United States Department of Agriculture

A Systems Approach 

for U.S. Soybeans

Recommended best practices for 

reducing weed seeds in U.S. soybeans
United States Department of Agriculture

Farm-to-export systems approach

A suite of recommended best practices that can help reduce weed seeds 

in soybeans on farm, at U.S. grain elevators, and the point of export.

The systems approach is voluntary. Producers, handlers, and exporters are encouraged to consider and use those 

best practices that are appropriate for their geographic area and their farm or business operation.
United States Department of Agriculture

General Weed Management

Develop a tailored weed management plan

 Regularly scout production areas to see which weed 

species are present. 

 Consider weed biology when selecting weed management 

controls.

 Include a mix of chemical, cultural, and mechanical 

controls. 

 Regularly vary weed management practices to eliminate 

weeds, avoid development of herbicide resistance, and 

discourage the buildup of any one weed type.

 Work with Extension agents or crop advisers to design 

short- and long-term plans tailored to your crop rotation, 

your region, and the weed species present in your fields.
United States Department of Agriculture

General Weed Management

Rotate crops and double-crop

 Use two or more crops in a rotation to lower weed 

densities, increase crop yields, and improve soil quality.

 Select rotational crops that will be sprayed with herbicides 

with different modes of action to minimize the evolution and 

spread of herbicide-resistant weeds.

 Consider double-cropping. The residue from the first crop 

helps to suppress weeds, reduce erosion, and limit pest 

populations while the second crop is growing. This 

approach can increase field yield and reduce overall 

herbicide applications. 
United States Department of Agriculture

General Weed Management

Use cover crops

 Cover crops can increase soybean yield and suppress 

weeds.

 Select a cover crop that is suitable for your region.

 Remove the cover crop right before planting soybeans 

(as early as 1 month or as late as 5 days before planting).

 Consider using a cover crop between soybean rows.
United States Department of Agriculture

General Weed Management

Diversify herbicide use

 Use a variety of herbicides with different modes of action. 

 Use a combination of pre- and post-emergence herbicides 

with residual effects that will last the entire crop season.

 Seek advice from Extension agents and crop advisers on 

diversifying your herbicide use, identifying the appropriate 

tank mixes, and tailoring the modes of action to your 

specific needs.
United States Department of Agriculture

General Weed Management

Manage weeds in field borders

 Control weeds in field borders, including in ditches, along 

access roads, and in sloughs. 

 Frequently mow the perimeter to prevent weed 

reproduction and create a barrier between the field and 

outlying areas.
United States Department of Agriculture

General Weed Management

Control late-season weeds

 Consider using a pre-harvest herbicide or manual weed 

removal to control late-season weeds.

 Incorporate some tillage, if possible, when other weed 

control measures are ineffective or not feasible.
United States Department of Agriculture

Planting

 Start with clean seed.

 Avoid planting soybeans in fields with a history of 

heavy weed infestations until the weeds are brought 

under control.

 Plant soybeans in narrow rows to allow plants to quickly 

form a closed canopy and out-compete weeds.

 Plant early in the season (late April to early May in the 

north; mid-April to mid-June in the south, depending on 

variety) to help plants compete against weeds and 

increase yields.

 Use soybean seed inoculated with nitrogen-fixing bacteria.

 Adjust irrigation timing and amount to minimize the 

benefit to weeds. 
United States Department of Agriculture

Harvesting

 Avoid harvesting soybeans growing in high-density 

weed patches.

 Adjust combine settings to remove weed seeds. 

 Regularly clean storage bins, augurs and legs, transport 

vehicles, and farm equipment to prevent weed spread 

and avoid contaminating soybean with other grains, 

especially corn.

 Destroy weed seeds that are separated from grain 

or left in the field to keep them from entering the soil 

seed bank. 
United States Department of Agriculture

Handling

 Examine soybeans upon arrival for weed seeds, especially 

ragweed, Johnsongrass, cocklebur, pigweed.

 Consider separating weed seeds from soybeans through 

mechanical cleaning or other means and then destroying 

the seeds.

 Ensure bins, belts, and scales are free of other grains, 

especially corn, which some countries consider a noxious 

weed.
United States Department of Agriculture

Sampling, Inspection, and Analysis

USDA and U.S. trade associations will monitor weed seed and 

foreign material content in soybeans to evaluate the effectiveness 

of the systems approach. This includes:

 Conducting a national survey at country and export 

elevators.

 Analyzing data to identify opportunities for improving the 

results of the systems approach.
United States Department of Agriculture

National Sampling Plan

Data elements: • sample weight • total foreign 

material (FM) 

weight

• total weed seed 

weight 

• soil FM weight • pods and stems, 

soybean pieces, 

and number of 

seeds

• weight of all seeds 

by species
United States Department of Agriculture

Trade Support

USDA is working closely with foreign trading partners to ensure 

uninterrupted trade in U.S. soybeans. 

This includes bilateral cooperation between USDA and foreign 

officials to address any technical issues that might affect the entry 

of soybeans into the importing country.
United States Department of Agriculture

Farm-to-export systems approach

By participating in the systems approach, 

everyone along the supply chain can help maintain 

and enhance the value and safety of U.S. soybeans.