Agriculture Reference
In-Depth Information
by a buyer, growers should assess the potential
market outlets thoroughly prior to planting a
variety that is unfamiliar to buyers. On the other
hand, if a new variety gets ample exposure and
is promoted prior to hitting the market, early
adopters may find new varieties a financial
boon, especially when supplies of the new
variety are limited. Similarly, marketers and
growers can use exclusive-rights ownership to
control the supply of privately owned varieties,
with the hope of reaping financial rewards
greater than those coming from public varieties
(Guenthner, 2003).
Ideal potato fields have limited slope, well-
drained, fertile, and non-compacted soil with
limited disease and pest pressure, overhead irri-
gation and/or sufficient rainfall, and are free
from damaging or quarantined pests, rocks,
clods, and excessive debris from previous crops.
Other ideal soil properties include low concen-
trations of salt and sodium and a soil pH of 6.0-
7.5 (Magdoff and van Es, 2000). Medium- to
coarse-textured soils are often favored over
fine-textured soils because they drain more
effectively, thereby preventing anaerobic condi-
tions and uneven soil moisture issues. In
addition, coarser soils are desirable because they
wash easily from tubers, especially when com-
pared to soils with high clay content. Examples
of medium and coarse soils include silt loams,
loams, sandy loams, and sand (McDole
et al
.,
1974).
Weeks, or months, prior to planting, fields
with high levels of disease (verticillium wilt),
weed seeds, wireworm, and nematodes are typ-
ically fumigated with a pesticide. Unless the
grower knows the field history well, soil samples
should be collected and tested to determine dis-
ease and pest load. Soil samples are also recom-
mended for determining soil properties like pH,
nutrient levels, and organic matter.
Prior to planting, and after soil samples
have been analyzed, decisions regarding nutri-
ent source and delivery to the plant must be
made. Overhead irrigation systems allow the
grower to apply fertilizer, water, and plant pro-
tection products (also referred to as fertigation
or chemigation) simultaneously. This offers flexi-
bility throughout the season to match nutrient
applications with plant needs. Where overhead
irrigation is not available, however, growers
must apply fertilizer prior to planting, during
planting, and/or during post-planting tillage
operations. Moreover, once foliage approaches
100% ground cover, tillage operations typically
cease for the growing season. Because early
spring soils are often saturated with water, oper-
ations with overhead irrigation systems may
choose to apply and incorporate some or all fer-
tilizer with ground applicators and tillage equip-
ment prior to 100% ground cover. This ensures
that the plants receive an adequate supply of nu-
trients if early irrigation and fertigation are not
possible. Once fertilizer application timing and
amount is determined, the fields can be tilled
6.2
Pre-Plant Preparation
Many decisions must be made prior to and dur-
ing the planting process. Pre-planting consider-
ations include field selection and preparation,
whole-farm crop rotation, soil testing for nutri-
ents and pests, pre-plant fertilizer and pesticide
applications, time of planting, equipment and
irrigation needs and capabilities, potato variety
and market, postharvest storage, crop and per-
sonnel management, and financial consider-
ations.
Field and soil considerations
Established commercial farms typically engage in a
whole-farm crop rotation strategy where certain
crops proceed or follow others in the same field
across production years. The exception is when
growers choose to lease fields randomly rather
than farm within a set series of fields. Crop rota-
tions vary by region and farms, but the underlying
theme is to prevent build-up of insect pests, weeds,
and diseases, and to maintain or improve the soil
health by cycling particular crops in and out of a
particular field (Magdoff and van Es, 2000). When
growing conditions allow, green manure crops are
often planted in between rotation crops to help
build the soil organic matter, capture and hold
leachable nutrients, prevent soil erosion, reduce
weeds (by allowing germination but not seed
development), and suppress nematode and disease
activity with natural plant compounds like glucosi-
nolates found in most
Brassica
species (McGuire,
2003).
