Optimizing sorghum-sudan/forage soybean cover crop populations and screening sorghum varieties for organic cover crop performance, forage, and seed production in the Northern Great Plains region

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2010: $17,912.00
Projected End Date: 12/31/2012
Region: North Central
State: North Dakota
Project Coordinator:

Annual Reports


  • Agronomic: soybeans
  • Animals: bovine


  • Animal Production: feed/forage, grazing management, pasture fertility, grazing - rotational
  • Crop Production: cover crops, multiple cropping, nutrient cycling, tissue analysis
  • Education and Training: demonstration, farmer to farmer, on-farm/ranch research
  • Farm Business Management: budgets/cost and returns, feasibility study, agricultural finance
  • Natural Resources/Environment: biodiversity, soil stabilization
  • Pest Management: allelopathy, competition, economic threshold, physical control, smother crops, weed ecology
  • Production Systems: agroecosystems, holistic management, organic agriculture, integrated crop and livestock systems
  • Soil Management: soil analysis, nutrient mineralization, soil microbiology, soil chemistry, organic matter, soil physics, soil quality/health
  • Sustainable Communities: local and regional food systems, sustainability measures

    Proposal summary:

    Sorghum [Sorghum bicolor spp. bicolor], sorghum-sudangrass [Sorghum bicolor X S. bicolor var. sudanense] produce multiple documented benefits including abundant biomass, dense sub-soiling root systems (to prevent soil erosion, sequester carbon, increase soil organic matter, and improve soil quality) that scavenge and store available soil nutrients such as nitrogen (N) and potassium (to reduce nutrient leaching), and nematode and weed suppression (a process called alleopathy) (Clark, 2007). A mixture of forage soybeans and sorghum can capitalize on more above-ground and below-ground resources than monocultures, including nutrients, water, and light. Sorghum is a heavy N feeder with a tall, upright growth habit and a weed suppression effect, while the soybean fixes N and forms a dense canopy under the sorghum. In addition, sorghum-sudangrass can be utilized as a cover crop, forage, and/or for grazing and regrowth when other forages are in short supply. These complimentary benefits are documented, however, it recognized that optimizing cover crop mixes for a particular climate, soil, and farming system requires trial and error (Treadwell et al., 2010). Farmers in the northern latitudes can purchase sorghum hybrids and sorghum-sudan hybrids; most were bred for the south, which is the primary sorghum production region. There are no commercially available, open-pollinated sorghum varieties for forage and cover crop systems in the northern latitudes, therefore, seed-saving is not an option. [The seed of hybrids generally are not true-to-type, meaning the offspring will not exhibit the same characteristics of its parents; most commercially available hybrids are licensed under Plant Variety Protection (PVP). The owner of the PVP variety has the exclusive right to control the production and marketing of their variety. Seed of these varieties can only be sold with authorization from the owner.] The National Organic Program requires the use of certified organic seed when available and requires the use of cover crops in organic production systems. Certified organic cover crop seed is in short supply. This represents an opportunity for the development of regional seed systems. The goal of this two-year project is to increase the utilization of sorghum in organic cover crop mixes, forage systems, and seed production systems in the Northern Great Plains region. Objective 1: Identify best management practices for implementing forage soybean/sorghum-sudan mixtures in organic farming systems for maximum biomass production, weed control, nitrogen fixation, and nutrient density of forages in the Northern Great Plains region. Objective 2: Screen 40 sorghum accessions (20 per year) for adaptability and suitability to organic forage and cover crop systems, and regional seed systems in the Northern Great Plains. Methodology A forage soybean and sorghum-sudan variety will be combined at two different mixing ratios. Planting will take place about mid-June when soil temperatures reach about 65-70 degrees F. to ensure faster germination, emergence, and vigorous growth. These two mixing ratios will be planted using two different seeding rates, resulting in four treatments of varying population ratios and planting densities. Each treatment will be planted to one drill pass in strips the length of the field (up to 1/2 mile long) to distribute across a range of soil conditions in the field. The treatments will be replicated at the Berry and Gross farms (4 treatments x 2 replications) for 8 strips. Dr. Dwayne Beck, Dakota Lakes Research in Pierre, SD and Ken Miller, Burleigh County Conservationist in Bismarck, ND have experience utilizing cover crop mixes in no-till systems. We will draw upon their experience to inform our mixing rates, planting densities, and dates. Farmer participants will detail their field history including previous crops, green manures, manure applications, and tillage operations. A soil test will be conducted in the spring and fall of Year 1 and 2 on all the fields to monitor changes in soil quality. Each farmer will carry an observational log for recording planting dates, mixing ratios, and seeding rates, with data sheets for recording their six observations, providing data on seedling vigor, rate of growth/plant height, and days to canopy closure. Each farmer will collect biomass and forage samples both years. David Podoll and Devan Hafner will conduct sorghum variety trials on open-pollinated sorghum accessions obtained from the USDA Germplasm Resources Information Network (GRIN), cooperating plant breeders and seed companies. At least 2 commercially available hybrids will be included as “check” varieties for comparison. Year 1: 20 sorghum accessions and 2 commercial hybrid “check” varieties will be planted, each in a 5-foot row, and screened for the following traits of interest: rate of emergence, seedling vigor, rate of growth, canopy, stand-ability/stalk strength, days to flowering, presence or absence of a brown midrib (BMR, an indicator of grazing palatability), size of the panicle (seed head), cold tolerance at emergence and all phases of plant growth, and ability to produce viable seed this far north. Year 2: 20 more accessions and 2 commercial hybrid “checks” planted in 5-foot rows, as in Year 1, and screened for the traits of interest listed above. In addition up to 6 promising accessions from Year 1 will be planted in a 2.5 ft. x 2.5 ft. block and again evaluated for all the above traits of interest, as well as the rate of canopy closure and biomass production. Project Cooperators Lealand Schoon, District Conservationist, White River NRCS, will provide assistance with biomass and forage sampling and hosting a field day at the Ray Berry farm. Steve Zwinger, a research agronomist at the North Dakota State University (NDSU) Carrington Research Extension Center (CREC) will provide technical assistance with biomass and forage sampling, indentifying sorghum accessions to be screened, and overseeing the second sorghum variety trial. Devan Hafner, a Northern Plains Sustainable Agriculture Society (NPSAS) intern, will manage the second sorghum variety trial under Zwinger’s direction. Plant breeders, Matt Kolding (Oregon State University; retired) and Frank Kutka (Seed We Need Project; NDSU) will work with us to identify sorghum accessions possessing drought and cold tolerance traits for trialing in the Northern Great Plains region. Kolding worked to breed cold tolerant sorghum varieties for the Pacific Northwest. Kutka will provide preliminary screening data of early maturing, cold tolerant, open-pollinated (OP) forage sorghum accessions and will assist in researching GRIN for accessions with the potential to mature in our short growing season. NPSAS staff will provide assistance with press releases, outreach, and field day and conference organizing. The Foundation for Agricultural and Rural Resources Management and Sustainability(FARRMs) staff will also provide assistance with publicity and outreach.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.