Page:Growing Black Locust Trees.djvu/11

Rh coats and the consequently varying degree to which moisture, necessary for germination, passes through them.

Different treatments to increase germination have been worked out and tried, with varying results. (1) The one longest in use is the hot-water treatment. It consists of soaking the seed in warm water, starting at somewhat below the boiling point (about 160° F.), for 12 to 20 hours. (2) The chemical method is to treat the seed with sulphuric acid. (3) The mechanical treatment is to scarify, scratch, wear, or thin down the seed coats. Various means include agitating the seed in a revolving drum or other container in which it is mixed with sand or small gravel; shaking it in a sealed jar; tumbling it in some sort of a revolving hopper or drum in which baffle plates are fitted; or blowing it against a curved surface covered with a sharp sandpaper or garnet paper. This last method has given good results as it finely scratches the seed coats without cracking them and bringing about consequent loss of seed. There are various scarifying machines on the market designed for treating clover and other agricultural seed which, with simple modifications, can be successfully used for black locust seed.

The hot-water treatment is easy to apply and is known to hasten germination in many lots of seed, but in many others is ineffective because of the very hard and impermeable seed coats. The acid treatment requires much care in handling, including length of treatment. When rightly applied, it markedly aids germination, but at the same time causes losses of young seedlings under warm, wet soil conditions. The best combined results of germination and of hardiness of the resulting young seedlings have apparently been obtained when the seed was scarified. Much probably will be learned by means of further experiments. It might be advisable to treat a portion of the seed by one or more of the methods and observe the results as compared with sowing the seed without any special treatment.

Directions for treating black locust seed, if desired, will be furnished upon request if application is made to the regional forester, United States Forest Service, at Washington, D. C., at Atlanta, Ga., or at Milwaukee, Wis.

A good quality of agricultural soil, such as a deep sandy loam, should be chosen for the nursery site. Apparently a slightly acid soil gives the most favorable development of locust seedlings and at the same time freedom from disease (soils with a pH of about 5.00+).

It is essential to prepare the soil thoroughly in readiness for seed sowing and to mark out beds 4½ feet in width, with paths 18 or 24 inches in width. A farmer may not need more than a single bed. Generally, a bed 4½ feet in width by 25 feet in length (100 square feet of seeded bed) sown in drills 6 inches apart will require about one-third pound of seed and may be expected to produce from 800 to 1,500 or an average of 1,200 good or no. 1 locust seedlings.

Early spring is a favorable time for seed sowing in order to take advantage of the better soil moisture—an important requirement for good germination. One method is to sow seed in drills 4 feet