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Characteristics of Red Clover

Red clover (Trifolium pratense L.) is grown throughout the northeastern U.S. for forage production and use in rotations for soil improvement. It is adapted to areas where summer temperatures are moderate and adequate moisture is available throughout the growing season. Unlike alfalfa, red clover will grow moderately well on slightly acid soils. However, maximum yields are obtained when the pH is 6.0 or higher.

Red clover is a short-lived perennial, which usually produces two or three hay crops per year. It is characterized by rapid spring growth and low winterhardiness which contributes to its short-lived nature.

The growth habit of red clover varies from erect to prostrate. Numerous stems with large trifoliate leaves arise from the crown region each year. Red clover has a thick tap root which grows to a length of 24-36 inches. Lateral roots which arise from the tap root are mainly concentrated in the upper 5 inches of the soil. Small ovoid, pinkish, nitrogen fixing nodules can be found on the lateral roots if it is actively incorporating atmospheric nitrogen into protein nitrogen.

Adapted Varieties

Look for good disease resistance and persistence in a red clover variety. Varieties which are resistant to both Northern and Southern Anthracnose and Powdery Mildew are recommended for use throughout the states. There are several red clover varieties marketed in Pennsylvania that have been bred for better persistence. With proper management, you can expect these varieties to persist for two to three years after the establishment year. Refer to the current Penn State Forage Trial Report for red clover variety performance and resistance information.

Red Clover Establishment

Red clover can be established as a pure stand, with or without a companion crop, seeded with forage grass, or sod-seeded into a grass sod to improve the existing stand. Each situation has special requirements that should be considered.

Seeding red clover in the spring (April to early May) alone or with a spring oat companion crop in a conventionally prepared seed bed is common. Best clover stands result from seeding the oats at about 1.5 to 2 bushels per acre. Harvesting the oats early for silage is recommended because will greatly reduce the competition with the red clover. If the oats are harvested for grain, remove the straw so that it will not shade or suppress the red clover.

Red clover direct seeded in the spring without a companion crop, will yield less total forage than when seeded with a companion crop to be harvested as a forage. However, a larger portion of the forage will be red clover when seeded without the companion crop. Use of herbicides may be necessary when direct seeded red clover without a companion crop. Direct seedings of red clover can be made either by broadcast, band seeding or fluid seeding. The success of red clover establishment by the fluid seeding technique (planting in a carrier of water or fertilizer solution) is dependent on the preparation of firm and fine seed bed prior to seeding and cultipacking after seeding. Fluid seeding requires special equipment, therefore a custom applicator is recommended.

Red clover can be no-till seeded and is the easiest legume to establish using this method. Early spring seeding in winter grains or grass pastures when the soils are honeycombed from frost has also been successful.

Red clover should be seeded at a rate of 10 to 12 lb. per acre in pure stand and 6 to 8 lb. per acre when seeded with a forage grass. Best establishment occurs when red clover is not seeded deeper than 1/4 in.

To insure adequate nodulation, red clover seed should be inoculated just before seeding with Rhizobium trifolii bacteria and a sticking agent. Pre- inoculated seed should be kept in a cool, dark place to optimize survival of the nitrogen fixing bacteria.

Red Clover Harvest Management

Red clover quality is comparable to that of alfalfa under similar harvest schedules. However, intake by the consuming animal is generally greater for alfalfa than red clover. Red clover quality does not decline as rapidly with maturity as does alfalfa quality. This provides a longer time period over which high quality forage can be harvested.

Spring-seeded red clover can be harvested three times during the seeding year if growing conditions are favorable. This more aggressive harvest management in the seeding year than has traditionally been implemented provides greater forage and nutrient yields and has not negatively effected yield in the year after establishment. In addition, the third harvest during early September will help maintain better stands the following harvest season. Initial harvest 60-70 days after seeding and subsequent harvest on a 30-35 day interval will generally allow for three harvests during the seeding year.

Established red clover stands should be harvested at prebloom or early bloom. This harvest timing is a compromise between red clover yield and quality. Traditionally, 3 annual harvest are made in most of Pennsylvania. However, newer red clover varieties may tolerate 3 harvests during the summer and an additional fall harvest. The fall harvest should be made only if adequate herbage is present to offset the cost of harvesting. This harvest schedule will not allow red clover to reseed itself but will minimize the occurance of black patch disease and optimize yield and quality.

Red clover silage, if properly harvested and stored, provides a high quality forage. However, red clover is more difficult to cure for hay than other legumes. Establishing with a forage grass will decrease the curing time of red clover. The use of chemical drying agents and hay preservatives may make it possible to successfully make red clover hay under Pennsylvania's rainy conditions.

Red Clover Fertility

Soil tests are required for proper determination of soil nutrient availability. In soils with a pH below 6.0, addition of lime is essential to make the soil less acidic and improve the nitrogen fixing activity of red clover. Nutrients should be added to the soil on the basis of a soil test. Starter fertilizer applications up to 20-60-20 lb. per acre may benefit red clover seedings. Soil test recommendations which exceed this amount should be incorporated into the seedbed prior to planting.

Nitrogen (N) is essential for amino acid and protein production. Atmospheric N is captured (fixed) and converted into plant N by well nodulated plants. On acid soils with pH less than 5.5, nodulation and N fixation are suppressed and fertilizer N should be suppled for vigorous growth. However, excess N fertilizer also reduces nodulation and substitutes for atmospheric N which would have been fixed by the nodule.

Red clover should be top dressed annually with fertilizer (using soil testing as a guide for determining fertilizer requirements) as long as the plant numbers are sufficient for economic production. When the red clover makes up less than 30 percent of the clover-grass mix, apply 30 or 50 pounds of N per acre on sandy or clay soils, respectively.

Red Clover Summary

Red clover is a short-lived perennial which is adapted to wetter and lower pH soils than alfalfa. It is a vigorous establisher and good yielder in the establishment year. It is very well suited for use as the forage legume in short rotations with corn. However, difficulties drying the herbage enough under Pennsylvania weather to safely bale has been a deterrent to its wide spread use. Red clover use for silage production will circumvent that problem.

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This page was last updated on November 16, 2002