The Production of Grass Seeds

GEORGE A. ROGLER, HENRY H. RAMPTON, AND M. D. ATKINS.

THE GROWERS of seed aim to grow good seed of species and varieties that are in demand and to achieve economical production.

They know that it is easier to grow clean seed than to clean it up after harvest, and that once the seed reaches maturity they can do little more to improve its innate quality.

The best seed-rowers, are specialists. Seed production is their main farm enterprise. They have made many technological advances in the art of growing seeds.

Research workers, in studies of effects of environment and cultural practices on the life history of the grass plant, are changing this art into a science.

Some sections have become outstanding in the production of seeds because of conditions that favor low cost of production or a superior quality of seed or both.

Among the conditions are choice of crops; suitable soils; favorable growing seasons; ample supply of water; absence of objectionable weeds; warm, dry seasons for curing and harvesting seed; and the use of correct cultural and management practices.

Some seed is harvested from native grasslands, primarily in the Great Plains. The practice developed from the demand for seeds of the native grasses for converting croplands to grass and improving rangelands. Such seed harvests are sporadic. They occur only when seasonable moisture conditions are unusually favorable, but it is not uncommon to obtain several million pounds of seed annually in this way. No attempt is made to encourage development of seed by cultural or management practices.

Another source is the pastures of tame grass of the subhumid and humid areas of the Midwest, South, and East. They sometimes are fertilized and managed for seed production, but their primary use usually is for pasture or hay. A seed crop is taken when the seed appears to be more valuable than the forage.

A third source, the most dependable and the one we discuss in this chapter, is the grass crops grown primarily for seed.

TWO BROAD GROUPS of grasses are based on their season of growth.

Cool-season grasses grow actively at cool temperatures, develop rapidly in the spring, are more or less dormant during periods of high temperature and drought in summer, and recover active growth in the fall.

Most of the perennials among them have good winter hardiness. They flourish in the northern half of the United States.

They include the fescues, wheat-grasses, bluegrasses, bromegrasses, orchardgrass, timothy, ryegrasses, bent-grasses, and redtop.

The seedgrowers of the Pacific Northwest and Intermountain regions give special attention to perennial and common ryegrass; red, chewings, and tall fescues; bentgrass; Kentucky bluegrass; orchardgrass; and several wheat-grasses.

The wheatgrasses, smooth brome, and Russian wildrye are grown in the northern Great Plains.

Warm-season grasses make their maximum growth during the summer. They start spring growth about 3 weeks after cool-season grasses and cease growth with the first hard frost in the fall. They are predominant in the southern sections, where the long growing seasons have high temperatures and precipitation in summer.

Much seed is produced in the High Plains of western and southern Texas, and in western Oklahoma, Kansas, and Nebraska.

Some of the grasses in commercial production are buffelgrass, blue panicum, King Ranch bluestem, Caucasian bluestem, big sandbur, Arizona cottontop, plains bristlegrass, green sprangletop, sideoats grama, blue grama, little bluestem, sand bluestem, big bluestem, switchgrass, indiangrass, sand lovegrass, and bermudagrass.

THE ADAPTATION of a crop to its environment is reflected in its development and its yield of seed.

Warm-season grasses, for example, are not grown successfully in the Pacific Northwest, where the climate favors the cool-season grasses. Species and variety adaptation often is less limiting to the grower of grass seed than to the forage producer, however, because his crop is grass seed, which may be used elsewhere.

When seed is produced under special culture and management, environment often is less restrictive. Seed therefore may be produced in one area for use in another.

Quality is a watchword of the farmer who specializes in growing grass seed. The factors that mean quality in the seed he plants and the product he sells usually rank so: Genetic or varietal purity (Is it true to type?); mechanical purity (Is it free from inseparable seeds of other crops and weeds that cannot be economically controlled in the field and from undue quantities of inert matter?) ; germination (Will the seed produce vigorous healthy seedlings?).

To attain those standards, the grower must plant seed stock of high quality. He must select land that is sufficiently isolated to minimize cross-pollination from other fields and is free from weeds and other crops that are highly competitive or have seeds that are inseparable from the sown crop.

Grasses vary in adaptability to different soil conditions, but all respond in seed yields to the soil factors that favor the complete development of plants.

The most important conditions are adequate depth of soil to permit abundant development of roots; favorable drainage and supply of moisture; aeration, nutrient-supplying ability, and tilth of soil; and topography.

THE SEEDBED should have the proper moisture, temperature, tilth, and fertility to stimulate germination, rapid emergence of seedlings, and quick establishment of the stand.

Methods of preparing the seedbed for sowing grass seeds vary with soil type, climate, time of sowing, kind of grass, and the grower.

A plowed, well-tilled, and firm seedbed usually is prepared just before the planting.

If fertilizer or soil amendments are used, they may be mixed into the soil or applied in bands with the seeding.

Seed fields often are established in the Great Plains in the standing stubble of the previous crop. The stubble helps to control blowing soil, catches snow, reduces evaporation, and provides a firm surface.

MAXIMUM SEED production of most grasses can best be attained with wide-spaced rows-24 inches or more apart. Exceptions are stoloniferous species, such as buffalograss and bermudagrass, and low-growing bunchgrasses, such as blue grama and perennial ryegrass.

Wide-spaced rows result in cleaner seed, higher yields, better control of weeds, more economical use of fertilizer, and longer productive life of stands. They also permit a lower seeding rate and the stretching of limited or high-priced stock seeds of new varieties.

Row culture affords better utilization of limited moisture. Under irrigation, row planting facilitates furrowing and gravity irrigation.

Most row spacings are 24 to 48 inches apart, depending on the seeding, cultural, and harvesting equipment available; type of grass; and the grower's preference.

Row spacings up to 84 inches have been used successfully for Russian wildrye in the northern Great Plains.

Perennial grasses usually yield more seed when sown at rates lower than the optimum for forage production. The most effective seeding rates vary, naturally, with size of the seed. The amount for cultivated rows is one-half pound to 4 pounds an acre, and 2 to 16 pounds for close drills (6 or 7 inches).

Rhizomatous, sod-forming perennial grasses, such as smooth brome and intermediate wheatgrass, present special problems in the control of the plant population because they are vigorous spreaders. This habit results in dense growth, which is known as sod binding, and a rapid decline in yields of seeds.

Sod binding often can be delayed and seed production of some sod-bound grass often can be restored by providing adequate nitrogen, postharvest burning, and reducing the plant population by mechanical renovation.

Annual grasses, such as common rye-grass and sudangrass, usually respond in yields to heavier sowing rates, or about the same as for forage production. When the soil moisture is limited, the seed fields of sudangrass often are sown at lower rates in rows.

A DRILL should be used for planting. It has several advantages. The rate of sowing can be controlled more accurately. The seed is distributed more evenly. Seed can be covered at a uniform depth. Seedings can be made in wide-spaced rows. Fertilizer attachments can be used to place the fertilizer in bands beside or below the seed.

The fluted feed grain drill, modified to sow at the desired intervals, is popular. Drills for beets or beans, corn planters, and shop-built seeders frequently are used for sowing rows and are superior to a grain drill.

Many seedgrowers in the southern Great Plains use a specially built, two-row, tractor-mounted planter.

It is equipped with cotton boxes (for light, trashy, or awned seed) and vegetable boxes (for small, free-flowing seed). It has double-disk furrow openers, with depth-control bands, and heavy press wheels. All are important features of a planter unit.

Chaffy, fluffy, or heavily awned seeds are sometimes mixed with free-flowing material of a similar weight, such as rice hulls, to aid in getting the seed through a drill.

SOWING too deep causes many failures to get stands of grass. Seeding equipment therefore should have accurate devices to control depth.

Desirable sowing depths vary with the type of soil, kind of seed, depth, moisture, and the season of seeding.

For quick emergence of seedlings the seed must be placed in moist soil but that does not mean seeding so deep that the seedlings cannot emerge.

In general, bentgrass and Kentucky bluegrass should be seeded no deeper than one-fourth inch; the fine fescues timothy, and most warm-season grasses no deeper than one-half inch; and smooth brome, wheatgrasses, ryegrass tall fescue, meadow fescue, orchard grass, and tall oatgrass, no deeper than 1 inch.