Soybean South


Residue Beans

Conservation tillage provides many benefits but also requires above-average
management on the producer’s part – particularly when planting soybeans.

By John Woodruff
Emeritus Faculty
UGA Extension

Conservation tillage offers distinct advantages but above-average management is required to attain good crop stands and weed control. Management practices for conservation tillage vary depending upon the crop, soil type and weed pressure. Listed below are some basic principles from the 2009 Georgia Soybean Production Guide that apply to all conservation-tillage systems.

Seeding rates and row spacings
Good soybean stands are more difficult to obtain with conservation tillage than with clean tillage. To help reduce this problem, soybean conservation-tillage seeding rates should be increased 10 to 15 percent. Conservation tillage seeding depths should be about the same as clean tillage.

Some conservation tillage planters tend to make a furrow when planting. These should be adjusted so that the furrow depth is as shallow as possible. Deep furrows should be avoided since high-intensity rains can wash excessive amounts of soil over the seed or concentrate herbicides near the seed and cause injury or stand reduction.

Soybeans do not normally accumulate quite as much vegetative growth with conservation tillage as with clean tillage. Therefore, in late-plant situations, close rows could be especially important for conservation tillage.

Row spacings of 36 inches are common for soybeans, but the crop could benefit from more narrow spacings of 20 to 30 inches. Narrow rows help ensure full canopy development that can help reduce soil moisture loss and suppress late-emerging weeds.

Conservation-till drill planting
Drill planting can be successfully used with conservation tillage, but soil compaction can be a problem, and getting acceptable crop stands is not easy. The soil compaction problem may be corrected by deep chiseling in the fall ahead of plant-ing wheat or a cover crop.

Winter grazing can re-establish soil hardpans on Coastal Plain soils. Because of this situation, drill planting is generally not a good way to plant behind winter grazing.

Stand problems with conservation-tillage drill planting are usually associated with getting litter in the seed furrow and poor seed-to-soil contact. The litter problem can sometimes be reduced by using a smooth coulter instead of the normal fluted coulters on drill planters.

Get better stands with row planters
To get uniform seeding depth, conservation- tillage drills should be equipped with double-disk furrow openers and disks that have bands for depth control. Good seed-to-soil contact is essential so special narrow press wheels will usually be needed. Extra weights on the planter are often needed to get adequate soil penetration and seed coverage.

Soil moisture and temperatures should be watched carefully, also.

Better stands can be obtained with conservation tillage row planters than with conservation tillage drill planters. This is apparently true because row planters place seed in moist soil and give better seed-to-soil contact.

No-Till Recommendations

1. Rotate grass and legume crops to reduce the presence of disease and nematode problems.

2. Plant winter cover crops for erosion control and moisture conservation. Use a herbicide to kill the cover crop when planting soybeans.

3. To ensure adequate soybean stands with conservation tillage, adjust planters to pull straw and crop litter away from seed furrow, increase the seeding rate 10 to 20 percent and use a narrow planter packer wheel (two inches wide or less) to break up soil clods and ensure good seed-to-soil contact.

4. Decrease row width for conservation tillage, especially if planting is under less than optimum conditions.

5. If drill planting, use units with cutting coulter, double-disk openers, depth bands or some means of positive depth control/narrow packer wheels.

6. Manage wheat stubble so that it does not interfere with soybean stands and herbicide performance. Cut it as high as practical to reduce dragging. Use a lateral bar on herbicide sprayers to press it down and away from herbicide spray.