PRODUCTION OF PLANTING STOCK

FLOYD M. COSSITT, C. A. RINDT, HARRY A. GUNNING.

To produce the millions of treelings that are needed for reforestation and for planting on farm woodlands, wildlife areas, stream banks, windbreaks, and erosion-control projects in the United States, nurserymen grow more than 40 coniferous species of trees and shrubs and fifty-odd hardwood species. To get the quality, quantity, and variety needed, the growers have to observe most carefully, in exact sequence, a number of well-defined procedures. Their work embraces the attention to detail that the grower of orchids must have, the cycles of seed-time and harvest that govern the farmer's work, the long view of things that the parent takes in rearing children. Nurserymen must have practical knowledge of a half dozen sciences genetics, botany, entomology, soils, dendrology, pathology. Patience, too.

From the time they sow the seed in the nursery until the trees are ready to be shipped to the planting site, the men must care for the seedlings scientifically to make them strong enough to stand the hardships they will encounter in their permanent home. The nursery soil must contain certain plant nutrients in the right amounts necessary for healthy growth. The nursery stock must be protected from many diseases, weeds, as well as insects. Cold hardiness, shade requirement, tolerance to sun, and other factors must be observed. Too much water makes the trees soft and weak; too little retards their growth. Some species must remain in the nursery as long as 5 years, maybe more, before they are ready to be planted in the field; others are ready in a year. All can better live and populate a new forest if they have had proper care in the nursery.

Every State in the United States has some form of planting program that requires nursery stock. The Forest Service operates nurseries to produce planting stock for reforestation on national forests and for a few States that have cooperative programs with farmers. The Soil Conservation Service has nurseries to produce trees for farms in the organized soil conservation districts. Other federal agencies, among them the Fish and Wildlife Service, of the Department of the Interior, and the Tennessee Valley Authority, conduct planting programs on land they administer. The State nurseries, which provide planting stock for use on State-owned land and for use by farmers, are increasing in number and quantity of production. Many private lumber companies, paper-pulp companies, and soil conservation districts are establishing nurseries to get stock for their own forestry programs. Some private individuals, too, are finding pleasure and profit in operating small nurseries.

This discussion deals with large-scale nursery operations, but the man who wants to grow his own stock might find in it many helpful suggestions.

Nursery-grown trees were planted on 181,000 acres in the United States in 1947. Approximately 217 million trees were used. To date, in the United States, nearly 6,700,000 acres have been planted with more than 8 billion trees and shrubs that started life in nurseries.

SELECTING A GOOD SITE is of first importance in successful nursery management. Its topography, location, fertility, soil texture, drainage, and availability of water affect markedly the cost and quality of the stock. One rarely finds an area that has all the desirable features of an ideal nursery site; compromises usually are necessary, but the extent and number of the exceptions determine the desirability of the site.

The acreage required depends on the age and the species of trees to be grown. Approximately 1,000,000 conifer seedlings can be produced on an acre with seedbed densities of 30 plants to the square foot. Correspondingly greater acreage production can be had under densities of 90 to 100 plants to the square foot. Transplanted conifers in beds with 6-inch row spacing will approximate 400,000 plants an acre. Row-planted deciduous trees will produce 150,000 usable plants an acre.

In the Southern States, most of the species used for reforestation will attain field-planting size in a single growing season. In the Northern States, because of a shorter season and slower-growing species, from 2 to 5 years are needed to produce satisfactory field-planting stock. The acreage of nursery land required to meet an annual production quota, therefore, is a matter of arithmetic that takes into account species, season, and proper consideration of the fact that enough land must be provided to permit rotations of trees and soiling crops.

The ideal nursery site is most likely to be a smooth, flat, moderately sandy soil on a stream terrace. The site should have a uniform slope, preferably in one direction in order to facilitate surface drainage. Terraces are needed where the nursery is on an erosive soil with a slope in excess of 2 percent. In coniferous nurseries, Nichols-type terraces are considered best so that tractor-drawn cultivating equipment can cross them. Broadleaf trees usually are grown in drill rows spaced 16 to 42 inches apart. A hilly or irregular surface adds materially to the cost of operations; it is poor economy to begin production on anything but the best available site, even though the initial investment may seem high.

Serious consideration also should be given to the hazards of flooding; the lateness of spring frosts and the earliness of fall frosts; the season at which digging can be started and its relation-

ship to the planting area; accessibility to the nursery on all-weather roads; availability of public utilities electric power, telephone, telegraph, and railroads and other shipping facilities.

TEXTURE OF SOIL bears importantly on all cultural operations of a nursery. It must be friable to permit working in the fall and winter and earlier in the spring than one does with ordinary farm crops. Sandy loam soils are considered best. They should have a silt and clay content of 15 to 25 percent, and an alkalinity range of 5.5 to 6.5 pH. Extremely sandy soils are unsuitable because leaching removes plant nutrients at a rapid rate. On the other hand, heavy soils demand greater care in nearly all cultural operations and are subject to frost heaving in the colder climates.

If the topsoil is a fertile, porous, sandy loam that is underlaid with a retentive subsoil, it is ideal for producing nursery stock. A subsoil with a hardpan should be avoided because it prevents good drainage. Seedlings grow vigorously with well-developed roots in a deep soil of good quality; they develop a ramifying root system with few fibrous roots where the soil is poor.

THE SPECIES of the stock to be produced has some bearing on the selection of the nursery site, but it is not of first importance. It is wise, however, to locate the nursery within the planting region. Many nurseries produce both conifer species and deciduous species. The deciduous species generally are tolerant of a wider variety of soil conditions. Conifers do best in soils with an alkalinity range of from 5.0 to 6.0 pH. Soils with a higher alkalinity are more favorable to fungi, which cause mortality in young coniferous seedlings.

Seasonal laborers are required in nursery work, particularly for 2 or 3 months in the spring and early summer and in the fall. The nursery should be located where labor is available and where the minimum amount of time is required to go to and from work.

The first step in developing a nursery site is to bring the soil into good physical condition. Then suitable facilities buildings for storage and equipment must be built to meet the needs of the program. A soil conservation plan is needed so as to retain and improve fertility and prevent erosion. Terraces and drainage should be put in where necessary. It is wise to make several maps and keep them up to date: A topographic and soil map of the nursery; a plan that shows all permanent features; and a map, to be prepared each year, that shows the current use of each unit or part of a unit, including treatment of the soil, species of nursery stock on it, and age class. The maps serve as a record of stock produced and are a year-to-year record of soil management. Permanent roads that divide the plots into workable units should be established.

BUILDINGS vary in number, kind, and character with the climate and location of the nursery in relation to labor and other services.

In some climates, trees can be graded and packed for shipment as they are dug.

Where the digging season is short or the weather is unfavorable, stock must be graded and packed under shelter. In some climates, where the planting seasons do not coincide with the nursery seasons, cold storage is needed to hold nursery stock when it is out of the ground, and a well-designed building that has facilities for sorting, packing, and storage of nursery stock is essential. In mild climates, a simple shelter and a temporary heeling-in bed usually are enough.

The superintendent, or nursery foreman, should reside on the grounds so as to be always within reach. On a large nursery, houses may be desirable for other yearlong personnel. The operations of a nursery demand 24-hour attention; neglect at critical periods may mean loss of trees. Sometimes a dormitory and mess hall are necessary for laborers. Besides the quarters for personnel, buildings are needed for office, laboratory, storage of equipment, seed extracting and cleaning, and for repair work. The repair shop should be designed to handle all but major re-pairs to equipment. Usually the office and laboratory can be in one building, which should be placed so that visitors will go there first for a proper welcome and an introduction to the work that is being carried on in the nursery.

IRRIGATION is necessary to the production of good plants in most nurseries, although some species can be grown without irrigation in regions where precipitation is adequate for farm crops.

Ordinarily, an overhead sprinkler system is used for the irrigation of conifers. Usually this consists of runs of 1 to 1 1/2-inch pipe up to 500 feet in length and 50 feet apart, with spray nozzles at 3-foot intervals, and supported on posts 2 to 6 feet above the ground. Water coverage on both sides of each pipe is obtained as the pipe is rotated from side to side by a water motor or oscillator. Other systems employ revolving sprinkler heads on upright pipes at intervals of 40 to 60 feet. The installations may be fed by permanent underground or portable surface pipes.

The quantity of water and the methods of applying it (especially to coniferous seedlings) strongly influence the quality of the stock. During the germination period, the seedbed must be kept moist but not saturated. An even distribution of water during the growing season results in a uniform growth of plants throughout the seedbed. The quantity of water needed varies with the soil, climate, and age class of the stock being grown. Under similar climatic conditions, a light, sandy soil demands more water than a heavier soil. First-year seedlings require more frequent light waterings than older stock.

LAND cannot be cropped repeatedly without measures to maintain its productivity. Nursery stock returns nothing to the soil because the trees are removed, root and branch. Nutrients are taken from the soil faster than they become available naturally. Nursery stock can be grown satisfactorily for several years on exceptionally good land, but the application of fertilizers becomes necessary sooner or later.