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Six good reasons to coat forage seed

INTRODUCTION

Prill-On®, Rhizoseal® and Nutriprill® coated seed, while no longer new, are still considered a recent development in seed technology, especially in Canada. Coated Seed was pioneered in New Zealand in the mid-fifties and the concept was introduced into the United States in the sixties.

There are six good reasons why we coat forage and turf seeds. These are:

1) Pre-inoculation of legumes

2) Nutrient benefits

3) Safe, effective application of agricultural chemicals e.g. Apron

4) Protection from stress conditions

5) Protection from rodents, birds and the harmful effects of some fertilizers

6) To improve ballistic properties and facilitate seeding

1) PRE-INOCULATION:

Pre-inoculation is the addition of nodule bacteria (rhizobia) to the seed, weeks or even months in advance of sowing. It ensures that the bacteria are in close proximity to the roots of the germinating seedling and thus, in a position to cause fast, effective nodulation.

The need for legume inoculation is now widely recognized, particularly in the case of trefoils, as there are few native populations of the rhizobium necessary to induce nodulation in this species present in Canadian soils.

It is true that areas of Canada do have populations of rhizobium meliloti (alfalfa bacteria) and that in many cases, uninoculated alfalfa seed would nodulate when sown in these soils. It is also true that the yield of many of the plants infected by these native bacteria would be significantly greater had they been nodulated by the more effective strains of rhizobium used in the Prill-On®, Rhizoseal® and Precision-Cote® processes.

Millions of dollars are spent by Agriculture Canada Research Scientists each year in an attempt to develop new strains of rhizobia which can utilize the rhizobium-legume association far more effectively than native rhizobium strains. The need for nodulation is obvious. Effectively nodulated legumes can fix large amounts of nitrogen from the atmosphere. Pure alfalfa stands in Ontario are capable of fixing approximately 150 kilograms of nitrogen per hectare per year.

All pre-inoculated seeds are monitored by Agriculture Canada to ensure that at least 1,000 viable rhizobia are present on the seed at the time of its sale to the farmer. Our Prill-On® and Rhizoseal® products often contain in excess of 100,000 viable rhizobium per seed.

2) NUTRIENT BENEFITS:

Seed coating creates a nutritious environment around the establishing seedling and increases vigor during its critical early development. The main nutrient included in our seed coatings is phosphorus. Twenty percent of all Precision-Cote® and Nutriprill® grass seed coating and nine percent of Prill-On® and Precision-Cote® legume coating is phosphatic fertilizer, which is essential for root development and seedling establishment. Even on soils with sufficiently high phosphorus levels to sustain normal growth, localized placement is very beneficial. It is desirable from the standpoint of accessibility to the establishing seedling and in order to reduce fixation. Phosphorus does not move in the soil, therefore, the nearer it can be placed to the seed, the easier it can be utilized by the seedling.

3) AGRICULTURAL CHEMICALS:

In 1979, the Federal Government introduced regulations requiring all alfalfa seed sown in Canada to be treated with Thiram. Although Thiram is no longer required on alfalfa seed, other chemicals are still used. e.g. Apron. Research data available from trials using Apron indicate that it may have a detrimental affect on the viability of some strains of rhizobium. Research with coated seed products containing Apron has shown good compatibility between Apron and rhizobium when the rhizobium are encased by the layering effect of the coating materials.

Alfalfa treated with Thiram or Apron also raises the question of chemical toxicity. The Prill-On®, Rhizoseal® and Precision-Cote® processes can treat alfalfa seed if required by applying these chemicals directly to the seed and then surrounding them with our normal coating materials. Obviously, this is the safest method of applying any toxic substance to seed and will minimize the chances of the end user coming into contact with the toxic chemical. In addition to Apron, virtually any chemical that is required can be incorporated into the Prill-On®, Rhizoseal® or Precision-Cote® coating processes.

4) PROTECTION FROM STRESS CONDITIONS:

The coating materials, as well as the physical barrier created by the coat itself, protect the rhizobia and seed from low pH conditions. Calcium Carbonate is very effective in buffering soil pH in the micro-environment around the seed. The pH range of coated seed (6.5 to 7) is the optimum pH range for nutrient uptake and while desiccation can quickly reduce the rhizobium populations, the coat offers the bacteria protection from the effects of drying winds and sun.

Prill-On trefoil seeded under severe drought conditions. Wet or dry, Prill-On trefoil comes through.

This is especially beneficial when forage legumes are sown by air or broadcast.

5) PROTECTION FROM ANIMALS, BIRDS AND FERTILIZERS:

Most rodents and birds do not recognize coated seed as food. The increased size of the seed is one-reason birds do not take it and the coating materials, especially the dyes and phosphate used in turfgrasses, are not at all palatable to either rodents or birds. Some fertilizers, e.g. superphosphate and sulphate of ammonia, can’t be mixed with uncoated seed. The coating layer protects both the seed and the rhizobia from the harmful effects of these fertilizers.

6. BALLISTIC PROPERTIES:

Coated grass seed is approximately twice the weight of bare seed. Aerial sown grasses penetrate ground cover easier than bare seed and thus make better contact with the seedbed. Some seeds, e.g. meadow foxtail and bromegrass, are difficult to sow due to their very light weight. Coating can increase the weight of these species, by as much as three times and this, combined with the increased size of the seed, facilitates sowing.

These six good reasons for coating all combine to offer the farmer superior establishment at little or no extra price.

Coated seed, in particular Prill-On®, Rhizoseal® and Precision-Cote®, has been well received by the North American farmer. However, in the early days as with any new product, there will always be some criticism. The biggest criticism was that the farmer did not received enough seed for his money. However, the following points are often overlooked when this subject is discussed.

a) Prill-On® and Precision-Cote® coated legume seeds contain 67% seed and 33% coating material, while Rhizoseal® contains 90% seed.

b) The coating around the seed is made up of the following components each of which has its own specific purpose:
.

1) Rhizobium (nitrogen fixing organisms)

2) Peat and sugars to help maintain the viability of the rhizobium

3) Adhesives - to bind the coating materials to the seed

4) Agricultural chemicals to protect the seed from pests and diseases.

5) Available phosphoric acid

6) Finely ground Calcium Carbonate or Talc.

c) Prill-On®, Rhizoseal® and Precision-Cote® are pre-inoculated. This benefits the farmer by saving him the messy and time consuming job of inoculating the seed as this has already been done, using the most effective strains of rhizobium available.

d) Trials with coated seed using a product containing only 67% seed have shown that a seeding rate of 10 to 12 pounds per acre of either bare or coated seed will result in an equal yield of alfalfa.

In effect, coated seed offers the farmer at least an equal yield for less time and often less money.

Some people expect coated seed to provide large yield increases and allow them to ignore good seeding techniques at planting time. Coated seed does provide major advantages however, good cultivation and planting techniques must still be followed. Obviously, coating cannot alter the inherent genetic characteristics of the seed such as yielding capacity.

Research is continuing in an attempt to provide further benefits to the user. We now have a product which is physically stable and contains high numbers of viable rhizobia. Today’s coated seeds benefit the plant only in its critical seedling stage, ensuring early vigor and in the case of legumes, fast effective nodulation. There is obviously some carryover affect from this increased seedling vigor but once the plant has nodulated and the fertilizer in the coat has been used up, the coating cannot directly benefit the plant in its future development.

The nutritional and cost savings advantages make coated seed a very worthwhile proposition. In addition, seed coating is now recognized as the most effective method of pre-inoculation for legumes and this will ensure an even greater acceptance in the future.