With these advanced global positioning systems, a
single reference station on the farm provides the real-
time corrections to less than 1 inch level of accuracy,
which facilitates precision steering of field equipment.
Controlled traffic lanes can therefore be laid out with
unprecedented accuracy, and water (for example, drip
irrigation) and nutrients can be applied at precise dis-
tances from the crop (figure 15.11).
A permanent (raised) bed system is a variation on
controlling traffic in which soil shaping is addition-
ally applied to improve the physical conditions in the
beds (figure 15.11, right). Beds do not receive traffic
after they’ve been formed. This bed system is especially
Figure 15.10. A tractor with wide wheel spacing to fit a controlled traffic attractive where traffic on wet soil is difficult to avoid
system.
(for example, with certain fresh-market vegetable crops)
crop rows and traffic lanes remain recognizable year
and where it is useful to install equipment, such as irri-
after year. Ridge tillage, in fact, dictates controlled traf-
gation lines, for multiple years.
fic, as wheels should not cross the ridges. Zone- and
no-till do not necessarily require controlled traffic, but
SUMMARY
they greatly benefit from it, because the soil is not regu-
Compaction frequently goes unrecognized by farmers,
larly loosened by aggressive tillage.
but it can result in decreased yields. There are a number
Adoption of controlled traffic has been rapidly
of ways to avoid the development of compacted soil,
expanded in recent years with the availability of RTK
the most important of which is keeping equipment off
(real-time kinematic) satellite navigation systems.
wet soil (when it’s in a plastic state). Draining wet soils,
Figure 15.11. Controlled traffic farming with precision satellite navigation. Left: Twelve-row corn-soybean strips with traffic lanes between the fourth and fifth row from the strip edge (Iowa; note that both current- and previous-year harvested crop rows are still visible). Right: Zucchini on mulched raised beds with drip irrigation (Queensland, Australia).
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Building SoilS for Better CropS: SuStainaBle Soil ManageMent