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Fertilizing Your Vegetable Garden - Part 3

Banding:

Banding is one way to satisfy the needs of many plants (especially tomatoes) for phosphorus as the first roots develop. When fertilizers are broadcast and worked into soil, much of the phosphorus is locked up by the soil and is not immediately available to the plant. By concentrating the phosphorus in the band, the plant is given what it needs even though much of the phosphorus stays locked up.

Fertilizing vegetable seeds using the banding method

Figure 1 - Fertilizing vegetable seeds using the banding method

Narrow bands of fertilizer are applied in furrows 2 to 3 inches from the garden seeds and 1 to 2 inches deeper than the seeds or plants. Careless placement of the fertilizer band too close to the seeds will burn the roots of the seedlings. The best technique is to stretch a string where the seed row is to be planted, as shown in Figure 1.

With a corner of a hoe, dig a furrow 3 inches deep, 3 inches to one side, and parallel with the string. Spread 1/2 the suggested rate of the fertilizer in the furrow and cover it with soil. Repeat the banding operation on the other side of the string, then sow seeds underneath the string.

For widely spaced plants, such as tomatoes, fertilizers can be placed in bands 6 inches long for each plant or in a circle around the plant. Place the bands 4 inches from the plant base. If used in the hole itself, place the fertilizer at the bottom of the hole, work it into the soil, and place a layer of soil about 2 inches deep over the fertilized soil before putting the plant in the hole.

Recommended application rate:

Apply one pound of 10-10-10 or two pounds of 5-10-5 (or 5-10-10) per 100 feet of row.

Starter solutions:

Another way to satisfy the need for phosphorus when setting out transplants is through the use of a liquid fertilizer high in phosphorus as a starter solution. Follow directions on the label.

Side-Dressing:

Dry fertilizer is applied as a side dressing after plants are up and growing. Scatter fertilizer on both sides of the row 6 to 8 inches from the plants. Rake it into the soil and water thoroughly.

Recommended application rate:

Apply one pound of 10-10-10 or two pounds of 5-10-5 (or 5-10-10) per 100 feet of row.

Foliar Feeding:

Foliar feeding is used when insufficient fertilizer was used before planting, when a quick growth response is wanted, when micronutrients (such as iron or zinc) are locked into the soil, or when the soil is too cold for the plants to use the fertilizer applied to the soil. Foliar-applied nutrients are absorbed and used by the plant quite rapidly. Absorption begins within minutes after application and, with most nutrients, it is completed within 1 to 2 days. Foliar nutrition can be a supplement to soil nutrition at a critical time for the plant, but not a substitute since greater amounts of plant material are needed than what can be absorbed through the plant leaf at any given time. At transplanting time, an application of phosphorus spray will help in the establishment of the young plant in cold soils. For perennial plants, early spring growth is usually limited by cold soil, even when the air is warm. Under such conditions, soil microorganisms are not active enough to convert nutrients into forms available for roots to absorb; yet, if the nutrients were available, the plants could utilize them. A nutrient spray to the foliage will provide the needed nutrients immediately, allowing the plants to begin growth.

Liquid feeding is appropriate for container plants to supply needed nutrients throughout the growing season. The commercial forms are generally cost-prohibitive for continued use in the garden where a greater soil volume is available to the plant roots. Instead, liquid feeding is more a one-time procedure, either as a transplant starter or as a foliar feeding to correct a deficiency in a major or trace element.

If a foliar feeding is desired, follow directions carefully. Using too much fertilizer, especially the synthetic forms, can quickly burn the foliage.

Timing of Fertilizer Application:

Soil type dictates the frequency of fertilizer application. Sandy soils require more frequent applications of nitrogen and other nutrients than do clay-type soils. Other factors affecting frequency of application include the type of crop, the level of crop productivity required, frequency and amount of water applied, and type of fertilizer applied and its release rate.

The type of crop influences timing and frequency of application since some crops are heavier feeders of particular nutrients than others. Root crops require less nitrogen fertilization than do leafy crops. Corn is a heavy feeder of nitrogen, and may require nitrogen fertilization every four weeks. A general rule of thumb is that nitrogen is for leafy top growth; phosphorus is for root and fruit production; and potassium is for cold hardiness, disease resistance, and general durability.

Proper use of nutrients can control plant growth rate and character. Nitrogen is the most critical nutrient in this regard. If tomatoes are fertilized too heavily with a nitrogen fertilizer or side-dressed before fruit set, the plants may be all vine and no fruit. This is also the case with potatoes, which will show excess vining and poor tuber formation.

If slow-release fertilizers or heavy amounts of manure are used on crops that form fruit or vegetables, leaf and vine growth will continue into late summer, and fruit and vegetable development will occur very late in the season.

Remember that a nitrogen application will have its greatest effect for three to four weeks after application. If tomatoes are fertilized heavily on June 1, there may be no flower production until July 1, which will, in turn, delay fruit ripening until late August. For this reason, it is important to plant crops with similar fertilizer needs close together to avoid improper rates of application.

Table 1 provides a list of elements and the deficiency symptoms.

Table 1 - Elements versus Deficiency Symptoms
Elements Deficiency Symptoms Comments

Major Elements

Nitrogen (N)

Stunted, yellowing from older to younger leaves and leaf tip back to petiole. Reduced size. Slow, stunted growth.

Heavy application may cause leaf burn; excess promotes flowering. Easily leached from soil.

Phosphorus (P)

Stunted, short internodes, purple or dark green foliage; old leaves die back; flowers and fruit poor. Slow growth, delayed maturity.

Phosphorus is poorly available at high and low pH, in dry or cold soils, and in high-organic container soils. Apply according to soil test.

Potassium (K)

Older leaves scorched on margin; weak stem; fruit shriveled, uneven ripening.

Fairly easily leached, primarily on sandy soil. Fertilize according to soil test.

Trace Element

Boron (B)

Tip of growing plant dies; bud becomes light green; roots are brown in center; fruit is corky; brown in center; flowers do not form.

Some Virginia soils are low in boron. Managed best by organic matter additions.

Calcium (Ca)

Young leaves turn yellow then brown; growing tip bends; weak stem; short dark roots. Causes blossom end rot of tomato.

Properly limed soils usually supply adequate calcium.

Copper (Cu)

Leaves appear bleached, elongated; new growth dies back.

 

Iron (Fe)

Young leaves are yellow between veins first, top to bottom; veins, margins, and tips stay green.

Usually due to pH problems. May use iron sulfate or chelated iron.

Magnesium (Mg)

Leaves are thin, lose color from between veins from bottom of plant up; tend to curve upward.

Use dolomitic lime according to soil test. May use epsom salt solution.

Manganese (Mn)

Tissue between veins turns white; leaves have dead spots; plant is dwarfed.

Seldom a problem, except on sandy Coastal Plain soils

Molybdenum (Mo)

Plant is very stunted, pale and distorted leaves.

Seldom a problem.

Sulphur (S)

Lower leaves yellow; stem and root in diameter; stems hard and brittle.

Seldom a problem.

Zinc (Zn)

Terminal leaves are small; bud formation is poor; leaves have dead areas.

Seldom a problem, except on high pH (>6-7) soils.

 

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