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60 Ways Farmers Can Protect  Surface Water
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13. Reduce Soil Compaction and Increase Filtration

Field with compacted soil When soil compaction becomes excessive, you end up paying in a number of ways—lower crop yield and a greater potential for soil erosion and water runoff.

The surface of a compacted soil is more likely to seal, which means water has a harder time moving down through the soil. Water accumulates on the surface and moves downslope, carrying eroded soil, nutrients, and pesticides.

Compaction Prevention To prevent soil compaction, avoid wheel traffic and tillage of wet soils; use wider tires, dual tires, or tracks; minimize tractor weight; maintain the minimum tire inflation pressure needed for an acceptable tire life; avoid using oversized equipment; try to combine field operations to make fewer passes over the field. . .
Compaction Prevention . . . keep soil-engaging components of your equipment sharp; add organic matter to the soil; vary the depth of primary tillage from year to year to prevent formation of a "plowpan"; and space the wheels on production and harvesting equipment equally so they follow the same paths. Also, use tractors with four-wheel or mechanical front-wheel drive because the front and rear wheels follow the same path.
Subsoiler in a field In an excessively compacted field, you can use the subsoiler or paraplow to sufficiently loosen the soil. However, studies have shown that except for possibly improving drainage, it is not necessary to loosen the soil to the depth that some of these implements—especially the subsoiler—are designed to operate.
close up of subsoiling Keep in mind that the effect of subsoiling may be temporary. For the first few rainfalls after subsoiling, the infiltration of water into the soil will be high. But eventually the rain will cause the surface to seal, and runoff may be the same as if you hadn't subsoiled. If subsoiling is necessary, do it on the contour and when the soil is dry.
Farmer using a soil cone penetrometer To measure compaction, a soil cone penetrometer can give a more objective indication than other systems. A cone penetrometer, available for about $150, measures the amount of resistance encountered when probing the soil, but its readings are affected by soil moisture and require careful interpretation. Also, with a penetrometer it is difficult to tell if a dry soil is compacted.

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