Mechanical and biological strategies to remove invasive Bermuda grass in preparation for organic vegetable production on raised beds

Mechanical and biological strategies to remove invasive Bermuda grass in preparation for organic vegetable production on raised beds

Summary

We are organic farmers, small beginning farmers located in middle Georgia. We grow certified organic vegetables, fruits, and nuts including eggplants, cucumbers, sweet peppers, squash, kale, collards, sweet potatoes, cantaloupes, watermelons, strawberries, muscadines, blackberries, and pecans on our farm. We, like many other farmers, face serious challenges when trying to grow vegetables in soil infested with invasive weeds such as common Bermuda grass. This challenge becomes more critical on organic farms that have different tools in their toolkit. Generally, invasive weeds are managed by plowing and cultivation. Excessive tillage can burn up soil organic matter, degrade soil structure, increase erosion, and reduce soil biological health. Organic and sustainable ag producers need to consider alternative integrated strategies as possible tools to manage serious perennial weeds like Bermuda grass; examining strategies that also work to improve soil life and soil quality.

Our Southern SARE project involved a field study of two non-chemical strategies for managing heavy common Bermuda grass infestation to prepare for organic vegetable production. To implement the project we established a mechanized cultivation and hand tillage strategy plot (SARE Plot 2) and a biological control strategy plot using correctly planted and managed cover crops to suppress and control the growth of common Bermuda grass (SARE Plot 1). 

Generally, The biological methods intensive cover crop management over two growing seasons gave higher onion and kale yields, however, was slower to totally suppress Bermuda grass and allowed nutsedge to increase. The mechanical management method suppressed both of these weeds effectively and much quicker. The negative responses were poor suppression of annual weeds and lower vegetable yields, lower soil moisture, etc.

As sustainable ag organic farmers one of our primary interests is to suppress perennial invasive weeds while using methods that protect and improve soil quality and soil life. Therefore as we proceeded with this study, we needed to always keep in mind the impact on soil quality and soil life – an important resource for sustainable agriculture farmers.

We concluded that an integrated approach, might provide better results than either one alone.   We suggest that sustainable ag and organic farmers should also consider methods that support building soil health and characteristics that enhance soil life.

The SSARE Producer Grant project gave valuable initial information on which we can build our farm operation and determine the next set of experimental tactics and strategies.

Objectives/Performance Targets

To evaluate two non-chemical strategies (multiple tillage and cover crops) to control and manage heavy Bermuda grass infestations. ?

To consider which method or combination of methods is most beneficial and successful with managing and controlling perennial invasive weeds- while protecting soil life/soil quality and enhancing yields.

Accomplishments/Milestones

The SSARE Producer Grant Project was successfully completed. The 2014-year had extremes in climate (more rain and cold weather) than anticipated which impacted project scheduling and plant growth. 

During the second year we identified and used a low-P, plant based (or mostly plant based with no chicken litter) compost – concentrating compost applications in or near crop rows, using some of the compost in planting holes when setting out transplants – in order to maximize benefits to the crop. Earthworm compost was a good general starter fertilizer and provided benefits to plants and soil.

Based on our soil test reports, our project cooperator suggested that we needed to provide our crops with available N, K, S, boron (B), and possibly magnesium (Mg) over the growing period of our crops to sustain yields in our soils. This was done through compost and small dosages of other amendments rather than total application at any one time. Strawberries and onions were planted instead of kale and onions.

After review of the weed control progress, the producers decided to run two seasons back to back of intensive cover crops during the second year (buckwheat and pearl millet, followed in the fall by iron clay peas and millet) because we could see the benefit to the soil and we saw a success in the control and management of Bermuda grass. The weeds that followed the reduction in Bermuda grass were crabgrass and nutsedge: intensive cover cropping using iron clay peas and millet were grown to control these weeds setting up the back to back cover crop strategy in SARE-1 during year two.

As a result: Both the SARE-1 biological (intensive cover crops, limited tillage) and SARE-2 mechanical (intensive tillage) successfully reduced common Bermuda grass by more than 90%, though the biological approach took about 16 months to do so, while mechanical had achieved it within the first year. This reduction was sufficient to allow production, at least for cool season crops – strawberry, onion, and kale. Repeated tillage of SARE-2 drastically reduced the yellow nutsedge.

The producers’ examination of the cover crop management field suggested that an increase in soil moisture, soil organic matter content and crop vitality. SARE-1 plot yielded, on average, more than twice as much kale as SARE-2 suggesting a cover crop benefit to the vegetable, and perhaps improved N availability from all the cowpea biomass generated. We could see the benefit of using intensive cover crop mixes in our organic crop rotation plan.

Generally, organic farming with intensive cover crop management strategy seemed to build healthy soil while suppressing weeds and increased crop yields. The organic management with mechanical strategy of light multiple tillage seemed to remove weeds but reduced soil health and decreased vegetable crop yield.

How we see it: We would like to assume a long term gain through intensive cover crop management would support soil life, active organic matter, stable organic matter (humus), overall soil health and soil quality–but this can not be fully determined over the course of a two year project. However we gained some sense of less soil stress and soil improvement due to intensive cover crop strategies and organic farming practices. We would suggest that it might be a benefit to utilize intensive cover crops between crop rotations in our organic farming system.

• 2014 SSARE Lola’s Organic Farm

Impacts and Contributions/Outcomes

We are beginning small minority farmers. We have learned so much through our participation in our funded SARE Producer Grant and through sharing information with farmers, on our organic field days, and through larger discussions as speakers at conferences about our SSARE Producer Grant Project.  Following is a list of project outcomes.?

• February 2014 we presented our Southern SARE Producer Grant Project during the Georgia Organic Conference/Jekyll Island, GA. We were able to share our farm challenge and anticipated on-farm impact with farmers and community gardeners having a similar desire to use organic farming strategies/sustainable ag strategies to control perennial invasive weeds while improving soil benefits and yields. Great discussions and public looking forward to the upcoming on-farm field day.
• Generally, in our area of Georgia, farmers do not know much about sustainable ag organic farming systems – our workshop demonstrations, discussions provided important learning experiences; and networking opportunities for Georgia Organics, NRCS and SSARE identifying opportunities for assistance to small, minority farmers, beginning farmers and gardeners interested in improving farm enterprises and learning more about organic sustainable agriculture:
• June 2014 Lola’s Organic Field day Workshop provided information and demonstrations that could help make rural and urban farmers interested in organic sustainable farm tools more successful: The workshop included history and teaching tour about our small farm and organic farming systems, practical information learned about biological and mechanical weed control strategies for invasive weeds/SARE Funded Project, benefits of high tunnel operations and techniques used to meet organic certification standards. NRCS representative addressed the NRCS High Tunnel and other EQIP Organic-Initiatives beneficial to new beginning farmers, seasoned farmer/urban farm communities; Demonstrations included establishing native pollinator habitats, grafting and pruning, SSARE Project controlling invasive weeds,  and high tunnel.
• The SSARE Producer Grant project at 2014 Lola’s Organic Farm Field Day provided the basis for group examination of different weed management strategies and benefits to an organic sustainable agriculture system.   About seventy people came to the workshop. The participants included rural and urban farmers, locals and consumers. Participants were able to learn from hands-on demonstrations and discussions.
• The June 2014 Lola’s Organic Farm Field Day collaborators included: NRCS Regional Director and NRCS-Wheeler County Office (Ms. Vontice Jackson and Leslie Woodard, respectively), Georgia Organics (Donn Cooper), Fort Valley University (Retired Extensionist/Jerry Larson,) Longwood Plantation (Karen and Mike Smith), and Lola’s Organic Farm SSARE Project Producers Ron Gilmore and Jennifer Taylor.

 June 2014 Registration information:

http://georgiaorganics.org/goevent/organic-production-workshop-lolas-organic-farm/?utm_source=MASTER+EMAIL+LIST&utm_campaign=d1a9bafbc9-June_2014_eDirt6_3_2014&utm_medium=email&utm_term=0_57c4746133-d1a9bafbc9-138555905

DISTRIBUTION information – June 2014 Lola’s Organic Farm field day:

 http://georgiaorganics.org/2014/06/field-day-lolas-organic-farm/

 http://growinggeorgia.com/news/2014/06/talking-high-tunnels-organic-weed-management-nrcsgeorgia-organics-workshop/

 http://georgiaorganics.org/2014/06/field-day-lolas-organic-farm/??

Our workshop demonstrations, discussions provided important information and networking opportunities for county collaborators, and Georgia Organics, NRCS and SSARE identifying opportunities for assistance to small farmers, minority farmers, beginning farmers and gardeners interested in improving their farm enterprises and wanting to learn more about organic and sustainable agriculture, etc.  This SSARE Producer Grant provided an opportunity for farmers to learn about the role that SSARE plays in our State and Region and the sustainable and organic agricultural practices that could benefit their farm operations.  

November 2014 we were speakers/presenter participants in the Southeast Georgia Growing Local and Sustainable Conference in Reidsville, Georgia (Tattnall County High School). Our topic, “Non-Toxic Farming”/SSARE Producer Grant (Mechanical and biological strategies to remove invasive common Bermuda grass in preparation for organic vegetable production on raised beds) – we provided information about our SSARE Producer Grant Project,  project’s successes, benefits to sustainable ag farmers,  what we have learned,  discussion.?

Collaborators: