Midwest Vegetable Guide - 2022 - 17

Soil Fertility and Nutrient Management
Broccoli, cauliflower, celery, beet, turnip, and rutabaga are
likely to respond to B applications of 3 to 4 pounds per acre
when soil levels are low. Cabbage, carrot, lettuce, parsnip,
radish, spinach, and tomato show a medium response and
usually benefit from 1 to 2 pounds of B per acre.
Bean, peas, and cucumber are sensitive to B, so do not apply
it to these crops.
You can add B to the soil with Borax (which contains 10.6
percent B) or Solubor (which contains 20.5 percent B). B
applications are most effective if applied with the fertilizer at
preplant or at the time of transplanting.
Mid- or late season foliar applications are not as effective as
early granular or foliar applications. It is important not to
exceed recommended B rates to avoid toxicity in subsequent
B-sensitive crops. Carryover is most likely after a dry fall and
winter.
Other micronutrient deficiencies are rare in field-grown
vegetable crops in this region.
Fertilizer and the Environment
Nitrogen from both natural (manure, compost, green manure)
and synthetic sources can be lost from fields, which can
pollute water and increase greenhouse gasses that contribute
to climate change. Similarly, natural and synthetic sources of
P can move out of cropped areas and pollute waterways. With
proper fertilizer management, vegetable producers can
minimize environmental impacts and improve fertilizer use
efficiency. Growers should know their crops, account for the
nutrient values of all soil amendments, and test soils and
plants to support their fertilizer decisions.
Split N applications - applying some N before planting and
sidedressing the rest during the season - are generally more
efficient than complete preplant applications. However, split
applications require growers to pay attention to crop growth
and sidedress at the appropriate times: before crops are
stressed, and early enough to allow crops to mature.
Banding P at planting (with or without some P being
broadcast/incorporated) is generally more efficient than
broadcasting all P. Sidedressing P is not recommended
because it is not mobile in soils.
Generally, K and the minor elements do not contribute
significantly to groundwater pollution, but growers should
manage them properly to minimize costs and maximize
efficiency.
Minimizing soil erosion, timing irrigation properly, and
avoiding excess irrigation will also improve fertilizer use
efficiency and reduce losses from the field.
Animal Manures and Composts
as Fertilizers
Animal manures and composts can provide significant
nutrients to plants. The nutrient content of manures varies
among animal species and within each species. Nutrients in
composts can vary even more and depend on parent material
and processing. Test manures and composts to determine the
potential nutrient contributions and plan application rates
based on their nutrient content. Avoid using composts of
unknown origin or parent material. Improperly made
composts, be they of rural or urban origin, can contain heavy
metals, inorganic debris, diseases, and insects that are
unwelcome on your fields.
It is important to consider the timing of manure and compost
applications. Fresh manure has potential to " burn " a crop
because it often contains high levels of ammonia, and fresh or
casually " aged " manure often contains human pathogens. For
these reasons, it is rarely acceptable to apply fresh or " aged "
manure to food crops while they are growing. Generally, a
fall application is acceptable, ideally to a cover crop, and at
least nine months before harvesting the next vegetable crop.
Any use of manure or composts should follow current Good
Agricultural Practices (GAPs), and mandates of the Food
Safety Modernization Act (FSMA). The demands of a
particular market may be more stringent. For guidance about
GAPS and FSMA, see Produce Food Safety section.
Fertilizer Application Methods
Fertilizer application timing and methods vary from farm-tofarm
depending on cultural practices and equipment. This
section outlines common practices of efficient fertilizer
placement and utilization. These practices can be modified to
suit particular situations.
Usually, growers can apply at preplant and disk into the soil
50-60 percent of the recommended N and all of the P and K
fertilizer. This is especially true when the rates of a complete
fertilizer will require more than 400 pounds per acre.
We recommend band application for many direct-seeded
vegetable crops. This technique applies a concentrated line of
fertilizer 2 inches to the side and 2 inches below the seed
furrow. This is an efficient way to apply fertilizer, and much
of the P and K fertilizer can be applied this way. However, do
not make banded fertilizer applications exceeding 80 pounds
per acre of N plus K - this can injure seed.
For crops grown on plastic mulch (with or without a raised
bed) growers may apply fertilizer just to the bed area. As with
broadcast applications, growers can apply a portion of the
recommended N, and all of the P and K before planting. If N
will be supplied through fertigation during the season, apply
Midwest Veg Guide 2022
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Midwest Vegetable Guide - 2022

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