Great improvements in soybean varieties, the Roundup Ready (glyphosate) technology, other herbicides for weed control, moisture conservation and erosion concerns all have helped speed the adoption of reduced and zero-till practices for soybean production in the Northern Great Plains. Expansion of soybean acres have occurred both west and north in North Dakota and west in Manitoba in the past several years.

The American Soybean Association recently completed a study survey on no-till soybean management and production practices. This survey study was conducted in the major soybean growing regions of the U.S.

The key objectives of the study included:

To identify the tillage practices soybean growers utilized in 1996 and compare those to

present day tillage practices.

To identify the changes in technology that have made it possible for growers to reduce

tillage in soybeans.

To identify obstacles that are currently preventing growers from trying to reduce tillage

practices in soybeans.

No-Till soybean acres have more than doubled to 49% of the total soybean acres and

reduced till acres have increased over one-fourth, to account for 33% of the soybean acres.

The percent of soybean acres drilled or planted in narrow rows of 20 inches or less have

increased by one-fourth to account for 75% of the total soybean acres.

Roundup Ready soybean acres have increased over 50 fold to account for 74% of the total

soybean acres growing in 2001.

In this same approximate time frame, growers stated they have undertaken the following cultural practices in soybeans:

53% of the growers are making fewer tillage passes in soybeans

73% of the growers are leaving more crop residue on the soil surface

48% of the growers have increased their no-till soybean acres.

Key Results:

Roundup Ready technology has been a key factor enabling growers to undertake this tillage reduction revolution in soybeans. When asked, "In the past 5 years, what changes in technology such as equipment, chemicals or seed have made it possible for you to reduce tillage or increase crop residue in soybeans?" Growers stated on an unaided basis:

47% - Equipment, including improved tillage equipment and better planters and drills

12% - Better chemicals not specified

When asked which of six factors had the greatest impact toward the adoption of reduced tillage or no-till in soybeans during the past 5 years, growers indicated:

The introduction of Roundup Ready soybeans 54%

Improvements in reduced or no-till drills and planters 15%

Availability of over the top or in crop herbicides 12%

Availability of reduced or no-till drills and planters 9%

The cost of burn down herbicides 6%

The availability of burn down herbicides 3%

Approximately 10 percent of the soybean growers surveyed indicated they have not considered trying reduced till or no-till soybeans. Equipment issues are a frequently mentioned obstacle in trying reduced or no-till soybeans. The major obstacles that have prevented them is stated on an unaided basis include:

The price of equipment 26% Higher weed control costs 9%

Slow growth/lower yields 20% Ground is too cold in Spring 9%

Ground is too wet in Spring 16% Poor soil/seed contact 6%

Don’t have proper equipment 15% Concerns about soil compaction 4%

Doesn’t fit rotation or system 11% Roundup Ready seed is not available 2%

Other Findings:

There are important and significant differences in farmers currently planting Roundup Ready soybeans compared to farmers not planting Roundup Ready soybeans. Specifically, farmers currently planting Roundup Ready soybeans:

• Have a significantly higher proportion of their total soybean acres in no-till or reduced till and in

• They state they are making fewer tillage passes than they did five years ago.
• They state they are leaving more crop residue on the soil surface than they did five years ago.

There are several differences in Roundup Ready soybean farmers and non-Roundup Ready soybean farmers perceptions toward the advantages of no-till and reduced till and role of seed technology plays relative to no-till or reduced till. Both groups share the same perceptions that reduced till soybeans save fuel and labor. Roundup Ready users are more likely to hold the following perception as compared to non-users:

No-till soybeans save labor

Roundup Ready soybeans have made it possible for more growers to adopt no-till or

reduced till practices in soybeans.

Seed technology has made no-till and reduced till soybeans feasible in their operations.

Lower herbicide costs have helped farmers adopt no-till and reduced till soybeans.

The effect of row spacing on soybean yield has been a frequent question of no-till soybean growers. Research results show that maximum yields are obtained with earlier canopy closure, thus competing better with weeds resulting in higher yields. In North Dakota, drilled soybeans in narrow rows have resulted in yield increases ranging from 12 to 20 percent over wide rowed soybeans (30 inches).

Seeding rates:

In most situations, harvest stands are always significantly lower than seeding populations. The percentage of plants that survive to harvest is generally lower with no-till than with conventional tillage. Cold soils, seed placement and other factors are involved. The final population is a function of seeding rate and growing conditions throughout the season. Growers can’t control the growing conditions but can control the quality and quantity of seeds being planted. When determining rate, always take into account the number of seeds per pound. Soybeans can range from 2000 to 4500 seeds/lb. Seeding rates of solid seeding soybeans are in the 200,000 to 210,000 seeds/A range. (See Table 1.) This is a good rate to use with both conventional and Roundup Ready soybeans. However, if one wishes to cut input costs, a rate of 165-175,000 beans/A would be adequate for Roundup Ready soybeans if weeds can be kept under control. In wide rows (30 inches) then 150,000 seeds/A is adequate. Also adjust seeding rates for live seed dropped based on germination tests. Also never use "old" soybean seed as seedling vigor and germination percentages are usually unsatisfactory.

Inoculation of soybeans:

Soybeans are legumes and form a symbiotic relationship with soil rhizobia to fix nitrogen. Inoculating seed is a must in areas when little history exists of producing soybeans. In the Northern Great Plains it is usually very beneficial to inoculate with the proper strains of rhizobia. Soil nitrogen levels of greater than 80 pounds/A will result in poor nodule formation and poor inoculation of soybean roots. Under extreme dry conditions the nodules can slough-off and not be effective. Generally a N credit of 40 lbs/A are given to soybeans in a crop rotation sequence to crops which follow. Cereals or corn respond very well to soybeans in a rotation.

Yields of soybeans in zero-till have been greater than conventional soybeans at sites in Minot, Washburn and Hettinger, N.D. See Tables 2 and 3. This yield increase can be attributed to extra available water under the zero-till systems. The extra two inches of water available under zero-till soybeans is critical at flowering, pod set and pod filling time. Available water, N via fixation and season growing temperature are all critical to successful soybean production in northern and western expansion regions.