collaboration between the University of Missouri-Columbia, Cooperative Extension and the USDA-ARS. We will study weed management in organic row crop systems utilizing crop rotation, no-till practices, cover crops, and mechanical and thermal between-row control. The novel weed control methods of between-row mowing and mechanical weed pulling will be investigated. Specific goals of the study are to 1) develop management systems to prevent weeds in organic systems, 2) integrate direct weed control measures into a system that begins with prevention, 3) Determine best management practices for cover crop desiccation and cover crop integration into corn-soybean rotations, 4) create extension programs for dissemination of information, and 5) compare economics of different management systems. Outcomes of this research include identification of alternative practices for weed control that will eliminate or reduce soil tillage in organic grain crop systems. Outreach will be through field days, grower meetings, conferences, and written materials. Because weeds are one of the greatest yield-limiting factors in organic production, development of effective integrated crop production and weed management systems will significantly impact organic production systems through improvement of crop yield and farm profit.

Animal Health Component

90%

Research Effort Categories

Basic

10%

Applied

90%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
213	1820	1140	100%

Knowledge Area
213 - Weeds Affecting Plants;

Subject Of Investigation
1820 - Soybean;

Field Of Science
1140 - Weed science;

Keywords

organic

cover

crop

weed

control

flaming

between

row

mowing

puller

mechanical

cultural

rotation

Goals / Objectives
The overall goal of this research project is to improve the competitiveness of organic crop producers in Missouri by providing research into organic management systems that will provide methods to prevent weeds and to treat post-plant weed emergence. In this research, the effects of crop rotation, tillage practices, and allelopathic and weed smothering cover crop mixes will be examined. Approaches will include directed applications of mechanical and thermal post-emergence weed control.This research will be a collaborative effort among faculty and staff at the University of Missouri, Missouri Cooperative Extension, the USDA-Agricultural Research Service (ARS) and stakeholders (organic growers). Results will include demonstrations of proven weed control practices that organic growers can integrate into their production practices. Also, this collaborative effort will serve to identify the University of Missouri as a knowledge resource for stakeholders. Specific goals of the study are to:Develop management systems to prevent weeds in organic grain/oilseed production systemsIntegrate direct weed control measures into a system that starts with preventionDetermine best management practices for cover crop desiccation and cover crop integration into corn-soybean rotationsCreate and expand extension programs for dissemination of informationCompare economics of different management and weed control systems

Project Methods
Goal 1. Develop management systems to prevent weeds in organic systems We will use two crop rotations in this study. These will be 1) winter cover crop (WCC) soybean-winter wheat/double crop soybean- WCC-corn and 2) WCC-soybean-winter wheat/summer cover crop- WCC- corn. The difference between these two rotations is the use of a summer cover crop instead of double cropping soybeans after wheat in rotation two. Soybeans following wheat in Missouri often do not yield well and contribute little to improved soil health. A summer cover crop will not only help smother out summer annual weeds and shrink the weed seed bank, but it will also add organic matter, which eventually leads to healthier soil more capable of absorbing and holding plant available water. The summer cover crop followed by a winter cover crop will also add nitrogen to the soil through legume N2 fixation that will become available to the corn crop the following year. An economic evaluation of these two cropping rotations will be undertaken as well.In our study, we will utilize a cover crop polyculture that mixes species with varying rooting depths, different plant groups and a range of life cycles. This mixture will include oats (Avena sativa), cereal rye, hairy vetch, crimson clover (Trifolium incarnatum), Austrian winter pea (Pisum sativum subsp. Arvense) and canola (Brassica napus). The legumes in this mix will provide nitrogen, the rye will provide weed control and all component species will contribute to increased soil organic matter (SOM) levels.To compare weed control and soil quality in organic no-till versus organic till, the cover crop will either be mowed and tilled under or it will be crimped and left as a surface mulch for no-till. Goal two describes the weed control that will be implemented under each tillage system.Goal 2. Integrate direct weed control measures into a system that starts with prevention Because cultural prevention treatments cannot be expected to control all weeds at all times, other measures must also be considered for season-long weed management. In this experiment (table 1), the traditional method of weed control in organic systems using rotary hoeing and between-row cultivation will be compared to flaming in tilled plots and hot water spray, between-row mowing or mechanical weed pulling in no-till plots.If flame weeding is used in no-till organic production, the flames could start fires in the desiccated cover crop mulch. Therefore, treatment with hot water spray and between-row mowing in no-till plots will be used as post-emergent weed control. A hot water pressure washer with a diesel powered burner will be modified to enable application of water at a temperature of up to 88ºC. The hot water sprayer will be tractor mounted and the spray stream will be hooded to protect crop plants from damage. Pressure will be set to 50 psi through pump modification.Between-row mowing in no-till fields is a weed control method that was pioneered at the University of Missouri in the mid-1990s. USDA-ARS researchers utilized banded herbicide application and between-row mowing to reduce herbicide use in a non-organic system. Although it was never successfully adopted by non-organic growers, it could be a useful weed control practice in an organic system. In a two-year study (Donald et al., 2001), total grass and broadleaf cover was the same for mowed treatments as the weed-free check and corn and soybean yields were not affected by mowing. In a second study (Donald, 2007), between-row mowing controlled and reduced annual weed cover as well as applications of atrazine and s-metolachlor.A mechanical weed puller is commercially available but little to no replicated research has been done on its ability to effectively control weeds in an organic system. The weed puller utilizes hydraulically driven rollers to grasp weeds and pull them out of the ground. It is unknown how application of a weed puller will affect yields, if it will cause crop damage and if it will be effective at removing weeds in different moisture conditions. However, because it causes much less soil disturbance compared to cultivation and is feasible to be used in conjunction with organic no-till, this could be a viable method of post-emerge weed control for organic producers.Goal 3. Determine best management practices for cover crop desiccation and cover crop integration into a corn-soybean rotationTo determine the effects of shorter season cash crops and delayed corn planting in the spring we will conduct two experiments. In experiment one (table 2), the winter cover crop will be desiccated at anthesis by crimping and 90-day, 105-day and 115-day corn will be planted and yields and economic impacts of the treatments will be evaluated. In addition, soybeans with relative maturities (RM) of 3.5, 3.9 and 4.3 will be compared. In central Missouri, 115-day corn and 4.3 RM soybeans are commonly grown. Post-emerge weed control will be between-row mowing.In experiment two (table 3), the cover crop will be mowed at four different dates (April 15, May 1, May 15, May 30) and for each date 90, 105 and 115-day corn will be grown. This will be conducted under tilled conditions because we do not expect that a cover crop destroyed on April 15 or May 1 will have reached reproductive stages and be conducive to crimping and organic no-till. The end of April is considered the ideal planting date for corn in central Missouri. If delaying corn planting to mid or late May does not significantly affect yields and profits, this information could help improve adoption of cover crops and organic no-till methods. Emerged weeds will be managed using cultivation.Goal 5. Compare economics of different management systems As an integral part of organic research, producers need applied information on the economics of the different weed management systems. As part of this research, ongoing data collection on all aspects of direct and indirect input costs for each type of comparative production technique will be collected. Upon harvest, yields and appropriate market prices will also be collected. The data collected on the costs and benefits of each production technique will serve as a basis for comparison of economic viability. All crops in this study are organic, so the economics will be based on relative benefits and costs between management practices. In addition, sensitivity analysis will be conducted to analyze how sensitive net profits are to different variables in each production system.The research data collected on input costs and returns will provide a basis for the development of an organic production budget in Missouri for use by Missouri producers. The annual organic enterprise budgets will take the multi-year impacts and alternative uses, as well as the direct and indirect production costs, and annualize them for use by organic producers in decision-making.

Progress 09/01/14 to 08/31/19

Outputs
Target Audience:We have successfully reached our target audiences of lower Midwest organic growers and those interested in organic production, agricultural professionals, and students. These students are young people who may go on to become farmers, researchers, agri-business owners, policy makers, and agricultural program support staff. Through participation in national and regional conferences, such as MOSES, the American Society of Agronomy, the American Society of Agricultural and Biological Engineers, the North Central Weed Science Society and SARE, we have reached a target audience of agricultural researchers, farmers, policy makers, and students. Changes/Problems:Extremely high rainfall in spring and summer of 2015 forced us to take the cover crop to maturity then mow and disk before planting cash crops. This removed the primary weed control system (cover crop mulch) from many treatments. Secondary treatments were still followed but were not effective without a cover crop mulch. Due to a design error, our weed puller had to be returned to the manufacturer and was dropped from the experiment in 2016. Flaming in soybeans was dropped in 2016 due to the difficulty in achieving adequate weed control without burning all the soybean plants. In 2018, the hot water sprayer was not utilized in the research due to an engine problem that could not be fixed in a timely manner. Additionally, weed growth in soybean plots was extensive in 2018 and as a result, weeds made all treatments except for the between-row mowing un-harvestable. This includes the double crop soybeans. What opportunities for training and professional development has the project provided?Graduate research and extension training was conducted for four students under this project, two in plant science, one in soil science and one in agricultural engineering Kerry Clark, Ricardo Silva Costa, and Jill Staples all attended the American Society of Agronomy meetings to learn about new research in organic production from 2015-2018. Betzabet Valdez attended in 2018. Reid Smeda and Ricardo Costa Silva participated in the 2015-2018 North Central Weed Science Society Meetings while Betzabet Valdez participated in the meeting from 2018-2019. Gabriel Abdulai participated in professional development by attending the American Society of Agricultural and Biological Engineers Association annual meetings in 2016-2017. Ricardo Costa Silva attended the MOSES Organic Conference in 2016 and Betzabet Valdez attended in 2018. All project staff and students also attended the Midwest Organic Conference annually from 2015-2018. How have the results been disseminated to communities of interest? An organic field day was hosted on August 6, 2015 and attended by approximately 200 organic growers, and Extension and NRCS professionals. 25 fifteen-minute presentations on organic production were attended by 2000 high school students at the MU Ag Education Field Day in 2015. An Organic field day was held at the Bradford Research Center on August 10, 2016 and was attended by 85 people. Kerry Clark gave a one-hour presentation on organic research to approximately 50 people at the Mid-America Organic Association Conference in Springfield, MO on February 6, 2016. We also had an informational booth at the MOA Conference that reached up to 600 participants. A demonstration on erosion and cover crops was attended by 2000 high school students at the MU Ag Education Field Day in 2016. Two presentations were given at the American Society of Agronomy and the North Central Weed Science Society conferences in 2016. A research poster was presented at the MOSES conference in LaCrosse WI in 2017. We gave presentations on organic no-till and had an exhibitors table at the Mid-America Organic Conference in 2017 Two on-farm field days were held in 2017 at Arrow Rock and Hermann, MO that were attended by 120 and 45 people, respectively. Both focused on mowing in organic no-till. On September 6, 2017 we presented 22 fifteen-minute talks on organic production to 2000 Missouri high school students at the MU Agricultural Education Field Day. Presentations on our research results were given at the American Society of Agronomy and the North Central Weed Science Society conferences in 2017. In 2017, we provided information on MU research activities and conducted a survey by mail of the approximately 700 certified organic farming and agribusiness operations in Missouri to determine the effects of our research and outreach and to assess needs of the Missouri organic community On January 24-26, 2018, we had a booth at the Mid-America Organic Conference in Kansas City, MO and presented information on organic no-till and organic weed control. The event was attended by 600 Midwest organic growers and other interested parties such as Extension and NRCS. On July 29, 2018 we held a field day on Organic Transitioning in Poplar Bluff, MO on an organic farm owned by Don Delozier and co-hosted by Midwest BioAG and Pipeline Foods that was attended by 20 area farmers. This part of Missouri (Mississippi River delta) is traditionally low in organic production but due to its high productivity, buyers are interested in recruiting organic farmers from the area. A major topic of discussion ended up being the difficulty of organic and non-GMO soybean production in the area due to the large scale of dicamba damage experienced by all farmers not growing dicamba resistant soybeans. A second field day was held August 29, 2018 in Nelson MO on an organic farm owned by Derek Davis and co-hosted by River Valley Ag Exchange, an organic elevator and farm supply company located in Marshal, MO. Attended by 120 farmers, this field day was focused on organic weed control and Gary McDonald was the primary speaker. Gary detailed soil health and cultivation methods for a full day. We also had equipment demonstrations, including a Weed-Zapper, which kills weeds with electrical current, and the University of Missouri between-row mower. Presentations on our research results were given at the American Society of Agronomy and the North Central Weed Science Society conferences in 2018. On April 5, 2018, Kerry Clark presented our field research to 60 farmers and scientists at the SARE Our Farms, Our Future National Conference. On September 4, 2018 we presented 15 fifteen-minute talks on organic production to 2000 Missouri high school students at the MU Agricultural Education Field Day. We continue to reach Missouri farmers through our research center website at https://bradford.missouri.edu What do you plan to do during the next reporting period to accomplish the goals?Nothing

Impacts
What was accomplished under these goals? Soil quality in the U.S. is severely impacted by agricultural practices that lead to erosion, loss of soil organic matter, and reduced ability of soil to absorb water for plant growth. Excessive use of tillage and the lack of growing plants for much of the year lead to reduced soil quality. Organic production can contribute to soil degradation because of its reliance on multiple tillage events for weed control. This research project has shown that organic producers can utilize cover crops and between- row mowing for weed control that is as effective as tillage and cultivation. This project has designed tools that can be used by producers for weed control that does not disturb soil or cause loss of soil function. These tools can be commercialized by local industries for adoption by all growers interested in conserving soil quality. This research has given organic farmers increased tools to fight weeds while lessening their negative impact on soil quality. This will lead to improved profits and improved production sustainability. Specific goals of the study included the following areas. Develop management systems to prevent weeds in organic grain/oilseed production systems and integrate direct weed control measures into a system that starts with prevention. Production systems in corn and soybean utilizing tillage and cultivation or flaming for weed control were compared to systems that used no-till and cover crops with hot water or mowing applications for secondary weed control. Weed biomass and crop yield were collected for four years. To accomplish this experiment, a between-row mower and a hot water sprayer were built in year one, with improvements made in years 2-4. Data collected in this experiment demonstrates that yields were not adversely affected by mowing, except for a slight yield decrease in soybean in 2017. In 2017, corn yields were highest where a crimped cover crop was utilized. This shows that alternative weed control to cultivation can be used in organic production to reduce soil disturbance. Key outcomes of this objective included increased knowledge of the effect on yield and weed control of four different types of organic weed control. This is the first experiment in organic production using these two novel types of weed control (mowing and hot water) so our results will help steer future research and exploration into the equipment and methods used. Our outreach exposed many people to these new ideas and farmers in Missouri have expressed an interest in developing or procuring mowing equipment. This can lead to changes in practices that will conserve soil quality and can also lead to new business development for manufacturers of the equipment developed and used in this research. We also have reached out to two commercial manufacturers who are prototyping crop mowers and we are working directly with a NC-SARE Farmer/Rancher grant recipient who built a two-row between-row mower. We assisted him with designs and experimentation. Ancillary experiments with the hot water sprayer have established the necessary amount of time and volume of water that must be utilized to achieve adequate weed control. Determine best management practices for cover crop desiccation and cover crop integration into corn-soybean rotations Two experiments were conducted to address this objective. In one trial, three different corn maturities (95, 105 and 115 days) were planted at four different spring dates including mid-April, late-April, mid-May and late-May. The objective of this was to determine if organic producers can feasibly alter recommended planting dates and variety maturities to better fit cover crops into production system. In addition to crop yield, soil and leaf samples were collected to quantify the amount of nitrogen contributed by the cover crops at each planting date. In a second experiment, grain yield was assessed with these same three corn maturities and three soybean maturities (3.5, 3.9, 4.3), which were planted immediately after a rye cover crop reached anthesis. The purpose was to determine effects of crop relative maturity in an organic no-till system. We determined that cover crop growth and weed control are improved when organic fertilizer is added before cover crop planting, rather than prior to crop planting This still leads to excellent cash crop productivity We determined that when incorporating a cover crop into the soil, the cover crop must be destroyed and incorporated at least seven days prior to crop planting to reduce seed to soil contact interference from the cover crop residue Soybean has excellent emergence in the cover crop but corn emergence is greatly inhibited and early corn growth is affected by N tie-up in the crimped cover crop. Supplemental N had to be added to the corn in organic no-till treatments. A comparison of planting date and corn maturity shows that corn maturity has greater effect on yields than does planting date, which may lead to recommendations that allow greater cover crop growth in the spring. Soybean maturity has less effect on yield than does corn maturity. Create and expand extension programs for dissemination of information. We have conducted Organic Field Days at the MU Bradford Research Center for many years, but in 2017 started to have shorter, more geographically available field days at cooperating farmers. We continued this format in 2018-2019 with great success. This has not only led to a more engaged and interested audience, but it has also allowed us to help build the capacity of local business and farmers to host field days. We began collaborations with multiple seed and input provision companies in the Midwest region to co-host field days as well. We have also spoken at national conferences to increase exposure to our novel weed control methods and to encourage other programs or researchers to investigate improving on our methods. Our extension efforts reached several thousand people from 2015-2019.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Kerry Clark, Ricardo Costa-Silva. 2016. Timing of corn planting in organic no-till. Conference Proceedings of the American Society of Agronomy. https://scisoc.confex.com/scisoc/2016am/webprogram/Paper99361.html
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Gabriel A.Z. Abdulai, J. Benton Naylor, Ricardo Costa Silva, Reid J. Smeda and Kerry M. Clark. Mechanical Weed Control Using Mowing in Organic No-till. ASA Symposium--Engineering Solutions and New Machines for Organic Agriculture. October 23, 2017. Tampa FL
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Gabriel A.Z. Abdulai, J. Benton Naylor and Kerry M. Clark. 2017. Between-row mower for organic weed control. ASABE Conference. Spokane, Washington July 16 - July 19, 2017.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Jill Staples, Kerry M. Clark, MO, Robert J. Kremer, Kimberly Griffin and Kristen Sloan Veum. Soil Health Response to Thermal Weed Management in an Organic System. ASA General Organic Management Systems Poster. Tuesday, October 24, 2017. Tampa, FL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Ricardo Costa Silva, Kerry M. Clark and Reid J. Smeda. Mechanical and Thermal Weed Control in Organic Tilled and No- till Production. ASA General Organic Management Systems Oral I. Tuesday, October 24, 2017. Tampa, FL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Staples, J., K. Griffin, K. Clark, R.J. Kremer. Soil Health Response to Alternative Cultivation Practices in an Organic System. 2019. Soil Science Society of America International Soils Meeting. San Diego, CA Jan 6-9, 2019.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Clark, K.M. 2018. Mowing for Organic Weed Control. American Society Agronomy Conference. November 4-7, 2018. Baltimore, MD
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Valdez, Betzabet, Kerry Clark and Reid J. Smeda. Postemergence Herbicides for Weed Control in Organic Corn and Soybeans. 2018. American Society of Agronomy Conference. November 4-7, 2018. Baltimore, MD
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Costa-Silva, Ricardo and Reid Smeda. Organic Weed Control. North central Weed Science Society of America Annual Conference.10/07/2015. Indianapolis, IN.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Clark, Kerry, Ricardo Costa-Silva and Reid Smeda. Organic No-Till. Midwest Organic Association Annual Conference. 02/06/2016. Springfield, MO
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Costa-Silva, Ricardo. 2018. Mechanical and Thermal Weed Control In Organic Crops. https://mospace.umsystem.edu/xmlui/handle/10355/63464
• Type: Theses/Dissertations Status: Published Year Published: 2018 Citation: Gabriel Abdulai. 2018. Between-Row Mower Design for Weed Control in Organic No-Till Soybeans. https://mospace.umsystem.edu/xmlui/handle/10355/66311
• Type: Theses/Dissertations Status: Published Year Published: 2017 Citation: Souliere Staples, J.E., 2017. Soil quality assessment for an alfisol undergoing alternative organic weed management systems. https://mospace.umsystem.edu/xmlui/handle/10355/63385
• Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2019 Citation: Valdez, Betzabet. 2019. Weed Control in Organic Agricultural Systems.

Progress 09/01/17 to 08/31/18

Outputs
Target Audience:Our extension efforts reached approximately 140 organic and transitioning farmers at summer field days and another 500 growers, agricultural professionals and government staff at the Mid-America Organic conference. We reached approximately 120 researchers and students from around the nation at the 2017 American Society of Agronomy Conference and an additional 60 researchers, farmers, and governmental staff from US programs at the SARE conference. We also reached 2200 high school students in Missouri. Changes/Problems:In 2018, the hot water sprayer was not utilized in the research due to an engine problem that could not be fixed in a timely manner. Additionally, weed growth in soybean plots was extensive in 2018 and as a result, weeds made all treatments except for the between-row mowing unharvestable. This includes the double crop soybeans. What opportunities for training and professional development has the project provided?Kerry Clark, Ricardo Silva Costa, and Jill Staples all attended the 2017 American Society of Agronomy meetings to learn about new research in organic production. Reid Smeda and Ricardo Costa Silva participated in the North Central Weed Science Society Meetings. Gabriel Abdulai participated in professional development by attending the American Society of Agricultural and Biological Engineers Association annual meetings. How have the results been disseminated to communities of interest?On July 29, 2018 we held a field day on Organic Transitioning in Poplar Bluff, MO on an organic farm owned by Don Delozier and co-hosted by Midwest BioAG and Pipeline Foods that was attended by 20 area farmers. This part of Missouri (Mississippi River delta) is traditionally low in organic production but due to its high productivity, buyers are interested in recruiting organic farmers from the area. A major topic of discussion ended up being the difficulty of organic and non-GMO soybean production in the area due to the large scale of dicamba damage experienced by all farmers not growing dicamba resistant soybeans. A second field day was held August 29, 2018 in Arrow Rock, MO on an organic farm owned by Derek Davis and co-hosted by River Valley Ag Exchange, an organic elevator and farm supply company located in Marshal, MO. Attended by 120 farmers, this field day was focused on organic weed control and Gary McDonald was the primary speaker. Gary detailed soil health and cultivation methods for a full day. We also had equipment demonstrations, including a Weed-Zapper, which kills weeds with electrical current, and the University of Missouri between-row mower. On January 24-26, 2018, we had a booth at the Mid-America Organic Conference in Kansas City, MO and presented information on organic no-till and organic weed control. The event was attended by 600 midwest organic growers and other interested parties such as Extension and NRCS. On April 5, 2018, Kerry Clark presented our field research to 60 farmers and scientists at the SARE Our Farms, Our Future National Conference. October 22-25, 2017, Kerry Clark and Ricardo Costa presented two oral presentations at the Organic Community forum at the American Society of Agronomy Conference in Tampa, Fl. On September 6, 2017 we presented 22 fifteen minute talks on organic production to 22 Missouri high school students. We continue to reach Missouri farmers through our research center website at https://bradford.missouri.edu What do you plan to do during the next reporting period to accomplish the goals? Collect and analyze final soil samples for soil health indicators Conduct final crop harvest and analyze yield data Analyze final weed biomass and density data Analyze and summarize economic data Prepare manuscripts for publication on: Engineering of between-row mower Engineering of hot water sprayer Weed biomass, species, and density in organic production using mechanical and thermal weed control methods Effect of planting date and variety maturity on organic corn yield Organic corn and soybean yields by variety maturity following production of a cover crop to anthesis. Soil Quality under mechanical and thermal weed control methods in organic production MS student in Plant Science will finish coursework and thesis and graduate in May, 2019

Impacts
What was accomplished under these goals? Soil quality in the U.S. is severely impacted by agricultural practices that lead to erosion, loss of soil organic matter, and reduced ability of soil to absorb water for plant growth. Excessive use of tillage and the lack of growing plants for much of the year lead to reduced soil quality. Organic production can contribute to soil degradation because of its reliance on multiple tillage events for weed control. This research project has shown that organic producers can utilize cover crops and between-row mowing for weed control that is as effective as tillage and cultivation. This project has designed tools that can be used by producers for weed control that does not disturb soil or cause loss of soil function. These tools can be commercialized by local industries for adoption by all growers interested in conserving soil quality. This research has given organic farmers increased tools to fight weeds while lessening their negative impact on soil quality. This will lead to improved profits and improved production sustainability. Specific goals of the study included the following areas. Develop management systems to prevent weeds in organic grain/oilseed production systems and integrate direct weed control measures into a system that starts with prevention. Production systems in corn and soybean utilizing tillage and cultivation or flaming for weed control were compared to systems that used no-till and cover crops with hot water or mowing applications for secondary weed control. Weed biomass and crop yield were collected for four years and will be completed in October, 2018. To accomplish this experiment, a between-row mower and a hot water sprayer were built in year one, with improvements made in years 2-4. Data collected in this experiment demonstrates that yields were not adversely affected by mowing, except for a slight yield decrease in soybean in 2017. In 2017, corn yields were highest where a crimped cover crop was utilized. This shows that alternative weed control to cultivation can be used in organic production to reduce soil disturbance. Key outcomes of this objective included increased knowledge of the effect on yield and weed control of four different types of organic weed control. This is the first experiment in organic production using these two novel types of weed control (mowing and hot water) so our results will help steer future research and exploration into the equipment and methods used. Our outreach exposed many people to these new ideas and several farmers in Missouri have expressed an interest in developing or procuring mowing equipment. This can lead to changes in practices that will conserve soil quality and can also lead too new business development for manufacturers of the equipment developed and used in this research. We also have reached out to two commercial manufacturers who are prototyping crop mowers and we are working directly with a NC-SARE Farmer/Rancher grant recipient who is building a two-row between-row mower. We have assisted him with designs and experimentation. Determine best management practices for cover crop desiccation and cover crop integration into corn-soybean rotations Two experiments were conducted to address this objective. In one trial, three different corn maturities (95, 105 and 115 days) were planted at four different spring dates including mid-April, late-April, mid-May and late-May. The objective of this was to determine if organic producers can feasibly alter recommended planting dates and variety maturities to better fit cover crops into production system. In addition to crop yield, soil and leaf samples were collected to quantify the amount of nitrogen contributed by the cover crops at each planting date. In a second experiment, grain yield was assessed with these same three corn maturities and three soybean maturities (3.5, 3.9, 4.3), which were planted immediately after a rye cover crop reached anthesis. The purpose was to determine effects of crop relative maturity in an organic no-till system. Data is still being analyzed in these two experiments. Create and expand extension programs for dissemination of information. In year 3 or this grant, we switched from research station field days to on-farm field days. We continued this format in 2018 with great success. This has not only led to a more engaged and interested audience, but it has also allowed us to help build the capacity of local business and farmers to host field days. We have also spoken at national conferences to increase exposure to our novel weed control methods and to encourage other programs or researchers to investigate improving on our methods. Our extension efforts reached several thousand people in 2018. Compare economics of different management and weed control systems Economic data has been collected but has not yet been fully analyzed.

Publications

• Type: Theses/Dissertations Status: Accepted Year Published: 2018 Citation: Costa-Silva, Ricardo. 2018. Mechanical and Thermal Weed Control In organic Crops.https://mospace.umsystem.edu/xmlui/bitstream/handle/10355/63464/research.pdf?sequence=2&isAllowed=y
• Type: Theses/Dissertations Status: Awaiting Publication Year Published: 2018 Citation: Gabriel Abdulai. MS Thesis. University of Missouri. August 2018. Between-Row Mower Design for Weed Control in Organic No-Till Soybeans. Has not yet been published to mospace.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Gabriel A.Z. Abdulai, J. Benton Naylor, Ricardo Costa Silva, Reid J. Smeda and Kerry M. Clark. Mechanical Weed Control Using Mowing in Organic No-till. ASA Symposium--Engineering Solutions and New Machines for Organic Agriculture. October 23, 2017: 2:35 PM. Tampa FL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Ricardo Costa Silva, Kerry M. Clark and Reid J. Smeda. Mechanical and Thermal Weed Control in Organic Tilled and No-till Production. ASA General Organic Management Systems Oral I. Tuesday, October 24, 2017. Tampa, FL.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Jill Staples, Kerry M. Clark, MO, Robert J. Kremer, Kimberly Griffin and Kristen Sloan Veum. Soil Health Response to Thermal Weed Management in an Organic System. ASA General Organic Management Systems Poster. Tuesday, October 24, 2017. Tampa, FL.

Progress 09/01/16 to 08/31/17

Outputs
Target Audience:We reached approximately 150 fellow scientists and graduate students during our presentations at the American Society of Agronomy and the North Central Weed Science Society conferences in 2016. By presenting our research at the MOSES conference in LaCross WI, we reached organic growers from throughout the lower and upper midwest. During presentations at the Mid-America Organic Conference, we reached over 600 organic growers from Missouri, Kansas, Illinois, Arkansas and Oklahoma. In our two on-farm field days, we reached organic growers interested in organic no till and other organic practices from throughout Missouri. Our audience included 200 farmers, NRCS, Extension and Soil and Water District Staff We reached about 1000 high school age students at the MU ag education field day. These are young people who may go on to become farmers, researchers, agri-business owners, policy makers, and agricultural program support staff. Changes/Problems:The economist on our team left the University of Missouri. We will continue to use him as a consultant rather than as a co-PI. What opportunities for training and professional development has the project provided?One graduate student and one faculty member attended the North Central Weed Society Annual Conference One graduate student attended the MOSES Organic Conference One graduate student and one faculty member attended the American Society of Agronomy Annual Conference One graduate student attended the American Society of Agricultural and Biological Engineers Annual Conference How have the results been disseminated to communities of interest?Two presentations at the American Society of Agronomy and the North Central Weed Science Society conferences in 2016. A research poster at the MOSES conference in LaCross WI in 2017. Presentations and an exhibitors table at the Mid-America Organic Conference in 2017 Two on-farm field days in 2017 at Arrow Rock and Hermann, MO Presentations at the MU ag education field day in 2017. We have also begun a revamping of our webpage because the MU organic program moved in 2017 from being under a research center to becoming a seperate and independent entity. The new webpage will become public in early 2018. What do you plan to do during the next reporting period to accomplish the goals?In 2018, we will complete our data collection on weed management systems, best management practices for cover crop dessication and cover crop integration into corn-soybean rotations. We will develop recommendations for farmers and post them on our website and present them at conferences and field days We will finish developing a new webpage with results for organic research at the University of Missouri We will finish production of several videos on production recommendations and post them We will develop and implement new farmer-led field days We will do an economic analysis of the weed treatment systems used in this research project We will start work on publications including: Design of a mower for weed control in row crops; Economic comparisons of four organic weed control systems; Corn maturity ranges that integrate best with cover crops in organic systems; Corn and soybean maturity ranges that integrate with an organic no-till system; Agronomic comparison of four organic weed control systems; Soil health affects of thermal and mechanical weed control in organic systems; Hot water spray for weed control in organic production.

Impacts
What was accomplished under these goals? We are completing the third of four years of research. We are continuing to discern which weed control systems and practices lead to the highest yields in organic systems. Over the past year, we made significant accomplishments in improving two of those systems, organic no-till using post-emerge hot water spray and using post-emerge mowing for weed control. Ancillary experiments with the hot water sprayer have established the necessary amount of time and volume of water that must be utilized to achieve adequate weed control. We developed a tractor-mounted, four-row mower in 2017 that has the potential to be commercialized for use by organic growers. We will continue to improve on this equipment in 2018 We have continued to fine tune management of cover crops in organic no-till and have determined that cover crop growth and weed control are improved when organic fertilizers are added before cover crop planting, rather than prior to crop planting. This still leads to excellent cash crop productivity. We have determined that when incorporating a cover crop into the soil, this cover crop must be destroyed and incorporated at least seven days prior to crop planting to reduce interference from cover crop residue. We held our first on-farm field days in 2017 and greatly increased the number of practicing organic row crop farmers that we reach. These were farmer-led events that we supported with planning, logistics, and publicity. Feedback was excellent and the use of farmer's own stories and experiences was highly praised. We conducted a survey by mail of the approximately 700 certified organic farming and agribusiness operations in Missouri to determine the effects of our research and outreach and to assess needs of the Missouri Organic community.

Publications

• Type: Theses/Dissertations Status: Accepted Year Published: 2017 Citation: Jill Staples. 2017. Soil quality assessment for an alfisol undergoing alternative organic weed management systems https://mospace.umsystem.edu. Thesis has not yet posted to MoSpace.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Kerry Clark, Ricardo Costa-Silva. 2016. Timing of corn planting in organic no-till. Conference Proceedings of the American Society of Agronomy. https://scisoc.confex.com/scisoc/2016am/webprogram/Paper99361.html

Progress 09/01/15 to 08/31/16

Outputs
Target Audience:Our target audience during this period was farmers who are certified organic or those transitioning to organic. We focused on Missourisoybean and corn growers. Changes/Problems:Due to a design error, our weed puller had to be returned to the manufacturer and was dropped from the experiment in year two. It will llikely be added back in in year three while flaming in soybeans is being considered for dropping due to the difficulty in acheiving adequate weed control without burning all the soybean plants. What opportunities for training and professional development has the project provided?An Organic Field Day was held on August 10, 2016 for training Extension and NRCS staff as well as farmers. Kerry Clark, PI, attended the Organic Community meetings of the American Society of Agronomy annual conference in Minneapolis, MN in November, 2015 and the Mid-America Organic Association Conference in February, 2016 in Springfield, MO. Reid Smeda and Ricardo Costa-Silva both attended the North Central Weed Science Society of America annual conference in Indianoplis, IN in 2016. The project is also training one MS student in weed science, one MS student in soil science and in August, brought in a new MS student in Agricultural Engineering. How have the results been disseminated to communities of interest?An Organic field day was held at the Bradford Research Center on August 10, 2016 and was attended by 85 people. Kerry Clark also gave a one-hour presentation on organic research to approximately 50 people at the Mid-America Organic Association Conference in Springfield, MO on February 6, 2016. We also had an informational booth at the MOA Conference that reached up to 600 participants. What do you plan to do during the next reporting period to accomplish the goals?We will continue field research and data collection. We brought in a student in Ag Engineering to design and build a three-point hitch, four-row between-row mower that will make that weed control method more viable. We will conduct additional experiments on this equipment in 2017. We are expanding the hot-water research to a second field study and we are expanding from one research centerfield day to three farm tours in summer, 2017. Over this winter, economic analysis will begin on each treatment and research will be reported at the MOSES organic conference as well as the Mid-America conference. Lab anaysis of soil samples is ongoing over this winter and data will be ready by spring on both soil health and weed control by each treatment. The soil science MS student will graduate in May 2017 and a second weed science MS student will start in the spring of 2017.

Impacts
What was accomplished under these goals? Develop management systems to prevent weeds In 2015, extremely high rainfallled to an inability to utilize a winter cover crop as weed control in these trials. The weather was more cooperative in late 2015 and early 2016 and the use of the cover crop for primary weed control was successful. Research was successfully conducted comparing organic weed control in a tilled system to no-till. Corn and beans were planted into a standing cover crop in the no-till system, which was then crimped to dessicate the residue. We used a cover crop mix of cereal rye, hairy vetch, rape, Austrian winter pea and crimson clover but discovered in the spring that the rape and the hairy vetch provided more problems as weed competition to the cash crop than any benefits they brought to the system. In fall 2016, we seeded only a cereal rye cover crop before soybean and a cereal rye/Austrian winter pea mix before corn. The cover crop prevented weed growth for the beginning month of cash crop growth. Soybean hadexcellentemergence in the cover crop but corn emergence was greatly inhibited and early corn growth was affected by N tie-up in the crimped cover crop. Supplemental N had to be added to the corn in organic no-till treatments. Integrate direct weed control measures into a system that begins with prevention The weed control measures we integrated into the no-till system included between-row mowing and hot water spray, which were compared to between-row cultivation and flaming in conventionally tilled treatments. A weed puller treatment was also in the experimental design but the equipment malfunctioned due to a design issue and was sent to the manufactuer for repairs, but not returned to us until the end of summer. In soybean, between-row mowing over a crimped cover crop provided the highestcrop yield and the best weed control both in-row and between-row. In corn, flaming and cultivation led to the highest yields while between-row mowing provided the best weed control. Yield was more affected by emergence and early growth than it was by weed control in corn. The hot water sprayer proved to be able to kill small weeds in ancillary testing, but when used in the crimped cover crop was not highly effective due to the larger sizeand later growth stageof weeds that emerge through the crimped cover crop. Both cultivation and flaming in soybean led to reduced yields and high numbers of in-row weeds. Determine best management practices for cover crop dessication and cover crop integration into corn-soybean rotations Two experiments were conducted looking at integrating cover crops into crop rotations in organic production. A comparison of planting date and corn maturity is showing that corn maturity has greater effect on yields than does planting date, which may lead to recommendations that allow greater cover crop growth in the spring. Soybean maturity had less effect on yield than did corn maturity in 2016. We are still examining soil and plant tissue data to determine if delaying cover crop dessication in the spring contributes to soil or tissue N levels. Create and expand Extension programs We have conducted Organic Field Days at the MU Bradford Research Center for several years,but in 2016 began to make plans to have shorter, more geographically available field days at cooperating farmers. In fall, 2016, several cooperators planted winetr cover crops that will serve as backdrops for 2017 field days. Most of the work on this goal still llies in the furture as we work on improving our website and producing research-based Extension publications. Compare economics of systems Economic comparison is being started in fall of 2016. Good data has not been available in first two reporting periods to work on this goal.

Publications

• Type: Conference Papers and Presentations Status: Accepted Year Published: 2015 Citation: Costa-Silva, Ricardo and Reid Smeda. Organic Weed Control. North central Weed Science Society of America Annual Conference.10/07/2015. Indianapolis, IN.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Clark, Kerry, Ricardo Costa-Silva and Reid Smeda. Organic No-Till. Midwest Organic Association Annual Conference. 02/06/2016. Springfield, MO

Progress 09/01/14 to 08/31/15

Outputs
Target Audience:The target audience reached during this reporting period was organic row crop and vegetable producres in Missouri and adjoining states. Changes/Problems:Extremely high rainfall in spring and summer of 2015 forced us to take thecover crop to maturity then mow and disk before planting cash crops. This removed theprimary weed control system (cover crop mulch) from many treatments. Secondary treatments were still followed but were not effective without a cover crop mulch. What opportunities for training and professional development has the project provided?An organic field day was held on August 6, 2015 at the Bradford Research Center for training extensionand NRCS staff as well as producers. Graduate training for two students in organic systems management was provided in 2015. How have the results been disseminated to communities of interest?Organic field day held on August 6, 2015 at Bradford Research Center. What do you plan to do during the next reporting period to accomplish the goals?Continue field research and data collection. Provide research reportat the Missouri Organic Association Conference. Conduct a second field day in 2016. Meet with organic advisory board. Begin to develop extension material.Conduct greenhouse research on hot water treatment of weeds.

Impacts
What was accomplished under these goals? Research was initiated in 2015 and graduate students joined the project in spring and summer, 2015. Management systems were put in place to track the effects of weed control systems that include organic no-till, cultivation, hot water spray, flaming, between row mowing and mechanical weed pulling. Data on weed control, crop yield and soil health was collected in thesummer and fall of 2015. In winter 2015, a hot water sprayer was designed and built by project personnel. An organicfield daywas hosted on August 6 and attended by approximately 200 organic growers.

Publications