Plows and Pitchforks

Plows and Pitchforks
Fall has always been my favorite season of the year. The constancy of lumbering combines and the speed and efficiency of the harvest support team adds to the romanticism surrounding the family farm. There is no better entertainment on fall evenings than watching the neighborhood farm equipment light up the fields as the sun retires for the evening.

The fun part is honing the ability to correctly guess which neighbor is running which piece of machinery solely by matching its movements to the experience level and temperament of its operator.

There is another spectator who is neither entertained nor impressed by this rural spectator sport. This spectator is better known in aggregate as the land, or in the realm of earthen life, its common name is soil.

The soil is where the plants obtain their nutrients, so why isn't the soil happy with its role in feeding life on earth? The answer lies with the weight of ever larger farm equipment and soil compaction.

Dr. Des McGarry's remarks at the 2001World Congress on Conservation Agriculture expanded this thought. "Of all of the forms of land degradation in the world, soil compaction is certainly one of the most readily reversible and also totally unnecessary ? from the subsistence farmer to large, mechanized corporate farms soil compaction is a lose, lose, lose situation."

Dr. McGarry also pointed out that the costs of soil compaction can add up. The most direct cost can be up to 100 percent yield loss in some areas. Other costs include seed and fertilizer inefficiency as well as the costs of both forming and removing soil compaction. Soil compaction occurs every time tractors move across a field during tillage.

Bob Durland, of South Dakota State University wrote an Extension Extra in 2002 titled, "Till for a Reason." He stated that, "before pulling a tillage implement into a field, evaluate the situation. If there aren't any weeds to kill, if there is not a compaction layer to breakup and if not preparing the seedbed, then it is better to leave the tillage implement in the shed." He alluded to the fact that expense is accrued every time you take your tractor across the field. A side effect of equipment operation is the formation of compacted soil.

However, this year's drought can be an indicator of soil compaction problems in your field. In 1988, Jim Gerwing wrote Extension Extra 8041 that dealt with the problem of soil compaction in dry years. He pointed to the fact that compacted areas are "low places in fields which normally stay wet longer." Interestingly, the soil compaction problem is not usually caused by a dry year, but during previous wetter years.

The low areas of the field typically stay wet longer than the rest of the field, causing them to suffer from greater compaction. Compacted soil in the wetter areas of the field don't harm the crops as much during wet years because the plant roots don't need to grow very far to reach water. Jim Gerwing explained that, "In dry years ? the crops in these areas suffer severe drought stress due to limited root systems. In some cases, there is adequate moisture within one foot of the surface but roots can't reach it because of a compacted layer directly below the tillage zone."

To determine if soil compaction is a problem on your farm, researchers suggest to dig up some plants and observe their root structure, and to also look for evidence of roots growing past the tillage zone.

If compaction is found to be a problem, then Jim Gerwing suggested that, "Tillage should penetrate below the compacted zone ? tillage to destroy deep compaction must be done when soils are dry."

Given our lack of moisture this growing season, it may be a good idea to evaluate potential problem areas during harvest and perform deep tillage this fall in those areas where soil compaction is identified.

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