For Fertilization: lawns | gardens |
WATER QUALITY AND USE:
MANAGEMENT PRACTICES FOR FERTILIZATION [continued]
Ch. 16, pp. 7 - 9
As in the case of lawns, home vegetable and ornamental
gardens can benefit from the use of fertilizers. Several
management practices should be considered before using any
fertilizers on the home garden to maximize the benefits to the
plants while minimizing the possibility of groundwater
Soil Testing - Soil testing can be helpful if
your garden is not performing as it should. Soil testing is costly
for a home owner since home test kits are of little value for
Arizona soil. To obtain an accurate soil test a soil sample must
be sent to a certified soils laboratory. County Extension offices
have a list of labs for your use. In general, soils in Arizona
will be lacking in nitrogen and phosphate. Regular applications of
these two elements should prevent the majority of problems due to
nutrient deficiencies. To avoid over application of nitrogen it is
best to apply small amounts of more frequently.
Tilling the Soil _ This can be beneficial if
done at the proper time. Tilling aerates the soil and can help
control weeds. Organic matter may also be incorporated when
tilling. If done when the soil is too wet or too dry however,
tilling can destroy soil structure, which may take years to
rebuild. Tilling wet soil can also lead to the formation of a
hardpan, inhibiting root growth. Both of these may contribute to
soil erosion and loss of nutrients into groundwater supplies. A
no-till approach or a system of raised beds can reduce nutrient
and soil loss even more. Tilling in nutrients nitrogen and
phosphate will help in the availability of these elements.
Organic Amendments - Compost, manures, and
mulches can be very beneficial to the soil by improving its
structure, adding nutrients, and increasing its water and nutrient
holding capacity, and can lessen the chance of groundwater
contamination. Albeit, on short lived or unstable soils organic
matter won't accumulate.
Cover Crops - Cover crops, such as annual rye
or wheat, planted in the garden in the fall, and tilled under in
the spring, can also add organic matter and lessen the chance of
groundwater contamination. A leguminous cover crop such as alfalfa
or clover can also add nitrogen to the soil when tilled in. Cover
crops, compost, and manures also add trace elements, which are
essential for good growth, though only needed in small amounts.
Fertilizers - Fertilizers for the garden may be
either organic or synthetic. Both organic and synthetic
fertilizers can be fast or slow acting. Organic fertilizers can
benefit long term soil conditions by increasing organic matter
content. Garden fertilizers are generally described, by law, with
three numbers such as 10-10-10, or 5-10-5. This is the same as
with lawn fertilizers, although the first number (nitrogen) is
normally lower in garden fertilizers.
Nitrogen is responsible in the plant for producing leaf
growth and greener leaves. A deficiency causes yellow leaves and
stunted growth. The second number, phosphorous, is important in
seed and root development and fruit growth. Potassium, the third
major element, promotes early growth, improves stem strength, and
contributes to cold hardiness.
In the vegetable garden, fertilizer may be incorporated
into the soil either by broadcasting it over the entire garden, or
by applying it in narrow bands on either side of the plants in the
row. Banding it is more efficient, because it uses less fertilizer
and makes it available to the plant closer to the root zone.
Amount, Frequency, and Timing of Fertilizer
Application - Vegetables vary in their nutrient requirements.
Heavy feeders, such as broccoli, sweet corn, and tomatoes may need
more frequent applications of larger amounts of fertilizers than
medium feeders, such as beans, carrots, and cucumbers. A first
application is generally made when the seed is planted, or the
transplant set out.
Depending on the crop, a second application can be made
when the plant flowers, or starts to set fruit. Some crops, such
as corn, benefit from a third application when the silks form. By
sidedressing, the fertilizer becomes available to the plant when
it needs it most. It is important to remember that fertilizer not
utilized by the plant has the potential to leach through the soil
and contaminate the groundwater, or be washed into the water
supply by erosion.